From fe483302bdd92b0aa4bcb5bdf6902272ac6411fa Mon Sep 17 00:00:00 2001 From: Zhijie Hou Date: Wed, 29 Apr 2026 16:39:27 +0800 Subject: [PATCH v18 1/7] Introduce a shared hash table to store parallelized transactions This commit introduces a shared hash table for tracking parallelized transactions. The hash table uses transaction IDs as keys; no values are stored. 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. Any worker can use this hash table to check whether a transaction is still in progress: - If an entry exists, the transaction is still in progress. - If no entry exists, the transaction has committed. Later patches will use this hash table to support dependency waiting and commit order preservation. When transaction A depends on transaction B (or must commit after B), the worker will wait for transaction B's entry to be removed before committing transaction A. Author: Zhijie Hou Author: Hayato Kuroda --- .../replication/logical/applyparallelworker.c | 90 ++++++++++++++++++- .../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, 101 insertions(+), 1 deletion(-) diff --git a/src/backend/replication/logical/applyparallelworker.c b/src/backend/replication/logical/applyparallelworker.c index e10f653fde7..50eb574a1bf 100644 --- a/src/backend/replication/logical/applyparallelworker.c +++ b/src/backend/replication/logical/applyparallelworker.c @@ -221,12 +221,38 @@ typedef struct ParallelApplyWorkerEntry ParallelApplyWorkerInfo *winfo; } ParallelApplyWorkerEntry; +/* An entry in the parallelized_txns shared hash table */ +typedef struct ParallelizedTxnEntry +{ + TransactionId xid; /* Hash key, remote transaction ID */ +} ParallelizedTxnEntry; + /* * A hash table used to cache the state of streaming transactions being applied - * by the parallel apply workers. + * by the parallel apply workers. Entries are of type ParallelApplyWorkerEntry. */ static HTAB *ParallelApplyTxnHash = NULL; +/* + * A hash table used to track the parallelized remote transactions that could be + * depended on by other transactions. Entries are of type ParallelizedTxnEntry. + * + * dshash is used to enable dynamic shared memory allocation based on the number + * of transactions being applied in parallel. + */ +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 +286,8 @@ 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 +365,15 @@ 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 +409,8 @@ 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); @@ -876,6 +915,8 @@ 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]; @@ -962,6 +1003,8 @@ 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, @@ -1656,3 +1699,48 @@ 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 parallelized transactions */ + 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); +} 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 745b7d9e969..e60e0c3d6d7 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 9f1dd55213d..28b9eaeb7ae 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