>From 54cf27b505efcf5aeeb2b78638e88fab04e66b5b Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Thu, 13 Dec 2012 20:47:57 +0100 Subject: [PATCH 11/19] wal_decoding: Add alreadyLocked parameter to GetOldestXminNoLock This is useful because it allows to compute the current OldestXmin while already holding the procarray lock which enables setting the own xmin horizon safely. --- src/backend/access/transam/xlog.c | 4 ++-- src/backend/catalog/index.c | 3 ++- src/backend/commands/analyze.c | 2 +- src/backend/commands/vacuum.c | 4 ++-- src/backend/replication/walreceiver.c | 2 +- src/backend/storage/ipc/procarray.c | 16 ++++++++-------- src/include/storage/procarray.h | 2 +- 7 files changed, 17 insertions(+), 16 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 310a654..ab7f0e4 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -6823,7 +6823,7 @@ CreateCheckPoint(int flags) * StartupSUBTRANS hasn't been called yet. */ if (!RecoveryInProgress()) - TruncateSUBTRANS(GetOldestXmin(true, false)); + TruncateSUBTRANS(GetOldestXmin(true, false, false)); /* Real work is done, but log and update stats before releasing lock. */ LogCheckpointEnd(false); @@ -7107,7 +7107,7 @@ CreateRestartPoint(int flags) * this because StartupSUBTRANS hasn't been called yet. */ if (EnableHotStandby) - TruncateSUBTRANS(GetOldestXmin(true, false)); + TruncateSUBTRANS(GetOldestXmin(true, false, false)); /* Real work is done, but log and update before releasing lock. */ LogCheckpointEnd(true); diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index a29c106..dbee4d5 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -2196,7 +2196,8 @@ IndexBuildHeapScan(Relation heapRelation, { snapshot = SnapshotAny; /* okay to ignore lazy VACUUMs here */ - OldestXmin = GetOldestXmin(heapRelation->rd_rel->relisshared, true); + OldestXmin = GetOldestXmin(heapRelation->rd_rel->relisshared, true, + false); } scan = heap_beginscan_strat(heapRelation, /* relation */ diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c index ac16284..f5a6af7 100644 --- a/src/backend/commands/analyze.c +++ b/src/backend/commands/analyze.c @@ -1077,7 +1077,7 @@ acquire_sample_rows(Relation onerel, int elevel, totalblocks = RelationGetNumberOfBlocks(onerel); /* Need a cutoff xmin for HeapTupleSatisfiesVacuum */ - OldestXmin = GetOldestXmin(onerel->rd_rel->relisshared, true); + OldestXmin = GetOldestXmin(onerel->rd_rel->relisshared, true, false); /* Prepare for sampling block numbers */ BlockSampler_Init(&bs, totalblocks, targrows); diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index 2d3170a..158d0dc 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -394,7 +394,7 @@ vacuum_set_xid_limits(int freeze_min_age, * working on a particular table at any time, and that each vacuum is * always an independent transaction. */ - *oldestXmin = GetOldestXmin(sharedRel, true); + *oldestXmin = GetOldestXmin(sharedRel, true, false); Assert(TransactionIdIsNormal(*oldestXmin)); @@ -686,7 +686,7 @@ vac_update_datfrozenxid(void) * committed pg_class entries for new tables; see AddNewRelationTuple(). * Se we cannot produce a wrong minimum by starting with this. */ - newFrozenXid = GetOldestXmin(true, true); + newFrozenXid = GetOldestXmin(true, true, false); /* * We must seqscan pg_class to find the minimum Xid, because there is no diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c index 16cf944..2b77369 100644 --- a/src/backend/replication/walreceiver.c +++ b/src/backend/replication/walreceiver.c @@ -1089,7 +1089,7 @@ XLogWalRcvSendHSFeedback(void) * Make the expensive call to get the oldest xmin once we are certain * everything else has been checked. */ - xmin = GetOldestXmin(true, false); + xmin = GetOldestXmin(true, false, false); /* * Get epoch and adjust if nextXid and oldestXmin are different sides of diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index 4308128..f59e792 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -1100,7 +1100,7 @@ TransactionIdIsActive(TransactionId xid) * GetOldestXmin() move backwards, with no consequences for data integrity. */ TransactionId -GetOldestXmin(bool allDbs, bool ignoreVacuum) +GetOldestXmin(bool allDbs, bool ignoreVacuum, bool alreadyLocked) { ProcArrayStruct *arrayP = procArray; TransactionId result; @@ -1109,7 +1109,8 @@ GetOldestXmin(bool allDbs, bool ignoreVacuum) /* Cannot look for individual databases during recovery */ Assert(allDbs || !RecoveryInProgress()); - LWLockAcquire(ProcArrayLock, LW_SHARED); + if (!alreadyLocked) + LWLockAcquire(ProcArrayLock, LW_SHARED); /* * We initialize the MIN() calculation with latestCompletedXid + 1. This @@ -1164,7 +1165,8 @@ GetOldestXmin(bool allDbs, bool ignoreVacuum) */ TransactionId kaxmin = KnownAssignedXidsGetOldestXmin(); - LWLockRelease(ProcArrayLock); + if (!alreadyLocked) + LWLockRelease(ProcArrayLock); if (TransactionIdIsNormal(kaxmin) && TransactionIdPrecedes(kaxmin, result)) @@ -1172,10 +1174,8 @@ GetOldestXmin(bool allDbs, bool ignoreVacuum) } else { - /* - * No other information needed, so release the lock immediately. - */ - LWLockRelease(ProcArrayLock); + if (!alreadyLocked) + LWLockRelease(ProcArrayLock); /* * Compute the cutoff XID by subtracting vacuum_defer_cleanup_age, @@ -1249,7 +1249,7 @@ GetMaxSnapshotSubxidCount(void) * older than this are known not running any more. * RecentGlobalXmin: the global xmin (oldest TransactionXmin across all * running transactions, except those running LAZY VACUUM). This is - * the same computation done by GetOldestXmin(true, true). + * the same computation done by GetOldestXmin(true, true, ...). * * Note: this function should probably not be called with an argument that's * not statically allocated (see xip allocation below). diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h index d5fdfea..fe0bad7 100644 --- a/src/include/storage/procarray.h +++ b/src/include/storage/procarray.h @@ -49,7 +49,7 @@ extern RunningTransactions GetRunningTransactionData(void); extern bool TransactionIdIsInProgress(TransactionId xid); extern bool TransactionIdIsActive(TransactionId xid); -extern TransactionId GetOldestXmin(bool allDbs, bool ignoreVacuum); +extern TransactionId GetOldestXmin(bool allDbs, bool ignoreVacuum, bool alreadyLocked); extern TransactionId GetOldestActiveTransactionId(void); extern VirtualTransactionId *GetVirtualXIDsDelayingChkpt(int *nvxids); -- 1.7.12.289.g0ce9864.dirty