diff options
Diffstat (limited to 'src/backend/access/transam/multixact.c')
| -rw-r--r-- | src/backend/access/transam/multixact.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index 454ca310f33..0f4cea124d7 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -1655,8 +1655,9 @@ CheckPointMultiXact(void) * Set the next-to-be-assigned MultiXactId and offset * * This is used when we can determine the correct next ID/offset exactly - * from a checkpoint record. We need no locking since it is only called - * during bootstrap and XLog replay. + * from a checkpoint record. Although this is only called during bootstrap + * and XLog replay, we take the lock in case any hot-standby backends are + * examining the values. */ void MultiXactSetNextMXact(MultiXactId nextMulti, @@ -1664,8 +1665,10 @@ MultiXactSetNextMXact(MultiXactId nextMulti, { debug_elog4(DEBUG2, "MultiXact: setting next multi to %u offset %u", nextMulti, nextMultiOffset); + LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); MultiXactState->nextMXact = nextMulti; MultiXactState->nextOffset = nextMultiOffset; + LWLockRelease(MultiXactGenLock); } /* @@ -1674,12 +1677,14 @@ MultiXactSetNextMXact(MultiXactId nextMulti, * * This is used when we can determine minimum safe values from an XLog * record (either an on-line checkpoint or an mxact creation log entry). - * We need no locking since it is only called during XLog replay. + * Although this is only called during XLog replay, we take the lock in case + * any hot-standby backends are examining the values. */ void MultiXactAdvanceNextMXact(MultiXactId minMulti, MultiXactOffset minMultiOffset) { + LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); if (MultiXactIdPrecedes(MultiXactState->nextMXact, minMulti)) { debug_elog3(DEBUG2, "MultiXact: setting next multi to %u", minMulti); @@ -1691,6 +1696,7 @@ MultiXactAdvanceNextMXact(MultiXactId minMulti, minMultiOffset); MultiXactState->nextOffset = minMultiOffset; } + LWLockRelease(MultiXactGenLock); } /* |