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Remove num_xloginsert_locks GUC, replace with a #define
I left the GUC in place for the beta period, so that people could experiment with different values. No-one's come up with any data that a different value would be better under some circumstances, so rather than try to document to users what the GUC, let's just hard-code the current value, 8.
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@ -90,12 +90,18 @@ int sync_method = DEFAULT_SYNC_METHOD;
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int wal_level = WAL_LEVEL_MINIMAL;
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int CommitDelay = 0; /* precommit delay in microseconds */
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int CommitSiblings = 5; /* # concurrent xacts needed to sleep */
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int num_xloginsert_locks = 8;
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#ifdef WAL_DEBUG
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bool XLOG_DEBUG = false;
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#endif
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/*
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* Number of WAL insertion locks to use. A higher value allows more insertions
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* to happen concurrently, but adds some CPU overhead to flushing the WAL,
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* which needs to iterate all the locks.
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*/
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#define NUM_XLOGINSERT_LOCKS 8
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/*
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* XLOGfileslop is the maximum number of preallocated future XLOG segments.
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* When we are done with an old XLOG segment file, we will recycle it as a
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@ -1089,9 +1095,9 @@ begin:;
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* inserter acquires an insertion lock. In addition to just indicating that
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* an insertion is in progress, the lock tells others how far the inserter
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* has progressed. There is a small fixed number of insertion locks,
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* determined by the num_xloginsert_locks GUC. When an inserter crosses a
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* page boundary, it updates the value stored in the lock to the how far it
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* has inserted, to allow the previous buffer to be flushed.
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* determined by NUM_XLOGINSERT_LOCKS. When an inserter crosses a page
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* boundary, it updates the value stored in the lock to the how far it has
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* inserted, to allow the previous buffer to be flushed.
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*
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* Holding onto an insertion lock also protects RedoRecPtr and
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* fullPageWrites from changing until the insertion is finished.
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@ -1572,7 +1578,7 @@ WALInsertLockAcquire(void)
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static int lockToTry = -1;
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if (lockToTry == -1)
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lockToTry = MyProc->pgprocno % num_xloginsert_locks;
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lockToTry = MyProc->pgprocno % NUM_XLOGINSERT_LOCKS;
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MyLockNo = lockToTry;
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/*
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@ -1592,7 +1598,7 @@ WALInsertLockAcquire(void)
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* than locks, it still helps to distribute the inserters evenly
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* across the locks.
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*/
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lockToTry = (lockToTry + 1) % num_xloginsert_locks;
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lockToTry = (lockToTry + 1) % NUM_XLOGINSERT_LOCKS;
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}
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}
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@ -1611,7 +1617,7 @@ WALInsertLockAcquireExclusive(void)
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* than any real XLogRecPtr value, to make sure that no-one blocks waiting
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* on those.
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*/
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for (i = 0; i < num_xloginsert_locks - 1; i++)
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for (i = 0; i < NUM_XLOGINSERT_LOCKS - 1; i++)
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{
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LWLockAcquireWithVar(&WALInsertLocks[i].l.lock,
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&WALInsertLocks[i].l.insertingAt,
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@ -1634,7 +1640,7 @@ WALInsertLockRelease(void)
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{
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int i;
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for (i = 0; i < num_xloginsert_locks; i++)
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for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++)
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LWLockRelease(&WALInsertLocks[i].l.lock);
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holdingAllLocks = false;
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@ -1658,8 +1664,8 @@ WALInsertLockUpdateInsertingAt(XLogRecPtr insertingAt)
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* We use the last lock to mark our actual position, see comments in
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* WALInsertLockAcquireExclusive.
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*/
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LWLockUpdateVar(&WALInsertLocks[num_xloginsert_locks - 1].l.lock,
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&WALInsertLocks[num_xloginsert_locks - 1].l.insertingAt,
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LWLockUpdateVar(&WALInsertLocks[NUM_XLOGINSERT_LOCKS - 1].l.lock,
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&WALInsertLocks[NUM_XLOGINSERT_LOCKS - 1].l.insertingAt,
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insertingAt);
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}
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else
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@ -1726,7 +1732,7 @@ WaitXLogInsertionsToFinish(XLogRecPtr upto)
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* out for any insertion that's still in progress.
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*/
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finishedUpto = reservedUpto;
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for (i = 0; i < num_xloginsert_locks; i++)
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for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++)
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{
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XLogRecPtr insertingat = InvalidXLogRecPtr;
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@ -4781,7 +4787,7 @@ XLOGShmemSize(void)
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size = sizeof(XLogCtlData);
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/* WAL insertion locks, plus alignment */
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size = add_size(size, mul_size(sizeof(WALInsertLockPadded), num_xloginsert_locks + 1));
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size = add_size(size, mul_size(sizeof(WALInsertLockPadded), NUM_XLOGINSERT_LOCKS + 1));
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/* xlblocks array */
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size = add_size(size, mul_size(sizeof(XLogRecPtr), XLOGbuffers));
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/* extra alignment padding for XLOG I/O buffers */
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@ -4840,7 +4846,7 @@ XLOGShmemInit(void)
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((uintptr_t) allocptr) %sizeof(WALInsertLockPadded);
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WALInsertLocks = XLogCtl->Insert.WALInsertLocks =
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(WALInsertLockPadded *) allocptr;
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allocptr += sizeof(WALInsertLockPadded) * num_xloginsert_locks;
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allocptr += sizeof(WALInsertLockPadded) * NUM_XLOGINSERT_LOCKS;
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XLogCtl->Insert.WALInsertLockTrancheId = LWLockNewTrancheId();
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@ -4849,7 +4855,7 @@ XLOGShmemInit(void)
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XLogCtl->Insert.WALInsertLockTranche.array_stride = sizeof(WALInsertLockPadded);
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LWLockRegisterTranche(XLogCtl->Insert.WALInsertLockTrancheId, &XLogCtl->Insert.WALInsertLockTranche);
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for (i = 0; i < num_xloginsert_locks; i++)
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for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++)
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{
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LWLockInitialize(&WALInsertLocks[i].l.lock,
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XLogCtl->Insert.WALInsertLockTrancheId);
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@ -2119,17 +2119,6 @@ static struct config_int ConfigureNamesInt[] =
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NULL, NULL, NULL
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},
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{
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{"xloginsert_locks", PGC_POSTMASTER, WAL_SETTINGS,
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gettext_noop("Sets the number of locks used for concurrent xlog insertions."),
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NULL,
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GUC_NOT_IN_SAMPLE
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},
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&num_xloginsert_locks,
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8, 1, 1000,
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NULL, NULL, NULL
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},
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{
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/* see max_connections */
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{"max_wal_senders", PGC_POSTMASTER, REPLICATION_SENDING,
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@ -192,7 +192,6 @@ extern bool EnableHotStandby;
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extern bool fullPageWrites;
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extern bool wal_log_hints;
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extern bool log_checkpoints;
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extern int num_xloginsert_locks;
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/* WAL levels */
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typedef enum WalLevel
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