From 4d5c56ea1807bf4d5c5c47fc52c09bcf51fafacb Mon Sep 17 00:00:00 2001 From: heikki Date: Thu, 25 Jun 2009 21:36:00 +0000 Subject: [PATCH] Fix some serious bugs in archive recovery, now that bgwriter is active during it: When bgwriter is active, the startup process can't perform mdsync() correctly because it won't see the fsync requests accumulated in bgwriter's private pendingOpsTable. Therefore make bgwriter responsible for the end-of-recovery checkpoint as well, when it's active. When bgwriter is active (= archive recovery), the startup process must not accumulate fsync requests to its own pendingOpsTable, since bgwriter won't see them there when it performs restartpoints. Make startup process drop its pendingOpsTable when bgwriter is launched to avoid that. Update minimum recovery point one last time when leaving archive recovery. It won't be updated by the end-of-recovery checkpoint because XLogFlush() sees us as out of recovery already. This fixes bug #4879 reported by Fujii Masao. --- src/backend/access/transam/xlog.c | 99 ++++++++++++++++++++++++++------------- src/backend/postmaster/bgwriter.c | 11 ++++- src/backend/storage/smgr/md.c | 15 ++++++ src/include/access/xlog.h | 2 + src/include/storage/smgr.h | 1 + 5 files changed, 95 insertions(+), 33 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 4fd9d418e5..d6f63c75a5 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -4912,6 +4912,7 @@ exitArchiveRecovery(TimeLineID endTLI, uint32 endLogId, uint32 endLogSeg) { char recoveryPath[MAXPGPATH]; char xlogpath[MAXPGPATH]; + XLogRecPtr InvalidXLogRecPtr = {0, 0}; /* * We are no longer in archive recovery state. @@ -4919,6 +4920,11 @@ exitArchiveRecovery(TimeLineID endTLI, uint32 endLogId, uint32 endLogSeg) InArchiveRecovery = false; /* + * Update min recovery point one last time. + */ + UpdateMinRecoveryPoint(InvalidXLogRecPtr, true); + + /* * We should have the ending log segment currently open. Verify, and then * close it (to avoid problems on Windows with trying to rename or delete * an open file). @@ -5156,6 +5162,7 @@ StartupXLOG(void) XLogRecord *record; uint32 freespace; TransactionId oldestActiveXID; + bool bgwriterLaunched = false; XLogCtl->SharedRecoveryInProgress = true; @@ -5472,7 +5479,11 @@ StartupXLOG(void) * process in addition to postmaster! */ if (InArchiveRecovery && IsUnderPostmaster) + { + SetForwardFsyncRequests(); SendPostmasterSignal(PMSIGNAL_RECOVERY_STARTED); + bgwriterLaunched = true; + } /* * main redo apply loop @@ -5709,12 +5720,6 @@ StartupXLOG(void) /* Pre-scan prepared transactions to find out the range of XIDs present */ oldestActiveXID = PrescanPreparedTransactions(); - /* - * Allow writing WAL for us, so that we can create a checkpoint record. - * But not yet for other backends! - */ - LocalRecoveryInProgress = false; - if (InRecovery) { int rmid; @@ -5743,7 +5748,12 @@ StartupXLOG(void) * the rule that TLI only changes in shutdown checkpoints, which * allows some extra error checking in xlog_redo. */ - CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE); + if (bgwriterLaunched) + RequestCheckpoint(CHECKPOINT_END_OF_RECOVERY | + CHECKPOINT_IMMEDIATE | + CHECKPOINT_WAIT); + else + CreateCheckPoint(CHECKPOINT_END_OF_RECOVERY | CHECKPOINT_IMMEDIATE); /* * And finally, execute the recovery_end_command, if any. @@ -5806,7 +5816,7 @@ StartupXLOG(void) } /* - * All done. Allow others to write WAL. + * All done. Allow backends to write WAL. */ XLogCtl->SharedRecoveryInProgress = false; } @@ -6123,12 +6133,13 @@ LogCheckpointStart(int flags, bool restartpoint) * the main message, but what about all the flags? */ if (restartpoint) - msg = "restartpoint starting:%s%s%s%s%s%s"; + msg = "restartpoint starting:%s%s%s%s%s%s%s"; else - msg = "checkpoint starting:%s%s%s%s%s%s"; + msg = "checkpoint starting:%s%s%s%s%s%s%s"; elog(LOG, msg, (flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "", + (flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "", (flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "", (flags & CHECKPOINT_FORCE) ? " force" : "", (flags & CHECKPOINT_WAIT) ? " wait" : "", @@ -6190,10 +6201,12 @@ LogCheckpointEnd(bool restartpoint) * * flags is a bitwise OR of the following: * CHECKPOINT_IS_SHUTDOWN: checkpoint is for database shutdown. + * CHECKPOINT_END_OF_RECOVERY: checkpoint is for end of WAL recovery. * CHECKPOINT_IMMEDIATE: finish the checkpoint ASAP, * ignoring checkpoint_completion_target parameter. * CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occured - * since the last one (implied by CHECKPOINT_IS_SHUTDOWN). + * since the last one (implied by CHECKPOINT_IS_SHUTDOWN and + * CHECKPOINT_END_OF_RECOVERY). * * Note: flags contains other bits, of interest here only for logging purposes. * In particular note that this routine is synchronous and does not pay @@ -6202,7 +6215,7 @@ LogCheckpointEnd(bool restartpoint) void CreateCheckPoint(int flags) { - bool shutdown = (flags & CHECKPOINT_IS_SHUTDOWN) != 0; + bool shutdown; CheckPoint checkPoint; XLogRecPtr recptr; XLogCtlInsert *Insert = &XLogCtl->Insert; @@ -6212,36 +6225,54 @@ CreateCheckPoint(int flags) uint32 _logSeg; TransactionId *inCommitXids; int nInCommit; + bool OldInRecovery = InRecovery; - /* shouldn't happen */ - if (RecoveryInProgress()) - elog(ERROR, "can't create a checkpoint during recovery"); + /* + * An end-of-recovery checkpoint is really a shutdown checkpoint, just + * issued at a different time. + */ + if (flags & ((CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY) != 0)) + shutdown = true; + else + shutdown = false; /* - * Acquire CheckpointLock to ensure only one checkpoint happens at a time. - * During normal operation, bgwriter is the only process that creates - * checkpoints, but at the end of archive recovery, the bgwriter can be - * busy creating a restartpoint while the startup process tries to perform - * the startup checkpoint. + * A startup checkpoint is created before anyone else is allowed to + * write WAL. To allow us to write the checkpoint record, set + * LocalRecoveryInProgress to false. This lets us write WAL, but others + * are still not allowed to do so. */ - if (!LWLockConditionalAcquire(CheckpointLock, LW_EXCLUSIVE)) + if (flags & CHECKPOINT_END_OF_RECOVERY) { - Assert(InRecovery); + Assert(RecoveryInProgress()); + LocalRecoveryInProgress = false; + InitXLOGAccess(); /* - * A restartpoint is in progress. Wait until it finishes. This can - * cause an extra restartpoint to be performed, but that's OK because - * we're just about to perform a checkpoint anyway. Flushing the - * buffers in this restartpoint can take some time, but that time is - * saved from the upcoming checkpoint so the net effect is zero. + * Before 8.4, end-of-recovery checkpoints were always performed by + * the startup process, and InRecovery was set true. InRecovery is not + * normally set in bgwriter, but we set it here temporarily to avoid + * confusing old code in the end-of-recovery checkpoint code path that + * rely on it. */ - ereport(DEBUG2, (errmsg("hurrying in-progress restartpoint"))); - RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_WAIT); - - LWLockAcquire(CheckpointLock, LW_EXCLUSIVE); + InRecovery = true; + } + else + { + /* shouldn't happen */ + if (RecoveryInProgress()) + elog(ERROR, "can't create a checkpoint during recovery"); } /* + * Acquire CheckpointLock to ensure only one checkpoint happens at a time. + * (This is just pro forma, since in the present system structure there is + * only one process that is allowed to issue checkpoints at any given + * time.) + */ + LWLockAcquire(CheckpointLock, LW_EXCLUSIVE); + + /* * Prepare to accumulate statistics. * * Note: because it is possible for log_checkpoints to change while a @@ -6298,7 +6329,8 @@ CreateCheckPoint(int flags) * the end of the last checkpoint record, and its redo pointer must point * to itself. */ - if ((flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_FORCE)) == 0) + if ((flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY | + CHECKPOINT_FORCE)) == 0) { XLogRecPtr curInsert; @@ -6542,6 +6574,9 @@ CreateCheckPoint(int flags) CheckpointStats.ckpt_segs_recycled); LWLockRelease(CheckpointLock); + + /* Restore old value */ + InRecovery = OldInRecovery; } /* diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c index 55dff57298..1647e3ce29 100644 --- a/src/backend/postmaster/bgwriter.c +++ b/src/backend/postmaster/bgwriter.c @@ -449,6 +449,13 @@ BackgroundWriterMain(void) SpinLockRelease(&bgs->ckpt_lck); /* + * The end-of-recovery checkpoint is a real checkpoint that's + * performed while we're still in recovery. + */ + if (flags & CHECKPOINT_END_OF_RECOVERY) + do_restartpoint = false; + + /* * We will warn if (a) too soon since last checkpoint (whatever * caused it) and (b) somebody set the CHECKPOINT_CAUSE_XLOG flag * since the last checkpoint start. Note in particular that this @@ -895,10 +902,12 @@ BgWriterShmemInit(void) * * flags is a bitwise OR of the following: * CHECKPOINT_IS_SHUTDOWN: checkpoint is for database shutdown. + * CHECKPOINT_END_OF_RECOVERY: checkpoint is to finish WAL recovery. * CHECKPOINT_IMMEDIATE: finish the checkpoint ASAP, * ignoring checkpoint_completion_target parameter. * CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occured - * since the last one (implied by CHECKPOINT_IS_SHUTDOWN). + * since the last one (implied by CHECKPOINT_IS_SHUTDOWN and + * CHECKPOINT_END_OF_RECOVERY). * CHECKPOINT_WAIT: wait for completion before returning (otherwise, * just signal bgwriter to do it, and return). * CHECKPOINT_CAUSE_XLOG: checkpoint is requested due to xlog filling. diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c index d42e86a342..b01b2abe6a 100644 --- a/src/backend/storage/smgr/md.c +++ b/src/backend/storage/smgr/md.c @@ -204,6 +204,21 @@ mdinit(void) } /* + * In archive recovery, we rely on bgwriter to do fsyncs(), but we don't + * know that we do archive recovery at process startup when pendingOpsTable + * has already been created. Calling this function drops pendingOpsTable + * and causes any subsequent requests to be forwarded to bgwriter. + */ +void +SetForwardFsyncRequests(void) +{ + /* Perform any pending ops we may have queued up */ + if (pendingOpsTable) + mdsync(); + pendingOpsTable = NULL; +} + +/* * mdexists() -- Does the physical file exist? * * Note: this will return true for lingering files, with pending deletions diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index f8720bbc2c..a46e03b831 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -166,6 +166,8 @@ extern bool XLOG_DEBUG; /* These indicate the cause of a checkpoint request */ #define CHECKPOINT_CAUSE_XLOG 0x0010 /* XLOG consumption */ #define CHECKPOINT_CAUSE_TIME 0x0020 /* Elapsed time */ +#define CHECKPOINT_END_OF_RECOVERY 0x0040 /* Like shutdown checkpoint, but + * issued at end of WAL recovery */ /* Checkpoint statistics */ typedef struct CheckpointStatsData diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h index 7556b14ca6..fd79d7b104 100644 --- a/src/include/storage/smgr.h +++ b/src/include/storage/smgr.h @@ -109,6 +109,7 @@ extern void mdpreckpt(void); extern void mdsync(void); extern void mdpostckpt(void); +extern void SetForwardFsyncRequests(void); extern void RememberFsyncRequest(RelFileNode rnode, ForkNumber forknum, BlockNumber segno); extern void ForgetRelationFsyncRequests(RelFileNode rnode, ForkNumber forknum); -- 2.11.4.GIT