From 3e2778d553448c67e956bd385c4a94039933d3c6 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Tue, 17 Nov 2020 13:48:16 -0300 Subject: [PATCH v6 2/4] relax lock level for setting statusFlags --- src/backend/commands/vacuum.c | 2 +- src/backend/replication/logical/logical.c | 2 +- src/backend/replication/slot.c | 2 +- src/backend/storage/ipc/procarray.c | 2 ++ 4 files changed, 5 insertions(+), 3 deletions(-) diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index d89ba3031f..395e75f768 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -1741,7 +1741,7 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams *params) * MyProc->xid/xmin, otherwise GetOldestNonRemovableTransactionId() * might appear to go backwards, which is probably Not Good. */ - LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); + LWLockAcquire(ProcArrayLock, LW_SHARED); MyProc->statusFlags |= PROC_IN_VACUUM; if (params->is_wraparound) MyProc->statusFlags |= PROC_VACUUM_FOR_WRAPAROUND; diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c index f1f4df7d70..4324e32656 100644 --- a/src/backend/replication/logical/logical.c +++ b/src/backend/replication/logical/logical.c @@ -181,7 +181,7 @@ StartupDecodingContext(List *output_plugin_options, */ if (!IsTransactionOrTransactionBlock()) { - LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); + LWLockAcquire(ProcArrayLock, LW_SHARED); MyProc->statusFlags |= PROC_IN_LOGICAL_DECODING; ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags; LWLockRelease(ProcArrayLock); diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c index 5ed955ba0b..9c7cf13d4d 100644 --- a/src/backend/replication/slot.c +++ b/src/backend/replication/slot.c @@ -527,7 +527,7 @@ ReplicationSlotRelease(void) MyReplicationSlot = NULL; /* might not have been set when we've been a plain slot */ - LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); + LWLockAcquire(ProcArrayLock, LW_SHARED); MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING; ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags; LWLockRelease(ProcArrayLock); diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index e2cb6e990d..ebe91907d6 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -662,6 +662,8 @@ ProcArrayEndTransaction(PGPROC *proc, TransactionId latestXid) /* avoid unnecessarily dirtying shared cachelines */ if (proc->statusFlags & PROC_VACUUM_STATE_MASK) { + /* Only safe to change my own flags with only share lock */ + Assert(proc == MyProc); Assert(!LWLockHeldByMe(ProcArrayLock)); LWLockAcquire(ProcArrayLock, LW_SHARED); Assert(proc->statusFlags == ProcGlobal->statusFlags[proc->pgxactoff]); -- 2.20.1