From 750dcf10d734bc54de7de7473b8abec065a75e9d Mon Sep 17 00:00:00 2001 From: Hayato Kuroda Date: Mon, 1 Dec 2025 16:28:38 +0900 Subject: [PATCH v13 2/9] Introduce a shared hash table to store parallelized transactions This hash table is used for ensuring that parallel workers wait until dependent transactions are committed. The shared hash table contains transaction IDs that the leader allocated to parallel workers. The hash entries are inserted with a remote XID when the leader bypasses remote transactions to parallel apply workers. Entries are deleted when parallel workers are committed to corresponding transactions. When the parallel worker tries to wait for other transactions, it checks the hash table for the remote XIDs. The process can go ahead only when entries are removed from the hash. Author: Zhijie Hou Author: Hayato Kuroda --- .../replication/logical/applyparallelworker.c | 100 +++++++++++++++++- .../utils/activity/wait_event_names.txt | 1 + src/include/replication/worker_internal.h | 9 ++ src/include/storage/lwlocklist.h | 1 + src/tools/pgindent/typedefs.list | 1 + 5 files changed, 111 insertions(+), 1 deletion(-) diff --git a/src/backend/replication/logical/applyparallelworker.c b/src/backend/replication/logical/applyparallelworker.c index 2432bb44655..2b34e31f86c 100644 --- a/src/backend/replication/logical/applyparallelworker.c +++ b/src/backend/replication/logical/applyparallelworker.c @@ -221,12 +221,35 @@ typedef struct ParallelApplyWorkerEntry ParallelApplyWorkerInfo *winfo; } ParallelApplyWorkerEntry; +/* An entry in the parallelized_txns shared hash table */ +typedef struct ParallelizedTxnEntry +{ + TransactionId xid; /* Hash key */ +} ParallelizedTxnEntry; + /* * A hash table used to cache the state of streaming transactions being applied * by the parallel apply workers. */ static HTAB *ParallelApplyTxnHash = NULL; +/* + * A hash table used to track the parallelized transactions that could be + * depended on by other transactions. + */ +static dsa_area *parallel_apply_dsa_area = NULL; +static dshash_table *parallelized_txns = NULL; + +/* parameters for the parallelized_txns shared hash table */ +static const dshash_parameters dsh_params = { + sizeof(TransactionId), + sizeof(ParallelizedTxnEntry), + dshash_memcmp, + dshash_memhash, + dshash_memcpy, + LWTRANCHE_PARALLEL_APPLY_DSA +}; + /* * A list (pool) of active parallel apply workers. The information for * the new worker is added to the list after successfully launching it. The @@ -260,6 +283,8 @@ static List *subxactlist = NIL; static void pa_free_worker_info(ParallelApplyWorkerInfo *winfo); static ParallelTransState pa_get_xact_state(ParallelApplyWorkerShared *wshared); static PartialFileSetState pa_get_fileset_state(void); +static void pa_attach_parallelized_txn_hash(dsa_handle *pa_dsa_handle, + dshash_table_handle *pa_dshash_handle); /* * Returns true if it is OK to start a parallel apply worker, false otherwise. @@ -337,6 +362,15 @@ pa_setup_dsm(ParallelApplyWorkerInfo *winfo) shm_mq *mq; Size queue_size = DSM_QUEUE_SIZE; Size error_queue_size = DSM_ERROR_QUEUE_SIZE; + dsa_handle parallel_apply_dsa_handle; + dshash_table_handle parallelized_txns_handle; + + pa_attach_parallelized_txn_hash(¶llel_apply_dsa_handle, + ¶llelized_txns_handle); + + if (parallel_apply_dsa_handle == DSA_HANDLE_INVALID || + parallelized_txns_handle == DSHASH_HANDLE_INVALID) + return false; /* * Estimate how much shared memory we need. @@ -372,6 +406,8 @@ pa_setup_dsm(ParallelApplyWorkerInfo *winfo) pg_atomic_init_u32(&(shared->pending_stream_count), 0); shared->last_commit_end = InvalidXLogRecPtr; shared->fileset_state = FS_EMPTY; + shared->parallel_apply_dsa_handle = parallel_apply_dsa_handle; + shared->parallelized_txns_handle = parallelized_txns_handle; shm_toc_insert(toc, PARALLEL_APPLY_KEY_SHARED, shared); @@ -945,6 +981,8 @@ ParallelApplyWorkerMain(Datum main_arg) shm_mq *mq; shm_mq_handle *mqh; shm_mq_handle *error_mqh; + dsa_handle pa_dsa_handle; + dshash_table_handle pa_dshash_handle; ReplOriginId originid; int worker_slot = DatumGetInt32(main_arg); char originname[NAMEDATALEN]; @@ -1031,6 +1069,8 @@ ParallelApplyWorkerMain(Datum main_arg) InitializingApplyWorker = false; + pa_attach_parallelized_txn_hash(&pa_dsa_handle, &pa_dshash_handle); + /* Setup replication origin tracking. */ StartTransactionCommand(); ReplicationOriginNameForLogicalRep(MySubscription->oid, InvalidOid, @@ -1726,6 +1766,51 @@ pa_xact_finish(ParallelApplyWorkerInfo *winfo, XLogRecPtr remote_lsn) pa_free_worker(winfo); } +/* + * Attach to the shared hash table for parallelized transactions. + */ +static void +pa_attach_parallelized_txn_hash(dsa_handle *pa_dsa_handle, + dshash_table_handle *pa_dshash_handle) +{ + MemoryContext oldctx; + + if (parallelized_txns) + { + Assert(parallel_apply_dsa_area); + *pa_dsa_handle = dsa_get_handle(parallel_apply_dsa_area); + *pa_dshash_handle = dshash_get_hash_table_handle(parallelized_txns); + return; + } + + /* Be sure any local memory allocated by DSA routines is persistent. */ + oldctx = MemoryContextSwitchTo(ApplyContext); + + if (am_leader_apply_worker()) + { + /* Initialize dynamic shared hash table for last-start times. */ + parallel_apply_dsa_area = dsa_create(LWTRANCHE_PARALLEL_APPLY_DSA); + dsa_pin(parallel_apply_dsa_area); + dsa_pin_mapping(parallel_apply_dsa_area); + parallelized_txns = dshash_create(parallel_apply_dsa_area, &dsh_params, NULL); + + /* Store handles in shared memory for other backends to use. */ + *pa_dsa_handle = dsa_get_handle(parallel_apply_dsa_area); + *pa_dshash_handle = dshash_get_hash_table_handle(parallelized_txns); + } + else if (am_parallel_apply_worker()) + { + /* Attach to existing dynamic shared hash table. */ + parallel_apply_dsa_area = dsa_attach(MyParallelShared->parallel_apply_dsa_handle); + dsa_pin_mapping(parallel_apply_dsa_area); + parallelized_txns = dshash_attach(parallel_apply_dsa_area, &dsh_params, + MyParallelShared->parallelized_txns_handle, + NULL); + } + + MemoryContextSwitchTo(oldctx); +} + /* * Wait for the given transaction to finish. */ @@ -1736,7 +1821,20 @@ pa_wait_for_depended_transaction(TransactionId xid) for (;;) { - /* XXX wait until given transaction is finished */ + ParallelizedTxnEntry *txn_entry; + + txn_entry = dshash_find(parallelized_txns, &xid, false); + + /* The entry is removed only if the transaction is committed */ + if (txn_entry == NULL) + break; + + dshash_release_lock(parallelized_txns, txn_entry); + + pa_lock_transaction(xid, AccessShareLock); + pa_unlock_transaction(xid, AccessShareLock); + + CHECK_FOR_INTERRUPTS(); } elog(DEBUG1, "finish waiting for depended xid %u", xid); diff --git a/src/backend/utils/activity/wait_event_names.txt b/src/backend/utils/activity/wait_event_names.txt index 560659f9568..1339c33262f 100644 --- a/src/backend/utils/activity/wait_event_names.txt +++ b/src/backend/utils/activity/wait_event_names.txt @@ -417,6 +417,7 @@ XactSLRU "Waiting to access the transaction status SLRU cache." ParallelVacuumDSA "Waiting for parallel vacuum dynamic shared memory allocation." AioUringCompletion "Waiting for another process to complete IO via io_uring." ShmemIndex "Waiting to find or allocate space in shared memory." +ParallelApplyDSA "Waiting for parallel apply dynamic shared memory allocation." # No "ABI_compatibility" region here as WaitEventLWLock has its own C code. diff --git a/src/include/replication/worker_internal.h b/src/include/replication/worker_internal.h index 21562195e19..1e41430104e 100644 --- a/src/include/replication/worker_internal.h +++ b/src/include/replication/worker_internal.h @@ -15,6 +15,7 @@ #include "access/xlogdefs.h" #include "catalog/pg_subscription.h" #include "datatype/timestamp.h" +#include "lib/dshash.h" #include "miscadmin.h" #include "replication/logicalrelation.h" #include "replication/walreceiver.h" @@ -196,6 +197,14 @@ typedef struct ParallelApplyWorkerShared */ PartialFileSetState fileset_state; FileSet fileset; + + /* + * DSA handle for parallel apply workers, along with the handle for the + * shared hash table allocated under it. The hash table stores parallelized + * transaction information. + */ + dsa_handle parallel_apply_dsa_handle; + dshash_table_handle parallelized_txns_handle; } ParallelApplyWorkerShared; /* diff --git a/src/include/storage/lwlocklist.h b/src/include/storage/lwlocklist.h index d7eb648bd27..c5f2921b703 100644 --- a/src/include/storage/lwlocklist.h +++ b/src/include/storage/lwlocklist.h @@ -140,3 +140,4 @@ PG_LWLOCKTRANCHE(XACT_SLRU, XactSLRU) PG_LWLOCKTRANCHE(PARALLEL_VACUUM_DSA, ParallelVacuumDSA) PG_LWLOCKTRANCHE(AIO_URING_COMPLETION, AioUringCompletion) PG_LWLOCKTRANCHE(SHMEM_INDEX, ShmemIndex) +PG_LWLOCKTRANCHE(PARALLEL_APPLY_DSA, ParallelApplyDSA) diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 86930f93cad..5047debff7a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2150,6 +2150,7 @@ ParallelHashJoinBatch ParallelHashJoinBatchAccessor ParallelHashJoinState ParallelIndexScanDesc +ParallelizedTxnEntry ParallelSlot ParallelSlotArray ParallelSlotResultHandler -- 2.43.7