Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : * applyparallelworker.c
3 : : * Support routines for applying xact by parallel apply worker
4 : : *
5 : : * Copyright (c) 2023-2024, PostgreSQL Global Development Group
6 : : *
7 : : * IDENTIFICATION
8 : : * src/backend/replication/logical/applyparallelworker.c
9 : : *
10 : : * This file contains the code to launch, set up, and teardown a parallel apply
11 : : * worker which receives the changes from the leader worker and invokes routines
12 : : * to apply those on the subscriber database. Additionally, this file contains
13 : : * routines that are intended to support setting up, using, and tearing down a
14 : : * ParallelApplyWorkerInfo which is required so the leader worker and parallel
15 : : * apply workers can communicate with each other.
16 : : *
17 : : * The parallel apply workers are assigned (if available) as soon as xact's
18 : : * first stream is received for subscriptions that have set their 'streaming'
19 : : * option as parallel. The leader apply worker will send changes to this new
20 : : * worker via shared memory. We keep this worker assigned till the transaction
21 : : * commit is received and also wait for the worker to finish at commit. This
22 : : * preserves commit ordering and avoid file I/O in most cases, although we
23 : : * still need to spill to a file if there is no worker available. See comments
24 : : * atop logical/worker to know more about streamed xacts whose changes are
25 : : * spilled to disk. It is important to maintain commit order to avoid failures
26 : : * due to: (a) transaction dependencies - say if we insert a row in the first
27 : : * transaction and update it in the second transaction on publisher then
28 : : * allowing the subscriber to apply both in parallel can lead to failure in the
29 : : * update; (b) deadlocks - allowing transactions that update the same set of
30 : : * rows/tables in the opposite order to be applied in parallel can lead to
31 : : * deadlocks.
32 : : *
33 : : * A worker pool is used to avoid restarting workers for each streaming
34 : : * transaction. We maintain each worker's information (ParallelApplyWorkerInfo)
35 : : * in the ParallelApplyWorkerPool. After successfully launching a new worker,
36 : : * its information is added to the ParallelApplyWorkerPool. Once the worker
37 : : * finishes applying the transaction, it is marked as available for re-use.
38 : : * Now, before starting a new worker to apply the streaming transaction, we
39 : : * check the list for any available worker. Note that we retain a maximum of
40 : : * half the max_parallel_apply_workers_per_subscription workers in the pool and
41 : : * after that, we simply exit the worker after applying the transaction.
42 : : *
43 : : * XXX This worker pool threshold is arbitrary and we can provide a GUC
44 : : * variable for this in the future if required.
45 : : *
46 : : * The leader apply worker will create a separate dynamic shared memory segment
47 : : * when each parallel apply worker starts. The reason for this design is that
48 : : * we cannot predict how many workers will be needed. It may be possible to
49 : : * allocate enough shared memory in one segment based on the maximum number of
50 : : * parallel apply workers (max_parallel_apply_workers_per_subscription), but
51 : : * this would waste memory if no process is actually started.
52 : : *
53 : : * The dynamic shared memory segment contains: (a) a shm_mq that is used to
54 : : * send changes in the transaction from leader apply worker to parallel apply
55 : : * worker; (b) another shm_mq that is used to send errors (and other messages
56 : : * reported via elog/ereport) from the parallel apply worker to leader apply
57 : : * worker; (c) necessary information to be shared among parallel apply workers
58 : : * and the leader apply worker (i.e. members of ParallelApplyWorkerShared).
59 : : *
60 : : * Locking Considerations
61 : : * ----------------------
62 : : * We have a risk of deadlock due to concurrently applying the transactions in
63 : : * parallel mode that were independent on the publisher side but became
64 : : * dependent on the subscriber side due to the different database structures
65 : : * (like schema of subscription tables, constraints, etc.) on each side. This
66 : : * can happen even without parallel mode when there are concurrent operations
67 : : * on the subscriber. In order to detect the deadlocks among leader (LA) and
68 : : * parallel apply (PA) workers, we used lmgr locks when the PA waits for the
69 : : * next stream (set of changes) and LA waits for PA to finish the transaction.
70 : : * An alternative approach could be to not allow parallelism when the schema of
71 : : * tables is different between the publisher and subscriber but that would be
72 : : * too restrictive and would require the publisher to send much more
73 : : * information than it is currently sending.
74 : : *
75 : : * Consider a case where the subscribed table does not have a unique key on the
76 : : * publisher and has a unique key on the subscriber. The deadlock can happen in
77 : : * the following ways:
78 : : *
79 : : * 1) Deadlock between the leader apply worker and a parallel apply worker
80 : : *
81 : : * Consider that the parallel apply worker (PA) is executing TX-1 and the
82 : : * leader apply worker (LA) is executing TX-2 concurrently on the subscriber.
83 : : * Now, LA is waiting for PA because of the unique key constraint of the
84 : : * subscribed table while PA is waiting for LA to send the next stream of
85 : : * changes or transaction finish command message.
86 : : *
87 : : * In order for lmgr to detect this, we have LA acquire a session lock on the
88 : : * remote transaction (by pa_lock_stream()) and have PA wait on the lock before
89 : : * trying to receive the next stream of changes. Specifically, LA will acquire
90 : : * the lock in AccessExclusive mode before sending the STREAM_STOP and will
91 : : * release it if already acquired after sending the STREAM_START, STREAM_ABORT
92 : : * (for toplevel transaction), STREAM_PREPARE, and STREAM_COMMIT. The PA will
93 : : * acquire the lock in AccessShare mode after processing STREAM_STOP and
94 : : * STREAM_ABORT (for subtransaction) and then release the lock immediately
95 : : * after acquiring it.
96 : : *
97 : : * The lock graph for the above example will look as follows:
98 : : * LA (waiting to acquire the lock on the unique index) -> PA (waiting to
99 : : * acquire the stream lock) -> LA
100 : : *
101 : : * This way, when PA is waiting for LA for the next stream of changes, we can
102 : : * have a wait-edge from PA to LA in lmgr, which will make us detect the
103 : : * deadlock between LA and PA.
104 : : *
105 : : * 2) Deadlock between the leader apply worker and parallel apply workers
106 : : *
107 : : * This scenario is similar to the first case but TX-1 and TX-2 are executed by
108 : : * two parallel apply workers (PA-1 and PA-2 respectively). In this scenario,
109 : : * PA-2 is waiting for PA-1 to complete its transaction while PA-1 is waiting
110 : : * for subsequent input from LA. Also, LA is waiting for PA-2 to complete its
111 : : * transaction in order to preserve the commit order. There is a deadlock among
112 : : * the three processes.
113 : : *
114 : : * In order for lmgr to detect this, we have PA acquire a session lock (this is
115 : : * a different lock than referred in the previous case, see
116 : : * pa_lock_transaction()) on the transaction being applied and have LA wait on
117 : : * the lock before proceeding in the transaction finish commands. Specifically,
118 : : * PA will acquire this lock in AccessExclusive mode before executing the first
119 : : * message of the transaction and release it at the xact end. LA will acquire
120 : : * this lock in AccessShare mode at transaction finish commands and release it
121 : : * immediately.
122 : : *
123 : : * The lock graph for the above example will look as follows:
124 : : * LA (waiting to acquire the transaction lock) -> PA-2 (waiting to acquire the
125 : : * lock due to unique index constraint) -> PA-1 (waiting to acquire the stream
126 : : * lock) -> LA
127 : : *
128 : : * This way when LA is waiting to finish the transaction end command to preserve
129 : : * the commit order, we will be able to detect deadlock, if any.
130 : : *
131 : : * One might think we can use XactLockTableWait(), but XactLockTableWait()
132 : : * considers PREPARED TRANSACTION as still in progress which means the lock
133 : : * won't be released even after the parallel apply worker has prepared the
134 : : * transaction.
135 : : *
136 : : * 3) Deadlock when the shm_mq buffer is full
137 : : *
138 : : * In the previous scenario (ie. PA-1 and PA-2 are executing transactions
139 : : * concurrently), if the shm_mq buffer between LA and PA-2 is full, LA has to
140 : : * wait to send messages, and this wait doesn't appear in lmgr.
141 : : *
142 : : * To avoid this wait, we use a non-blocking write and wait with a timeout. If
143 : : * the timeout is exceeded, the LA will serialize all the pending messages to
144 : : * a file and indicate PA-2 that it needs to read that file for the remaining
145 : : * messages. Then LA will start waiting for commit as in the previous case
146 : : * which will detect deadlock if any. See pa_send_data() and
147 : : * enum TransApplyAction.
148 : : *
149 : : * Lock types
150 : : * ----------
151 : : * Both the stream lock and the transaction lock mentioned above are
152 : : * session-level locks because both locks could be acquired outside the
153 : : * transaction, and the stream lock in the leader needs to persist across
154 : : * transaction boundaries i.e. until the end of the streaming transaction.
155 : : *-------------------------------------------------------------------------
156 : : */
157 : :
158 : : #include "postgres.h"
159 : :
160 : : #include "libpq/pqformat.h"
161 : : #include "libpq/pqmq.h"
162 : : #include "pgstat.h"
163 : : #include "postmaster/interrupt.h"
164 : : #include "replication/logicallauncher.h"
165 : : #include "replication/logicalworker.h"
166 : : #include "replication/origin.h"
167 : : #include "replication/worker_internal.h"
168 : : #include "storage/ipc.h"
169 : : #include "storage/lmgr.h"
170 : : #include "tcop/tcopprot.h"
171 : : #include "utils/inval.h"
172 : : #include "utils/memutils.h"
173 : : #include "utils/syscache.h"
174 : :
175 : : #define PG_LOGICAL_APPLY_SHM_MAGIC 0x787ca067
176 : :
177 : : /*
178 : : * DSM keys for parallel apply worker. Unlike other parallel execution code,
179 : : * since we don't need to worry about DSM keys conflicting with plan_node_id we
180 : : * can use small integers.
181 : : */
182 : : #define PARALLEL_APPLY_KEY_SHARED 1
183 : : #define PARALLEL_APPLY_KEY_MQ 2
184 : : #define PARALLEL_APPLY_KEY_ERROR_QUEUE 3
185 : :
186 : : /* Queue size of DSM, 16 MB for now. */
187 : : #define DSM_QUEUE_SIZE (16 * 1024 * 1024)
188 : :
189 : : /*
190 : : * Error queue size of DSM. It is desirable to make it large enough that a
191 : : * typical ErrorResponse can be sent without blocking. That way, a worker that
192 : : * errors out can write the whole message into the queue and terminate without
193 : : * waiting for the user backend.
194 : : */
195 : : #define DSM_ERROR_QUEUE_SIZE (16 * 1024)
196 : :
197 : : /*
198 : : * There are three fields in each message received by the parallel apply
199 : : * worker: start_lsn, end_lsn and send_time. Because we have updated these
200 : : * statistics in the leader apply worker, we can ignore these fields in the
201 : : * parallel apply worker (see function LogicalRepApplyLoop).
202 : : */
203 : : #define SIZE_STATS_MESSAGE (2 * sizeof(XLogRecPtr) + sizeof(TimestampTz))
204 : :
205 : : /*
206 : : * The type of session-level lock on a transaction being applied on a logical
207 : : * replication subscriber.
208 : : */
209 : : #define PARALLEL_APPLY_LOCK_STREAM 0
210 : : #define PARALLEL_APPLY_LOCK_XACT 1
211 : :
212 : : /*
213 : : * Hash table entry to map xid to the parallel apply worker state.
214 : : */
215 : : typedef struct ParallelApplyWorkerEntry
216 : : {
217 : : TransactionId xid; /* Hash key -- must be first */
218 : : ParallelApplyWorkerInfo *winfo;
219 : : } ParallelApplyWorkerEntry;
220 : :
221 : : /*
222 : : * A hash table used to cache the state of streaming transactions being applied
223 : : * by the parallel apply workers.
224 : : */
225 : : static HTAB *ParallelApplyTxnHash = NULL;
226 : :
227 : : /*
228 : : * A list (pool) of active parallel apply workers. The information for
229 : : * the new worker is added to the list after successfully launching it. The
230 : : * list entry is removed if there are already enough workers in the worker
231 : : * pool at the end of the transaction. For more information about the worker
232 : : * pool, see comments atop this file.
233 : : */
234 : : static List *ParallelApplyWorkerPool = NIL;
235 : :
236 : : /*
237 : : * Information shared between leader apply worker and parallel apply worker.
238 : : */
239 : : ParallelApplyWorkerShared *MyParallelShared = NULL;
240 : :
241 : : /*
242 : : * Is there a message sent by a parallel apply worker that the leader apply
243 : : * worker needs to receive?
244 : : */
245 : : volatile sig_atomic_t ParallelApplyMessagePending = false;
246 : :
247 : : /*
248 : : * Cache the parallel apply worker information required for applying the
249 : : * current streaming transaction. It is used to save the cost of searching the
250 : : * hash table when applying the changes between STREAM_START and STREAM_STOP.
251 : : */
252 : : static ParallelApplyWorkerInfo *stream_apply_worker = NULL;
253 : :
254 : : /* A list to maintain subtransactions, if any. */
255 : : static List *subxactlist = NIL;
256 : :
257 : : static void pa_free_worker_info(ParallelApplyWorkerInfo *winfo);
258 : : static ParallelTransState pa_get_xact_state(ParallelApplyWorkerShared *wshared);
259 : : static PartialFileSetState pa_get_fileset_state(void);
260 : :
261 : : /*
262 : : * Returns true if it is OK to start a parallel apply worker, false otherwise.
263 : : */
264 : : static bool
461 akapila@postgresql.o 265 :CBC 95 : pa_can_start(void)
266 : : {
267 : : /* Only leader apply workers can start parallel apply workers. */
268 [ + + ]: 95 : if (!am_leader_apply_worker())
269 : 31 : return false;
270 : :
271 : : /*
272 : : * It is good to check for any change in the subscription parameter to
273 : : * avoid the case where for a very long time the change doesn't get
274 : : * reflected. This can happen when there is a constant flow of streaming
275 : : * transactions that are handled by parallel apply workers.
276 : : *
277 : : * It is better to do it before the below checks so that the latest values
278 : : * of subscription can be used for the checks.
279 : : */
280 : 64 : maybe_reread_subscription();
281 : :
282 : : /*
283 : : * Don't start a new parallel apply worker if the subscription is not
284 : : * using parallel streaming mode, or if the publisher does not support
285 : : * parallel apply.
286 : : */
287 [ + + ]: 64 : if (!MyLogicalRepWorker->parallel_apply)
288 : 33 : return false;
289 : :
290 : : /*
291 : : * Don't start a new parallel worker if user has set skiplsn as it's
292 : : * possible that they want to skip the streaming transaction. For
293 : : * streaming transactions, we need to serialize the transaction to a file
294 : : * so that we can get the last LSN of the transaction to judge whether to
295 : : * skip before starting to apply the change.
296 : : *
297 : : * One might think that we could allow parallelism if the first lsn of the
298 : : * transaction is greater than skiplsn, but we don't send it with the
299 : : * STREAM START message, and it doesn't seem worth sending the extra eight
300 : : * bytes with the STREAM START to enable parallelism for this case.
301 : : */
302 [ - + ]: 31 : if (!XLogRecPtrIsInvalid(MySubscription->skiplsn))
461 akapila@postgresql.o 303 :UBC 0 : return false;
304 : :
305 : : /*
306 : : * For streaming transactions that are being applied using a parallel
307 : : * apply worker, we cannot decide whether to apply the change for a
308 : : * relation that is not in the READY state (see
309 : : * should_apply_changes_for_rel) as we won't know remote_final_lsn by that
310 : : * time. So, we don't start the new parallel apply worker in this case.
311 : : */
461 akapila@postgresql.o 312 [ - + ]:CBC 31 : if (!AllTablesyncsReady())
461 akapila@postgresql.o 313 :UBC 0 : return false;
314 : :
461 akapila@postgresql.o 315 :CBC 31 : return true;
316 : : }
317 : :
318 : : /*
319 : : * Set up a dynamic shared memory segment.
320 : : *
321 : : * We set up a control region that contains a fixed-size worker info
322 : : * (ParallelApplyWorkerShared), a message queue, and an error queue.
323 : : *
324 : : * Returns true on success, false on failure.
325 : : */
326 : : static bool
327 : 11 : pa_setup_dsm(ParallelApplyWorkerInfo *winfo)
328 : : {
329 : : shm_toc_estimator e;
330 : : Size segsize;
331 : : dsm_segment *seg;
332 : : shm_toc *toc;
333 : : ParallelApplyWorkerShared *shared;
334 : : shm_mq *mq;
335 : 11 : Size queue_size = DSM_QUEUE_SIZE;
336 : 11 : Size error_queue_size = DSM_ERROR_QUEUE_SIZE;
337 : :
338 : : /*
339 : : * Estimate how much shared memory we need.
340 : : *
341 : : * Because the TOC machinery may choose to insert padding of oddly-sized
342 : : * requests, we must estimate each chunk separately.
343 : : *
344 : : * We need one key to register the location of the header, and two other
345 : : * keys to track the locations of the message queue and the error message
346 : : * queue.
347 : : */
348 : 11 : shm_toc_initialize_estimator(&e);
349 : 11 : shm_toc_estimate_chunk(&e, sizeof(ParallelApplyWorkerShared));
350 : 11 : shm_toc_estimate_chunk(&e, queue_size);
351 : 11 : shm_toc_estimate_chunk(&e, error_queue_size);
352 : :
353 : 11 : shm_toc_estimate_keys(&e, 3);
354 : 11 : segsize = shm_toc_estimate(&e);
355 : :
356 : : /* Create the shared memory segment and establish a table of contents. */
357 : 11 : seg = dsm_create(shm_toc_estimate(&e), 0);
358 [ - + ]: 11 : if (!seg)
461 akapila@postgresql.o 359 :UBC 0 : return false;
360 : :
461 akapila@postgresql.o 361 :CBC 11 : toc = shm_toc_create(PG_LOGICAL_APPLY_SHM_MAGIC, dsm_segment_address(seg),
362 : : segsize);
363 : :
364 : : /* Set up the header region. */
365 : 11 : shared = shm_toc_allocate(toc, sizeof(ParallelApplyWorkerShared));
366 : 11 : SpinLockInit(&shared->mutex);
367 : :
368 : 11 : shared->xact_state = PARALLEL_TRANS_UNKNOWN;
369 : 11 : pg_atomic_init_u32(&(shared->pending_stream_count), 0);
370 : 11 : shared->last_commit_end = InvalidXLogRecPtr;
371 : 11 : shared->fileset_state = FS_EMPTY;
372 : :
373 : 11 : shm_toc_insert(toc, PARALLEL_APPLY_KEY_SHARED, shared);
374 : :
375 : : /* Set up message queue for the worker. */
376 : 11 : mq = shm_mq_create(shm_toc_allocate(toc, queue_size), queue_size);
377 : 11 : shm_toc_insert(toc, PARALLEL_APPLY_KEY_MQ, mq);
378 : 11 : shm_mq_set_sender(mq, MyProc);
379 : :
380 : : /* Attach the queue. */
381 : 11 : winfo->mq_handle = shm_mq_attach(mq, seg, NULL);
382 : :
383 : : /* Set up error queue for the worker. */
384 : 11 : mq = shm_mq_create(shm_toc_allocate(toc, error_queue_size),
385 : : error_queue_size);
386 : 11 : shm_toc_insert(toc, PARALLEL_APPLY_KEY_ERROR_QUEUE, mq);
387 : 11 : shm_mq_set_receiver(mq, MyProc);
388 : :
389 : : /* Attach the queue. */
390 : 11 : winfo->error_mq_handle = shm_mq_attach(mq, seg, NULL);
391 : :
392 : : /* Return results to caller. */
393 : 11 : winfo->dsm_seg = seg;
394 : 11 : winfo->shared = shared;
395 : :
396 : 11 : return true;
397 : : }
398 : :
399 : : /*
400 : : * Try to get a parallel apply worker from the pool. If none is available then
401 : : * start a new one.
402 : : */
403 : : static ParallelApplyWorkerInfo *
404 : 31 : pa_launch_parallel_worker(void)
405 : : {
406 : : MemoryContext oldcontext;
407 : : bool launched;
408 : : ParallelApplyWorkerInfo *winfo;
409 : : ListCell *lc;
410 : :
411 : : /* Try to get an available parallel apply worker from the worker pool. */
412 [ + + + + : 33 : foreach(lc, ParallelApplyWorkerPool)
+ + ]
413 : : {
414 : 22 : winfo = (ParallelApplyWorkerInfo *) lfirst(lc);
415 : :
416 [ + + ]: 22 : if (!winfo->in_use)
417 : 20 : return winfo;
418 : : }
419 : :
420 : : /*
421 : : * Start a new parallel apply worker.
422 : : *
423 : : * The worker info can be used for the lifetime of the worker process, so
424 : : * create it in a permanent context.
425 : : */
426 : 11 : oldcontext = MemoryContextSwitchTo(ApplyContext);
427 : :
428 : 11 : winfo = (ParallelApplyWorkerInfo *) palloc0(sizeof(ParallelApplyWorkerInfo));
429 : :
430 : : /* Setup shared memory. */
431 [ - + ]: 11 : if (!pa_setup_dsm(winfo))
432 : : {
461 akapila@postgresql.o 433 :UBC 0 : MemoryContextSwitchTo(oldcontext);
434 : 0 : pfree(winfo);
435 : 0 : return NULL;
436 : : }
437 : :
244 akapila@postgresql.o 438 :GNC 11 : launched = logicalrep_worker_launch(WORKERTYPE_PARALLEL_APPLY,
439 : 11 : MyLogicalRepWorker->dbid,
461 akapila@postgresql.o 440 :CBC 11 : MySubscription->oid,
441 : 11 : MySubscription->name,
442 : 11 : MyLogicalRepWorker->userid,
443 : : InvalidOid,
444 : : dsm_segment_handle(winfo->dsm_seg));
445 : :
446 [ + - ]: 11 : if (launched)
447 : : {
448 : 11 : ParallelApplyWorkerPool = lappend(ParallelApplyWorkerPool, winfo);
449 : : }
450 : : else
451 : : {
461 akapila@postgresql.o 452 :UBC 0 : pa_free_worker_info(winfo);
453 : 0 : winfo = NULL;
454 : : }
455 : :
461 akapila@postgresql.o 456 :CBC 11 : MemoryContextSwitchTo(oldcontext);
457 : :
458 : 11 : return winfo;
459 : : }
460 : :
461 : : /*
462 : : * Allocate a parallel apply worker that will be used for the specified xid.
463 : : *
464 : : * We first try to get an available worker from the pool, if any and then try
465 : : * to launch a new worker. On successful allocation, remember the worker
466 : : * information in the hash table so that we can get it later for processing the
467 : : * streaming changes.
468 : : */
469 : : void
470 : 95 : pa_allocate_worker(TransactionId xid)
471 : : {
472 : : bool found;
473 : 95 : ParallelApplyWorkerInfo *winfo = NULL;
474 : : ParallelApplyWorkerEntry *entry;
475 : :
476 [ + + ]: 95 : if (!pa_can_start())
477 : 64 : return;
478 : :
457 479 : 31 : winfo = pa_launch_parallel_worker();
480 [ - + ]: 31 : if (!winfo)
457 akapila@postgresql.o 481 :UBC 0 : return;
482 : :
483 : : /* First time through, initialize parallel apply worker state hashtable. */
461 akapila@postgresql.o 484 [ + + ]:CBC 31 : if (!ParallelApplyTxnHash)
485 : : {
486 : : HASHCTL ctl;
487 : :
488 [ + - + - : 104 : MemSet(&ctl, 0, sizeof(ctl));
+ - + - +
+ ]
489 : 8 : ctl.keysize = sizeof(TransactionId);
490 : 8 : ctl.entrysize = sizeof(ParallelApplyWorkerEntry);
491 : 8 : ctl.hcxt = ApplyContext;
492 : :
493 : 8 : ParallelApplyTxnHash = hash_create("logical replication parallel apply workers hash",
494 : : 16, &ctl,
495 : : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
496 : : }
497 : :
498 : : /* Create an entry for the requested transaction. */
499 : 31 : entry = hash_search(ParallelApplyTxnHash, &xid, HASH_ENTER, &found);
500 [ - + ]: 31 : if (found)
461 akapila@postgresql.o 501 [ # # ]:UBC 0 : elog(ERROR, "hash table corrupted");
502 : :
503 : : /* Update the transaction information in shared memory. */
461 akapila@postgresql.o 504 [ - + ]:CBC 31 : SpinLockAcquire(&winfo->shared->mutex);
505 : 31 : winfo->shared->xact_state = PARALLEL_TRANS_UNKNOWN;
506 : 31 : winfo->shared->xid = xid;
507 : 31 : SpinLockRelease(&winfo->shared->mutex);
508 : :
509 : 31 : winfo->in_use = true;
510 : 31 : winfo->serialize_changes = false;
511 : 31 : entry->winfo = winfo;
512 : : }
513 : :
514 : : /*
515 : : * Find the assigned worker for the given transaction, if any.
516 : : */
517 : : ParallelApplyWorkerInfo *
518 : 260384 : pa_find_worker(TransactionId xid)
519 : : {
520 : : bool found;
521 : : ParallelApplyWorkerEntry *entry;
522 : :
523 [ + + ]: 260384 : if (!TransactionIdIsValid(xid))
524 : 83057 : return NULL;
525 : :
526 [ + + ]: 177327 : if (!ParallelApplyTxnHash)
527 : 103310 : return NULL;
528 : :
529 : : /* Return the cached parallel apply worker if valid. */
530 [ + + ]: 74017 : if (stream_apply_worker)
531 : 73697 : return stream_apply_worker;
532 : :
533 : : /* Find an entry for the requested transaction. */
534 : 320 : entry = hash_search(ParallelApplyTxnHash, &xid, HASH_FIND, &found);
535 [ + - ]: 320 : if (found)
536 : : {
537 : : /* The worker must not have exited. */
538 [ - + ]: 320 : Assert(entry->winfo->in_use);
539 : 320 : return entry->winfo;
540 : : }
541 : :
461 akapila@postgresql.o 542 :UBC 0 : return NULL;
543 : : }
544 : :
545 : : /*
546 : : * Makes the worker available for reuse.
547 : : *
548 : : * This removes the parallel apply worker entry from the hash table so that it
549 : : * can't be used. If there are enough workers in the pool, it stops the worker
550 : : * and frees the corresponding info. Otherwise it just marks the worker as
551 : : * available for reuse.
552 : : *
553 : : * For more information about the worker pool, see comments atop this file.
554 : : */
555 : : static void
461 akapila@postgresql.o 556 :CBC 28 : pa_free_worker(ParallelApplyWorkerInfo *winfo)
557 : : {
558 [ - + ]: 28 : Assert(!am_parallel_apply_worker());
559 [ - + ]: 28 : Assert(winfo->in_use);
560 [ - + ]: 28 : Assert(pa_get_xact_state(winfo->shared) == PARALLEL_TRANS_FINISHED);
561 : :
562 [ - + ]: 28 : if (!hash_search(ParallelApplyTxnHash, &winfo->shared->xid, HASH_REMOVE, NULL))
461 akapila@postgresql.o 563 [ # # ]:UBC 0 : elog(ERROR, "hash table corrupted");
564 : :
565 : : /*
566 : : * Stop the worker if there are enough workers in the pool.
567 : : *
568 : : * XXX Additionally, we also stop the worker if the leader apply worker
569 : : * serialize part of the transaction data due to a send timeout. This is
570 : : * because the message could be partially written to the queue and there
571 : : * is no way to clean the queue other than resending the message until it
572 : : * succeeds. Instead of trying to send the data which anyway would have
573 : : * been serialized and then letting the parallel apply worker deal with
574 : : * the spurious message, we stop the worker.
575 : : */
461 akapila@postgresql.o 576 [ + + ]:CBC 28 : if (winfo->serialize_changes ||
577 : 24 : list_length(ParallelApplyWorkerPool) >
578 [ + + ]: 24 : (max_parallel_apply_workers_per_subscription / 2))
579 : : {
341 580 : 5 : logicalrep_pa_worker_stop(winfo);
461 581 : 5 : pa_free_worker_info(winfo);
582 : :
583 : 5 : return;
584 : : }
585 : :
586 : 23 : winfo->in_use = false;
587 : 23 : winfo->serialize_changes = false;
588 : : }
589 : :
590 : : /*
591 : : * Free the parallel apply worker information and unlink the files with
592 : : * serialized changes if any.
593 : : */
594 : : static void
595 : 5 : pa_free_worker_info(ParallelApplyWorkerInfo *winfo)
596 : : {
597 [ - + ]: 5 : Assert(winfo);
598 : :
599 [ + - ]: 5 : if (winfo->mq_handle)
600 : 5 : shm_mq_detach(winfo->mq_handle);
601 : :
602 [ - + ]: 5 : if (winfo->error_mq_handle)
461 akapila@postgresql.o 603 :UBC 0 : shm_mq_detach(winfo->error_mq_handle);
604 : :
605 : : /* Unlink the files with serialized changes. */
461 akapila@postgresql.o 606 [ + + ]:CBC 5 : if (winfo->serialize_changes)
607 : 4 : stream_cleanup_files(MyLogicalRepWorker->subid, winfo->shared->xid);
608 : :
609 [ + - ]: 5 : if (winfo->dsm_seg)
610 : 5 : dsm_detach(winfo->dsm_seg);
611 : :
612 : : /* Remove from the worker pool. */
613 : 5 : ParallelApplyWorkerPool = list_delete_ptr(ParallelApplyWorkerPool, winfo);
614 : :
615 : 5 : pfree(winfo);
616 : 5 : }
617 : :
618 : : /*
619 : : * Detach the error queue for all parallel apply workers.
620 : : */
621 : : void
622 : 263 : pa_detach_all_error_mq(void)
623 : : {
624 : : ListCell *lc;
625 : :
626 [ + + + + : 268 : foreach(lc, ParallelApplyWorkerPool)
+ + ]
627 : : {
628 : 5 : ParallelApplyWorkerInfo *winfo = (ParallelApplyWorkerInfo *) lfirst(lc);
629 : :
341 630 [ + - ]: 5 : if (winfo->error_mq_handle)
631 : : {
632 : 5 : shm_mq_detach(winfo->error_mq_handle);
633 : 5 : winfo->error_mq_handle = NULL;
634 : : }
635 : : }
461 636 : 263 : }
637 : :
638 : : /*
639 : : * Check if there are any pending spooled messages.
640 : : */
641 : : static bool
642 : 16 : pa_has_spooled_message_pending()
643 : : {
644 : : PartialFileSetState fileset_state;
645 : :
646 : 16 : fileset_state = pa_get_fileset_state();
647 : :
648 : 16 : return (fileset_state != FS_EMPTY);
649 : : }
650 : :
651 : : /*
652 : : * Replay the spooled messages once the leader apply worker has finished
653 : : * serializing changes to the file.
654 : : *
655 : : * Returns false if there aren't any pending spooled messages, true otherwise.
656 : : */
657 : : static bool
658 : 63 : pa_process_spooled_messages_if_required(void)
659 : : {
660 : : PartialFileSetState fileset_state;
661 : :
662 : 63 : fileset_state = pa_get_fileset_state();
663 : :
664 [ + + ]: 63 : if (fileset_state == FS_EMPTY)
665 : 55 : return false;
666 : :
667 : : /*
668 : : * If the leader apply worker is busy serializing the partial changes then
669 : : * acquire the stream lock now and wait for the leader worker to finish
670 : : * serializing the changes. Otherwise, the parallel apply worker won't get
671 : : * a chance to receive a STREAM_STOP (and acquire the stream lock) until
672 : : * the leader had serialized all changes which can lead to undetected
673 : : * deadlock.
674 : : *
675 : : * Note that the fileset state can be FS_SERIALIZE_DONE once the leader
676 : : * worker has finished serializing the changes.
677 : : */
678 [ - + ]: 8 : if (fileset_state == FS_SERIALIZE_IN_PROGRESS)
679 : : {
461 akapila@postgresql.o 680 :UBC 0 : pa_lock_stream(MyParallelShared->xid, AccessShareLock);
681 : 0 : pa_unlock_stream(MyParallelShared->xid, AccessShareLock);
682 : :
683 : 0 : fileset_state = pa_get_fileset_state();
684 : : }
685 : :
686 : : /*
687 : : * We cannot read the file immediately after the leader has serialized all
688 : : * changes to the file because there may still be messages in the memory
689 : : * queue. We will apply all spooled messages the next time we call this
690 : : * function and that will ensure there are no messages left in the memory
691 : : * queue.
692 : : */
461 akapila@postgresql.o 693 [ + + ]:CBC 8 : if (fileset_state == FS_SERIALIZE_DONE)
694 : : {
695 : 4 : pa_set_fileset_state(MyParallelShared, FS_READY);
696 : : }
697 [ + - ]: 4 : else if (fileset_state == FS_READY)
698 : : {
699 : 4 : apply_spooled_messages(&MyParallelShared->fileset,
700 : 4 : MyParallelShared->xid,
701 : : InvalidXLogRecPtr);
702 : 4 : pa_set_fileset_state(MyParallelShared, FS_EMPTY);
703 : : }
704 : :
705 : 8 : return true;
706 : : }
707 : :
708 : : /*
709 : : * Interrupt handler for main loop of parallel apply worker.
710 : : */
711 : : static void
712 : 64026 : ProcessParallelApplyInterrupts(void)
713 : : {
714 [ + + ]: 64026 : CHECK_FOR_INTERRUPTS();
715 : :
716 [ + + ]: 64023 : if (ShutdownRequestPending)
717 : : {
718 [ + - ]: 5 : ereport(LOG,
719 : : (errmsg("logical replication parallel apply worker for subscription \"%s\" has finished",
720 : : MySubscription->name)));
721 : :
722 : 5 : proc_exit(0);
723 : : }
724 : :
725 [ + + ]: 64018 : if (ConfigReloadPending)
726 : : {
727 : 4 : ConfigReloadPending = false;
728 : 4 : ProcessConfigFile(PGC_SIGHUP);
729 : : }
730 : 64018 : }
731 : :
732 : : /* Parallel apply worker main loop. */
733 : : static void
734 : 11 : LogicalParallelApplyLoop(shm_mq_handle *mqh)
735 : : {
736 : : shm_mq_result shmq_res;
737 : : ErrorContextCallback errcallback;
738 : 11 : MemoryContext oldcxt = CurrentMemoryContext;
739 : :
740 : : /*
741 : : * Init the ApplyMessageContext which we clean up after each replication
742 : : * protocol message.
743 : : */
744 : 11 : ApplyMessageContext = AllocSetContextCreate(ApplyContext,
745 : : "ApplyMessageContext",
746 : : ALLOCSET_DEFAULT_SIZES);
747 : :
748 : : /*
749 : : * Push apply error context callback. Fields will be filled while applying
750 : : * a change.
751 : : */
752 : 11 : errcallback.callback = apply_error_callback;
753 : 11 : errcallback.previous = error_context_stack;
754 : 11 : error_context_stack = &errcallback;
755 : :
756 : : for (;;)
757 : 64015 : {
758 : : void *data;
759 : : Size len;
760 : :
761 : 64026 : ProcessParallelApplyInterrupts();
762 : :
763 : : /* Ensure we are reading the data into our memory context. */
764 : 64018 : MemoryContextSwitchTo(ApplyMessageContext);
765 : :
766 : 64018 : shmq_res = shm_mq_receive(mqh, &len, &data, true);
767 : :
768 [ + + ]: 64018 : if (shmq_res == SHM_MQ_SUCCESS)
769 : : {
770 : : StringInfoData s;
771 : : int c;
772 : :
773 [ - + ]: 63955 : if (len == 0)
461 akapila@postgresql.o 774 [ # # ]:UBC 0 : elog(ERROR, "invalid message length");
775 : :
171 drowley@postgresql.o 776 :GNC 63955 : initReadOnlyStringInfo(&s, data, len);
777 : :
778 : : /*
779 : : * The first byte of messages sent from leader apply worker to
780 : : * parallel apply workers can only be 'w'.
781 : : */
461 akapila@postgresql.o 782 :CBC 63955 : c = pq_getmsgbyte(&s);
783 [ - + ]: 63955 : if (c != 'w')
461 akapila@postgresql.o 784 [ # # ]:UBC 0 : elog(ERROR, "unexpected message \"%c\"", c);
785 : :
786 : : /*
787 : : * Ignore statistics fields that have been updated by the leader
788 : : * apply worker.
789 : : *
790 : : * XXX We can avoid sending the statistics fields from the leader
791 : : * apply worker but for that, it needs to rebuild the entire
792 : : * message by removing these fields which could be more work than
793 : : * simply ignoring these fields in the parallel apply worker.
794 : : */
461 akapila@postgresql.o 795 :CBC 63955 : s.cursor += SIZE_STATS_MESSAGE;
796 : :
797 : 63955 : apply_dispatch(&s);
798 : : }
799 [ + - ]: 63 : else if (shmq_res == SHM_MQ_WOULD_BLOCK)
800 : : {
801 : : /* Replay the changes from the file, if any. */
802 [ + + ]: 63 : if (!pa_process_spooled_messages_if_required())
803 : : {
804 : : int rc;
805 : :
806 : : /* Wait for more work. */
807 : 55 : rc = WaitLatch(MyLatch,
808 : : WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
809 : : 1000L,
810 : : WAIT_EVENT_LOGICAL_PARALLEL_APPLY_MAIN);
811 : :
812 [ + + ]: 54 : if (rc & WL_LATCH_SET)
813 : 52 : ResetLatch(MyLatch);
814 : : }
815 : : }
816 : : else
817 : : {
461 akapila@postgresql.o 818 [ # # ]:UBC 0 : Assert(shmq_res == SHM_MQ_DETACHED);
819 : :
820 [ # # ]: 0 : ereport(ERROR,
821 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
822 : : errmsg("lost connection to the logical replication apply worker")));
823 : : }
824 : :
461 akapila@postgresql.o 825 :CBC 64015 : MemoryContextReset(ApplyMessageContext);
826 : 64015 : MemoryContextSwitchTo(oldcxt);
827 : : }
828 : :
829 : : /* Pop the error context stack. */
830 : : error_context_stack = errcallback.previous;
831 : :
832 : : MemoryContextSwitchTo(oldcxt);
833 : : }
834 : :
835 : : /*
836 : : * Make sure the leader apply worker tries to read from our error queue one more
837 : : * time. This guards against the case where we exit uncleanly without sending
838 : : * an ErrorResponse, for example because some code calls proc_exit directly.
839 : : *
840 : : * Also explicitly detach from dsm segment to invoke on_dsm_detach callbacks,
841 : : * if any. See ParallelWorkerShutdown for details.
842 : : */
843 : : static void
844 : 10 : pa_shutdown(int code, Datum arg)
845 : : {
452 846 : 10 : SendProcSignal(MyLogicalRepWorker->leader_pid,
847 : : PROCSIG_PARALLEL_APPLY_MESSAGE,
848 : : INVALID_PROC_NUMBER);
849 : :
461 850 : 10 : dsm_detach((dsm_segment *) DatumGetPointer(arg));
851 : 10 : }
852 : :
853 : : /*
854 : : * Parallel apply worker entry point.
855 : : */
856 : : void
857 : 11 : ParallelApplyWorkerMain(Datum main_arg)
858 : : {
859 : : ParallelApplyWorkerShared *shared;
860 : : dsm_handle handle;
861 : : dsm_segment *seg;
862 : : shm_toc *toc;
863 : : shm_mq *mq;
864 : : shm_mq_handle *mqh;
865 : : shm_mq_handle *error_mqh;
866 : : RepOriginId originid;
867 : 11 : int worker_slot = DatumGetInt32(main_arg);
868 : : char originname[NAMEDATALEN];
869 : :
347 870 : 11 : InitializingApplyWorker = true;
871 : :
872 : : /* Setup signal handling. */
461 873 : 11 : pqsignal(SIGHUP, SignalHandlerForConfigReload);
874 : 11 : pqsignal(SIGINT, SignalHandlerForShutdownRequest);
875 : 11 : pqsignal(SIGTERM, die);
876 : 11 : BackgroundWorkerUnblockSignals();
877 : :
878 : : /*
879 : : * Attach to the dynamic shared memory segment for the parallel apply, and
880 : : * find its table of contents.
881 : : *
882 : : * Like parallel query, we don't need resource owner by this time. See
883 : : * ParallelWorkerMain.
884 : : */
885 : 11 : memcpy(&handle, MyBgworkerEntry->bgw_extra, sizeof(dsm_handle));
886 : 11 : seg = dsm_attach(handle);
887 [ - + ]: 11 : if (!seg)
461 akapila@postgresql.o 888 [ # # ]:UBC 0 : ereport(ERROR,
889 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
890 : : errmsg("could not map dynamic shared memory segment")));
891 : :
461 akapila@postgresql.o 892 :CBC 11 : toc = shm_toc_attach(PG_LOGICAL_APPLY_SHM_MAGIC, dsm_segment_address(seg));
893 [ - + ]: 11 : if (!toc)
461 akapila@postgresql.o 894 [ # # ]:UBC 0 : ereport(ERROR,
895 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
896 : : errmsg("invalid magic number in dynamic shared memory segment")));
897 : :
898 : : /* Look up the shared information. */
461 akapila@postgresql.o 899 :CBC 11 : shared = shm_toc_lookup(toc, PARALLEL_APPLY_KEY_SHARED, false);
900 : 11 : MyParallelShared = shared;
901 : :
902 : : /*
903 : : * Attach to the message queue.
904 : : */
905 : 11 : mq = shm_toc_lookup(toc, PARALLEL_APPLY_KEY_MQ, false);
906 : 11 : shm_mq_set_receiver(mq, MyProc);
907 : 11 : mqh = shm_mq_attach(mq, seg, NULL);
908 : :
909 : : /*
910 : : * Primary initialization is complete. Now, we can attach to our slot.
911 : : * This is to ensure that the leader apply worker does not write data to
912 : : * the uninitialized memory queue.
913 : : */
914 : 11 : logicalrep_worker_attach(worker_slot);
915 : :
916 : : /*
917 : : * Register the shutdown callback after we are attached to the worker
918 : : * slot. This is to ensure that MyLogicalRepWorker remains valid when this
919 : : * callback is invoked.
920 : : */
341 921 : 11 : before_shmem_exit(pa_shutdown, PointerGetDatum(seg));
922 : :
461 923 [ - + ]: 11 : SpinLockAcquire(&MyParallelShared->mutex);
924 : 11 : MyParallelShared->logicalrep_worker_generation = MyLogicalRepWorker->generation;
925 : 11 : MyParallelShared->logicalrep_worker_slot_no = worker_slot;
926 : 11 : SpinLockRelease(&MyParallelShared->mutex);
927 : :
928 : : /*
929 : : * Attach to the error queue.
930 : : */
931 : 11 : mq = shm_toc_lookup(toc, PARALLEL_APPLY_KEY_ERROR_QUEUE, false);
932 : 11 : shm_mq_set_sender(mq, MyProc);
933 : 11 : error_mqh = shm_mq_attach(mq, seg, NULL);
934 : :
935 : 11 : pq_redirect_to_shm_mq(seg, error_mqh);
452 936 : 11 : pq_set_parallel_leader(MyLogicalRepWorker->leader_pid,
937 : : INVALID_PROC_NUMBER);
938 : :
461 939 : 11 : MyLogicalRepWorker->last_send_time = MyLogicalRepWorker->last_recv_time =
940 : 11 : MyLogicalRepWorker->reply_time = 0;
941 : :
255 akapila@postgresql.o 942 :GNC 11 : InitializeLogRepWorker();
943 : :
347 akapila@postgresql.o 944 :CBC 11 : InitializingApplyWorker = false;
945 : :
946 : : /* Setup replication origin tracking. */
461 947 : 11 : StartTransactionCommand();
948 : 11 : ReplicationOriginNameForLogicalRep(MySubscription->oid, InvalidOid,
949 : : originname, sizeof(originname));
950 : 11 : originid = replorigin_by_name(originname, false);
951 : :
952 : : /*
953 : : * The parallel apply worker doesn't need to monopolize this replication
954 : : * origin which was already acquired by its leader process.
955 : : */
452 956 : 11 : replorigin_session_setup(originid, MyLogicalRepWorker->leader_pid);
461 957 : 11 : replorigin_session_origin = originid;
958 : 11 : CommitTransactionCommand();
959 : :
960 : : /*
961 : : * Setup callback for syscache so that we know when something changes in
962 : : * the subscription relation state.
963 : : */
964 : 11 : CacheRegisterSyscacheCallback(SUBSCRIPTIONRELMAP,
965 : : invalidate_syncing_table_states,
966 : : (Datum) 0);
967 : :
968 : 11 : set_apply_error_context_origin(originname);
969 : :
970 : 11 : LogicalParallelApplyLoop(mqh);
971 : :
972 : : /*
973 : : * The parallel apply worker must not get here because the parallel apply
974 : : * worker will only stop when it receives a SIGTERM or SIGINT from the
975 : : * leader, or when there is an error. None of these cases will allow the
976 : : * code to reach here.
977 : : */
461 akapila@postgresql.o 978 :UBC 0 : Assert(false);
979 : : }
980 : :
981 : : /*
982 : : * Handle receipt of an interrupt indicating a parallel apply worker message.
983 : : *
984 : : * Note: this is called within a signal handler! All we can do is set a flag
985 : : * that will cause the next CHECK_FOR_INTERRUPTS() to invoke
986 : : * HandleParallelApplyMessages().
987 : : */
988 : : void
461 akapila@postgresql.o 989 :CBC 13 : HandleParallelApplyMessageInterrupt(void)
990 : : {
991 : 13 : InterruptPending = true;
992 : 13 : ParallelApplyMessagePending = true;
993 : 13 : SetLatch(MyLatch);
994 : 13 : }
995 : :
996 : : /*
997 : : * Handle a single protocol message received from a single parallel apply
998 : : * worker.
999 : : */
1000 : : static void
1001 : 2 : HandleParallelApplyMessage(StringInfo msg)
1002 : : {
1003 : : char msgtype;
1004 : :
1005 : 2 : msgtype = pq_getmsgbyte(msg);
1006 : :
1007 [ + - - ]: 2 : switch (msgtype)
1008 : : {
1009 : 2 : case 'E': /* ErrorResponse */
1010 : : {
1011 : : ErrorData edata;
1012 : :
1013 : : /* Parse ErrorResponse. */
1014 : 2 : pq_parse_errornotice(msg, &edata);
1015 : :
1016 : : /*
1017 : : * If desired, add a context line to show that this is a
1018 : : * message propagated from a parallel apply worker. Otherwise,
1019 : : * it can sometimes be confusing to understand what actually
1020 : : * happened.
1021 : : */
1022 [ + - ]: 2 : if (edata.context)
1023 : 2 : edata.context = psprintf("%s\n%s", edata.context,
1024 : : _("logical replication parallel apply worker"));
1025 : : else
461 akapila@postgresql.o 1026 :UBC 0 : edata.context = pstrdup(_("logical replication parallel apply worker"));
1027 : :
1028 : : /*
1029 : : * Context beyond that should use the error context callbacks
1030 : : * that were in effect in LogicalRepApplyLoop().
1031 : : */
461 akapila@postgresql.o 1032 :CBC 2 : error_context_stack = apply_error_context_stack;
1033 : :
1034 : : /*
1035 : : * The actual error must have been reported by the parallel
1036 : : * apply worker.
1037 : : */
1038 [ + - ]: 2 : ereport(ERROR,
1039 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1040 : : errmsg("logical replication parallel apply worker exited due to error"),
1041 : : errcontext("%s", edata.context)));
1042 : : }
1043 : :
1044 : : /*
1045 : : * Don't need to do anything about NoticeResponse and
1046 : : * NotifyResponse as the logical replication worker doesn't need
1047 : : * to send messages to the client.
1048 : : */
461 akapila@postgresql.o 1049 :UBC 0 : case 'N':
1050 : : case 'A':
1051 : 0 : break;
1052 : :
1053 : 0 : default:
1054 [ # # ]: 0 : elog(ERROR, "unrecognized message type received from logical replication parallel apply worker: %c (message length %d bytes)",
1055 : : msgtype, msg->len);
1056 : : }
1057 : 0 : }
1058 : :
1059 : : /*
1060 : : * Handle any queued protocol messages received from parallel apply workers.
1061 : : */
1062 : : void
461 akapila@postgresql.o 1063 :CBC 7 : HandleParallelApplyMessages(void)
1064 : : {
1065 : : ListCell *lc;
1066 : : MemoryContext oldcontext;
1067 : :
1068 : : static MemoryContext hpam_context = NULL;
1069 : :
1070 : : /*
1071 : : * This is invoked from ProcessInterrupts(), and since some of the
1072 : : * functions it calls contain CHECK_FOR_INTERRUPTS(), there is a potential
1073 : : * for recursive calls if more signals are received while this runs. It's
1074 : : * unclear that recursive entry would be safe, and it doesn't seem useful
1075 : : * even if it is safe, so let's block interrupts until done.
1076 : : */
1077 : 7 : HOLD_INTERRUPTS();
1078 : :
1079 : : /*
1080 : : * Moreover, CurrentMemoryContext might be pointing almost anywhere. We
1081 : : * don't want to risk leaking data into long-lived contexts, so let's do
1082 : : * our work here in a private context that we can reset on each use.
1083 : : */
1084 [ + + ]: 7 : if (!hpam_context) /* first time through? */
1085 : 6 : hpam_context = AllocSetContextCreate(TopMemoryContext,
1086 : : "HandleParallelApplyMessages",
1087 : : ALLOCSET_DEFAULT_SIZES);
1088 : : else
1089 : 1 : MemoryContextReset(hpam_context);
1090 : :
1091 : 7 : oldcontext = MemoryContextSwitchTo(hpam_context);
1092 : :
1093 : 7 : ParallelApplyMessagePending = false;
1094 : :
1095 [ + - + + : 13 : foreach(lc, ParallelApplyWorkerPool)
+ + ]
1096 : : {
1097 : : shm_mq_result res;
1098 : : Size nbytes;
1099 : : void *data;
1100 : 8 : ParallelApplyWorkerInfo *winfo = (ParallelApplyWorkerInfo *) lfirst(lc);
1101 : :
1102 : : /*
1103 : : * The leader will detach from the error queue and set it to NULL
1104 : : * before preparing to stop all parallel apply workers, so we don't
1105 : : * need to handle error messages anymore. See
1106 : : * logicalrep_worker_detach.
1107 : : */
1108 [ + + ]: 8 : if (!winfo->error_mq_handle)
1109 : 6 : continue;
1110 : :
1111 : 3 : res = shm_mq_receive(winfo->error_mq_handle, &nbytes, &data, true);
1112 : :
1113 [ + + ]: 3 : if (res == SHM_MQ_WOULD_BLOCK)
1114 : 1 : continue;
1115 [ + - ]: 2 : else if (res == SHM_MQ_SUCCESS)
1116 : : {
1117 : : StringInfoData msg;
1118 : :
1119 : 2 : initStringInfo(&msg);
1120 : 2 : appendBinaryStringInfo(&msg, data, nbytes);
1121 : 2 : HandleParallelApplyMessage(&msg);
461 akapila@postgresql.o 1122 :UBC 0 : pfree(msg.data);
1123 : : }
1124 : : else
1125 [ # # ]: 0 : ereport(ERROR,
1126 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1127 : : errmsg("lost connection to the logical replication parallel apply worker")));
1128 : : }
1129 : :
461 akapila@postgresql.o 1130 :CBC 5 : MemoryContextSwitchTo(oldcontext);
1131 : :
1132 : : /* Might as well clear the context on our way out */
1133 : 5 : MemoryContextReset(hpam_context);
1134 : :
1135 [ - + ]: 5 : RESUME_INTERRUPTS();
1136 : 5 : }
1137 : :
1138 : : /*
1139 : : * Send the data to the specified parallel apply worker via shared-memory
1140 : : * queue.
1141 : : *
1142 : : * Returns false if the attempt to send data via shared memory times out, true
1143 : : * otherwise.
1144 : : */
1145 : : bool
1146 : 68980 : pa_send_data(ParallelApplyWorkerInfo *winfo, Size nbytes, const void *data)
1147 : : {
1148 : : int rc;
1149 : : shm_mq_result result;
1150 : 68980 : TimestampTz startTime = 0;
1151 : :
1152 [ - + ]: 68980 : Assert(!IsTransactionState());
1153 [ - + ]: 68980 : Assert(!winfo->serialize_changes);
1154 : :
1155 : : /*
1156 : : * We don't try to send data to parallel worker for 'immediate' mode. This
1157 : : * is primarily used for testing purposes.
1158 : : */
229 peter@eisentraut.org 1159 [ + + ]: 68980 : if (unlikely(debug_logical_replication_streaming == DEBUG_LOGICAL_REP_STREAMING_IMMEDIATE))
437 akapila@postgresql.o 1160 : 4 : return false;
1161 : :
1162 : : /*
1163 : : * This timeout is a bit arbitrary but testing revealed that it is sufficient
1164 : : * to send the message unless the parallel apply worker is waiting on some
1165 : : * lock or there is a serious resource crunch. See the comments atop this file
1166 : : * to know why we are using a non-blocking way to send the message.
1167 : : */
1168 : : #define SHM_SEND_RETRY_INTERVAL_MS 1000
1169 : : #define SHM_SEND_TIMEOUT_MS (10000 - SHM_SEND_RETRY_INTERVAL_MS)
1170 : :
1171 : : for (;;)
1172 : : {
461 akapila@postgresql.o 1173 :UBC 0 : result = shm_mq_send(winfo->mq_handle, nbytes, data, true, true);
1174 : :
461 akapila@postgresql.o 1175 [ + - ]:CBC 68976 : if (result == SHM_MQ_SUCCESS)
1176 : 68976 : return true;
461 akapila@postgresql.o 1177 [ # # ]:UBC 0 : else if (result == SHM_MQ_DETACHED)
1178 [ # # ]: 0 : ereport(ERROR,
1179 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1180 : : errmsg("could not send data to shared-memory queue")));
1181 : :
1182 [ # # ]: 0 : Assert(result == SHM_MQ_WOULD_BLOCK);
1183 : :
1184 : : /* Wait before retrying. */
1185 : 0 : rc = WaitLatch(MyLatch,
1186 : : WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
1187 : : SHM_SEND_RETRY_INTERVAL_MS,
1188 : : WAIT_EVENT_LOGICAL_APPLY_SEND_DATA);
1189 : :
1190 [ # # ]: 0 : if (rc & WL_LATCH_SET)
1191 : : {
1192 : 0 : ResetLatch(MyLatch);
1193 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
1194 : : }
1195 : :
1196 [ # # ]: 0 : if (startTime == 0)
1197 : 0 : startTime = GetCurrentTimestamp();
1198 [ # # ]: 0 : else if (TimestampDifferenceExceeds(startTime, GetCurrentTimestamp(),
1199 : : SHM_SEND_TIMEOUT_MS))
1200 : 0 : return false;
1201 : : }
1202 : : }
1203 : :
1204 : : /*
1205 : : * Switch to PARTIAL_SERIALIZE mode for the current transaction -- this means
1206 : : * that the current data and any subsequent data for this transaction will be
1207 : : * serialized to a file. This is done to prevent possible deadlocks with
1208 : : * another parallel apply worker (refer to the comments atop this file).
1209 : : */
1210 : : void
461 akapila@postgresql.o 1211 :CBC 4 : pa_switch_to_partial_serialize(ParallelApplyWorkerInfo *winfo,
1212 : : bool stream_locked)
1213 : : {
437 1214 [ + - ]: 4 : ereport(LOG,
1215 : : (errmsg("logical replication apply worker will serialize the remaining changes of remote transaction %u to a file",
1216 : : winfo->shared->xid)));
1217 : :
1218 : : /*
1219 : : * The parallel apply worker could be stuck for some reason (say waiting
1220 : : * on some lock by other backend), so stop trying to send data directly to
1221 : : * it and start serializing data to the file instead.
1222 : : */
461 1223 : 4 : winfo->serialize_changes = true;
1224 : :
1225 : : /* Initialize the stream fileset. */
1226 : 4 : stream_start_internal(winfo->shared->xid, true);
1227 : :
1228 : : /*
1229 : : * Acquires the stream lock if not already to make sure that the parallel
1230 : : * apply worker will wait for the leader to release the stream lock until
1231 : : * the end of the transaction.
1232 : : */
1233 [ + - ]: 4 : if (!stream_locked)
1234 : 4 : pa_lock_stream(winfo->shared->xid, AccessExclusiveLock);
1235 : :
1236 : 4 : pa_set_fileset_state(winfo->shared, FS_SERIALIZE_IN_PROGRESS);
1237 : 4 : }
1238 : :
1239 : : /*
1240 : : * Wait until the parallel apply worker's transaction state has reached or
1241 : : * exceeded the given xact_state.
1242 : : */
1243 : : static void
1244 : 29 : pa_wait_for_xact_state(ParallelApplyWorkerInfo *winfo,
1245 : : ParallelTransState xact_state)
1246 : : {
1247 : : for (;;)
1248 : : {
1249 : : /*
1250 : : * Stop if the transaction state has reached or exceeded the given
1251 : : * xact_state.
1252 : : */
1253 [ + + ]: 258 : if (pa_get_xact_state(winfo->shared) >= xact_state)
1254 : 29 : break;
1255 : :
1256 : : /* Wait to be signalled. */
1257 : 229 : (void) WaitLatch(MyLatch,
1258 : : WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
1259 : : 10L,
1260 : : WAIT_EVENT_LOGICAL_PARALLEL_APPLY_STATE_CHANGE);
1261 : :
1262 : : /* Reset the latch so we don't spin. */
1263 : 229 : ResetLatch(MyLatch);
1264 : :
1265 : : /* An interrupt may have occurred while we were waiting. */
1266 [ - + ]: 229 : CHECK_FOR_INTERRUPTS();
1267 : : }
1268 : 29 : }
1269 : :
1270 : : /*
1271 : : * Wait until the parallel apply worker's transaction finishes.
1272 : : */
1273 : : static void
1274 : 29 : pa_wait_for_xact_finish(ParallelApplyWorkerInfo *winfo)
1275 : : {
1276 : : /*
1277 : : * Wait until the parallel apply worker set the state to
1278 : : * PARALLEL_TRANS_STARTED which means it has acquired the transaction
1279 : : * lock. This is to prevent leader apply worker from acquiring the
1280 : : * transaction lock earlier than the parallel apply worker.
1281 : : */
1282 : 29 : pa_wait_for_xact_state(winfo, PARALLEL_TRANS_STARTED);
1283 : :
1284 : : /*
1285 : : * Wait for the transaction lock to be released. This is required to
1286 : : * detect deadlock among leader and parallel apply workers. Refer to the
1287 : : * comments atop this file.
1288 : : */
1289 : 29 : pa_lock_transaction(winfo->shared->xid, AccessShareLock);
1290 : 28 : pa_unlock_transaction(winfo->shared->xid, AccessShareLock);
1291 : :
1292 : : /*
1293 : : * Check if the state becomes PARALLEL_TRANS_FINISHED in case the parallel
1294 : : * apply worker failed while applying changes causing the lock to be
1295 : : * released.
1296 : : */
1297 [ - + ]: 28 : if (pa_get_xact_state(winfo->shared) != PARALLEL_TRANS_FINISHED)
461 akapila@postgresql.o 1298 [ # # ]:UBC 0 : ereport(ERROR,
1299 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1300 : : errmsg("lost connection to the logical replication parallel apply worker")));
461 akapila@postgresql.o 1301 :CBC 28 : }
1302 : :
1303 : : /*
1304 : : * Set the transaction state for a given parallel apply worker.
1305 : : */
1306 : : void
1307 : 59 : pa_set_xact_state(ParallelApplyWorkerShared *wshared,
1308 : : ParallelTransState xact_state)
1309 : : {
1310 [ - + ]: 59 : SpinLockAcquire(&wshared->mutex);
1311 : 59 : wshared->xact_state = xact_state;
1312 : 59 : SpinLockRelease(&wshared->mutex);
1313 : 59 : }
1314 : :
1315 : : /*
1316 : : * Get the transaction state for a given parallel apply worker.
1317 : : */
1318 : : static ParallelTransState
1319 : 314 : pa_get_xact_state(ParallelApplyWorkerShared *wshared)
1320 : : {
1321 : : ParallelTransState xact_state;
1322 : :
1323 [ - + ]: 314 : SpinLockAcquire(&wshared->mutex);
1324 : 314 : xact_state = wshared->xact_state;
1325 : 314 : SpinLockRelease(&wshared->mutex);
1326 : :
1327 : 314 : return xact_state;
1328 : : }
1329 : :
1330 : : /*
1331 : : * Cache the parallel apply worker information.
1332 : : */
1333 : : void
1334 : 562 : pa_set_stream_apply_worker(ParallelApplyWorkerInfo *winfo)
1335 : : {
1336 : 562 : stream_apply_worker = winfo;
1337 : 562 : }
1338 : :
1339 : : /*
1340 : : * Form a unique savepoint name for the streaming transaction.
1341 : : *
1342 : : * Note that different subscriptions for publications on different nodes can
1343 : : * receive same remote xid, so we need to use subscription id along with it.
1344 : : *
1345 : : * Returns the name in the supplied buffer.
1346 : : */
1347 : : static void
1348 : 27 : pa_savepoint_name(Oid suboid, TransactionId xid, char *spname, Size szsp)
1349 : : {
1350 : 27 : snprintf(spname, szsp, "pg_sp_%u_%u", suboid, xid);
1351 : 27 : }
1352 : :
1353 : : /*
1354 : : * Define a savepoint for a subxact in parallel apply worker if needed.
1355 : : *
1356 : : * The parallel apply worker can figure out if a new subtransaction was
1357 : : * started by checking if the new change arrived with a different xid. In that
1358 : : * case define a named savepoint, so that we are able to rollback to it
1359 : : * if required.
1360 : : */
1361 : : void
1362 : 68417 : pa_start_subtrans(TransactionId current_xid, TransactionId top_xid)
1363 : : {
1364 [ + + ]: 68417 : if (current_xid != top_xid &&
1365 [ + + ]: 52 : !list_member_xid(subxactlist, current_xid))
1366 : : {
1367 : : MemoryContext oldctx;
1368 : : char spname[NAMEDATALEN];
1369 : :
1370 : 17 : pa_savepoint_name(MySubscription->oid, current_xid,
1371 : : spname, sizeof(spname));
1372 : :
1373 [ + + ]: 17 : elog(DEBUG1, "defining savepoint %s in logical replication parallel apply worker", spname);
1374 : :
1375 : : /* We must be in transaction block to define the SAVEPOINT. */
1376 [ + + ]: 17 : if (!IsTransactionBlock())
1377 : : {
1378 [ - + ]: 5 : if (!IsTransactionState())
461 akapila@postgresql.o 1379 :UBC 0 : StartTransactionCommand();
1380 : :
461 akapila@postgresql.o 1381 :CBC 5 : BeginTransactionBlock();
1382 : 5 : CommitTransactionCommand();
1383 : : }
1384 : :
1385 : 17 : DefineSavepoint(spname);
1386 : :
1387 : : /*
1388 : : * CommitTransactionCommand is needed to start a subtransaction after
1389 : : * issuing a SAVEPOINT inside a transaction block (see
1390 : : * StartSubTransaction()).
1391 : : */
1392 : 17 : CommitTransactionCommand();
1393 : :
1394 : 17 : oldctx = MemoryContextSwitchTo(TopTransactionContext);
1395 : 17 : subxactlist = lappend_xid(subxactlist, current_xid);
1396 : 17 : MemoryContextSwitchTo(oldctx);
1397 : : }
1398 : 68417 : }
1399 : :
1400 : : /* Reset the list that maintains subtransactions. */
1401 : : void
1402 : 28 : pa_reset_subtrans(void)
1403 : : {
1404 : : /*
1405 : : * We don't need to free this explicitly as the allocated memory will be
1406 : : * freed at the transaction end.
1407 : : */
1408 : 28 : subxactlist = NIL;
1409 : 28 : }
1410 : :
1411 : : /*
1412 : : * Handle STREAM ABORT message when the transaction was applied in a parallel
1413 : : * apply worker.
1414 : : */
1415 : : void
1416 : 12 : pa_stream_abort(LogicalRepStreamAbortData *abort_data)
1417 : : {
1418 : 12 : TransactionId xid = abort_data->xid;
1419 : 12 : TransactionId subxid = abort_data->subxid;
1420 : :
1421 : : /*
1422 : : * Update origin state so we can restart streaming from correct position
1423 : : * in case of crash.
1424 : : */
1425 : 12 : replorigin_session_origin_lsn = abort_data->abort_lsn;
1426 : 12 : replorigin_session_origin_timestamp = abort_data->abort_time;
1427 : :
1428 : : /*
1429 : : * If the two XIDs are the same, it's in fact abort of toplevel xact, so
1430 : : * just free the subxactlist.
1431 : : */
1432 [ + + ]: 12 : if (subxid == xid)
1433 : : {
1434 : 2 : pa_set_xact_state(MyParallelShared, PARALLEL_TRANS_FINISHED);
1435 : :
1436 : : /*
1437 : : * Release the lock as we might be processing an empty streaming
1438 : : * transaction in which case the lock won't be released during
1439 : : * transaction rollback.
1440 : : *
1441 : : * Note that it's ok to release the transaction lock before aborting
1442 : : * the transaction because even if the parallel apply worker dies due
1443 : : * to crash or some other reason, such a transaction would still be
1444 : : * considered aborted.
1445 : : */
1446 : 2 : pa_unlock_transaction(xid, AccessExclusiveLock);
1447 : :
1448 : 2 : AbortCurrentTransaction();
1449 : :
1450 [ + + ]: 2 : if (IsTransactionBlock())
1451 : : {
1452 : 1 : EndTransactionBlock(false);
1453 : 1 : CommitTransactionCommand();
1454 : : }
1455 : :
1456 : 2 : pa_reset_subtrans();
1457 : :
1458 : 2 : pgstat_report_activity(STATE_IDLE, NULL);
1459 : : }
1460 : : else
1461 : : {
1462 : : /* OK, so it's a subxact. Rollback to the savepoint. */
1463 : : int i;
1464 : : char spname[NAMEDATALEN];
1465 : :
1466 : 10 : pa_savepoint_name(MySubscription->oid, subxid, spname, sizeof(spname));
1467 : :
1468 [ + + ]: 10 : elog(DEBUG1, "rolling back to savepoint %s in logical replication parallel apply worker", spname);
1469 : :
1470 : : /*
1471 : : * Search the subxactlist, determine the offset tracked for the
1472 : : * subxact, and truncate the list.
1473 : : *
1474 : : * Note that for an empty sub-transaction we won't find the subxid
1475 : : * here.
1476 : : */
1477 [ + + ]: 12 : for (i = list_length(subxactlist) - 1; i >= 0; i--)
1478 : : {
1479 : 11 : TransactionId xid_tmp = lfirst_xid(list_nth_cell(subxactlist, i));
1480 : :
1481 [ + + ]: 11 : if (xid_tmp == subxid)
1482 : : {
1483 : 9 : RollbackToSavepoint(spname);
1484 : 9 : CommitTransactionCommand();
1485 : 9 : subxactlist = list_truncate(subxactlist, i);
1486 : 9 : break;
1487 : : }
1488 : : }
1489 : : }
1490 : 12 : }
1491 : :
1492 : : /*
1493 : : * Set the fileset state for a particular parallel apply worker. The fileset
1494 : : * will be set once the leader worker serialized all changes to the file
1495 : : * so that it can be used by parallel apply worker.
1496 : : */
1497 : : void
1498 : 16 : pa_set_fileset_state(ParallelApplyWorkerShared *wshared,
1499 : : PartialFileSetState fileset_state)
1500 : : {
1501 [ - + ]: 16 : SpinLockAcquire(&wshared->mutex);
1502 : 16 : wshared->fileset_state = fileset_state;
1503 : :
1504 [ + + ]: 16 : if (fileset_state == FS_SERIALIZE_DONE)
1505 : : {
1506 [ - + ]: 4 : Assert(am_leader_apply_worker());
1507 [ - + ]: 4 : Assert(MyLogicalRepWorker->stream_fileset);
1508 : 4 : wshared->fileset = *MyLogicalRepWorker->stream_fileset;
1509 : : }
1510 : :
1511 : 16 : SpinLockRelease(&wshared->mutex);
1512 : 16 : }
1513 : :
1514 : : /*
1515 : : * Get the fileset state for the current parallel apply worker.
1516 : : */
1517 : : static PartialFileSetState
1518 : 79 : pa_get_fileset_state(void)
1519 : : {
1520 : : PartialFileSetState fileset_state;
1521 : :
1522 [ - + ]: 79 : Assert(am_parallel_apply_worker());
1523 : :
1524 [ - + ]: 79 : SpinLockAcquire(&MyParallelShared->mutex);
1525 : 79 : fileset_state = MyParallelShared->fileset_state;
1526 : 79 : SpinLockRelease(&MyParallelShared->mutex);
1527 : :
1528 : 79 : return fileset_state;
1529 : : }
1530 : :
1531 : : /*
1532 : : * Helper functions to acquire and release a lock for each stream block.
1533 : : *
1534 : : * Set locktag_field4 to PARALLEL_APPLY_LOCK_STREAM to indicate that it's a
1535 : : * stream lock.
1536 : : *
1537 : : * Refer to the comments atop this file to see how the stream lock is used.
1538 : : */
1539 : : void
1540 : 311 : pa_lock_stream(TransactionId xid, LOCKMODE lockmode)
1541 : : {
1542 : 311 : LockApplyTransactionForSession(MyLogicalRepWorker->subid, xid,
1543 : : PARALLEL_APPLY_LOCK_STREAM, lockmode);
1544 : 309 : }
1545 : :
1546 : : void
1547 : 307 : pa_unlock_stream(TransactionId xid, LOCKMODE lockmode)
1548 : : {
1549 : 307 : UnlockApplyTransactionForSession(MyLogicalRepWorker->subid, xid,
1550 : : PARALLEL_APPLY_LOCK_STREAM, lockmode);
1551 : 307 : }
1552 : :
1553 : : /*
1554 : : * Helper functions to acquire and release a lock for each local transaction
1555 : : * apply.
1556 : : *
1557 : : * Set locktag_field4 to PARALLEL_APPLY_LOCK_XACT to indicate that it's a
1558 : : * transaction lock.
1559 : : *
1560 : : * Note that all the callers must pass a remote transaction ID instead of a
1561 : : * local transaction ID as xid. This is because the local transaction ID will
1562 : : * only be assigned while applying the first change in the parallel apply but
1563 : : * it's possible that the first change in the parallel apply worker is blocked
1564 : : * by a concurrently executing transaction in another parallel apply worker. We
1565 : : * can only communicate the local transaction id to the leader after applying
1566 : : * the first change so it won't be able to wait after sending the xact finish
1567 : : * command using this lock.
1568 : : *
1569 : : * Refer to the comments atop this file to see how the transaction lock is
1570 : : * used.
1571 : : */
1572 : : void
1573 : 60 : pa_lock_transaction(TransactionId xid, LOCKMODE lockmode)
1574 : : {
1575 : 60 : LockApplyTransactionForSession(MyLogicalRepWorker->subid, xid,
1576 : : PARALLEL_APPLY_LOCK_XACT, lockmode);
1577 : 59 : }
1578 : :
1579 : : void
1580 : 56 : pa_unlock_transaction(TransactionId xid, LOCKMODE lockmode)
1581 : : {
1582 : 56 : UnlockApplyTransactionForSession(MyLogicalRepWorker->subid, xid,
1583 : : PARALLEL_APPLY_LOCK_XACT, lockmode);
1584 : 56 : }
1585 : :
1586 : : /*
1587 : : * Decrement the number of pending streaming blocks and wait on the stream lock
1588 : : * if there is no pending block available.
1589 : : */
1590 : : void
1591 : 280 : pa_decr_and_wait_stream_block(void)
1592 : : {
1593 [ - + ]: 280 : Assert(am_parallel_apply_worker());
1594 : :
1595 : : /*
1596 : : * It is only possible to not have any pending stream chunks when we are
1597 : : * applying spooled messages.
1598 : : */
1599 [ + + ]: 280 : if (pg_atomic_read_u32(&MyParallelShared->pending_stream_count) == 0)
1600 : : {
1601 [ + - ]: 16 : if (pa_has_spooled_message_pending())
1602 : 16 : return;
1603 : :
461 akapila@postgresql.o 1604 [ # # ]:UBC 0 : elog(ERROR, "invalid pending streaming chunk 0");
1605 : : }
1606 : :
461 akapila@postgresql.o 1607 [ + + ]:CBC 264 : if (pg_atomic_sub_fetch_u32(&MyParallelShared->pending_stream_count, 1) == 0)
1608 : : {
1609 : 32 : pa_lock_stream(MyParallelShared->xid, AccessShareLock);
1610 : 30 : pa_unlock_stream(MyParallelShared->xid, AccessShareLock);
1611 : : }
1612 : : }
1613 : :
1614 : : /*
1615 : : * Finish processing the streaming transaction in the leader apply worker.
1616 : : */
1617 : : void
1618 : 29 : pa_xact_finish(ParallelApplyWorkerInfo *winfo, XLogRecPtr remote_lsn)
1619 : : {
1620 [ - + ]: 29 : Assert(am_leader_apply_worker());
1621 : :
1622 : : /*
1623 : : * Unlock the shared object lock so that parallel apply worker can
1624 : : * continue to receive and apply changes.
1625 : : */
1626 : 29 : pa_unlock_stream(winfo->shared->xid, AccessExclusiveLock);
1627 : :
1628 : : /*
1629 : : * Wait for that worker to finish. This is necessary to maintain commit
1630 : : * order which avoids failures due to transaction dependencies and
1631 : : * deadlocks.
1632 : : */
1633 : 29 : pa_wait_for_xact_finish(winfo);
1634 : :
1635 [ + + ]: 28 : if (!XLogRecPtrIsInvalid(remote_lsn))
1636 : 26 : store_flush_position(remote_lsn, winfo->shared->last_commit_end);
1637 : :
1638 : 28 : pa_free_worker(winfo);
1639 : 28 : }
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