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Revert "Avoid creating archive status ".ready" files too early"

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This reverts commit 515e3d84a0b5 and equivalent commits in back
branches.  This solution to the problem has a number of problems, so
we'll try again with a different approach.

Per note from Andres Freund

Discussion: https://postgr.es/m/20210831042949.52eqp5xwbxgrfank@alap3.anarazel.de
This commit is contained in:
Alvaro Herrera 2021-09-04 12:14:30 -04:00
parent beb404d3b1
commit c801c3a1ff
No known key found for this signature in database
GPG Key ID: 1C20ACB9D5C564AE
4 changed files with 10 additions and 215 deletions
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216
src/backend/access/transam/xlog.c
View File

@ -703,18 +703,6 @@ typedef struct XLogCtlData
XLogRecPtr lastFpwDisableRecPtr;
slock_t info_lck; /* locks shared variables shown above */
/*
* Variables used to track segment-boundary-crossing WAL records. See
* RegisterSegmentBoundary. Protected by segtrack_lck.
*/
XLogSegNo lastNotifiedSeg;
XLogSegNo earliestSegBoundary;
XLogRecPtr earliestSegBoundaryEndPtr;
XLogSegNo latestSegBoundary;
XLogRecPtr latestSegBoundaryEndPtr;
slock_t segtrack_lck; /* locks shared variables shown above */
} XLogCtlData;
static XLogCtlData *XLogCtl = NULL;
@ -907,7 +895,6 @@ static void RemoveOldXlogFiles(XLogSegNo segno, XLogRecPtr lastredoptr, XLogRecP
static void RemoveXlogFile(const char *segname, XLogRecPtr lastredoptr, XLogRecPtr endptr);
static void UpdateLastRemovedPtr(char *filename);
static void ValidateXLOGDirectoryStructure(void);
static void RegisterSegmentBoundary(XLogSegNo seg, XLogRecPtr pos);
static void CleanupBackupHistory(void);
static void UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force);
static XLogRecord *ReadRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,
@ -1138,56 +1125,23 @@ XLogInsertRecord(XLogRecData *rdata,
END_CRIT_SECTION();
/*
* If we crossed page boundary, update LogwrtRqst.Write; if we crossed
* segment boundary, register that and wake up walwriter.
* Update shared LogwrtRqst.Write, if we crossed page boundary.
*/
if (StartPos / XLOG_BLCKSZ != EndPos / XLOG_BLCKSZ)
{
XLogSegNo StartSeg;
XLogSegNo EndSeg;
XLByteToSeg(StartPos, StartSeg, wal_segment_size);
XLByteToSeg(EndPos, EndSeg, wal_segment_size);
/*
* Register our crossing the segment boundary if that occurred.
*
* Note that we did not use XLByteToPrevSeg() for determining the
* ending segment. This is so that a record that fits perfectly into
* the end of the segment causes the latter to get marked ready for
* archival immediately.
*/
if (StartSeg != EndSeg && XLogArchivingActive())
RegisterSegmentBoundary(EndSeg, EndPos);
/*
* Advance LogwrtRqst.Write so that it includes new block(s).
*
* We do this after registering the segment boundary so that the
* comparison with the flushed pointer below can use the latest value
* known globally.
*/
SpinLockAcquire(&XLogCtl->info_lck);
/* advance global request to include new block(s) */
if (XLogCtl->LogwrtRqst.Write < EndPos)
XLogCtl->LogwrtRqst.Write = EndPos;
/* update local result copy while I have the chance */
LogwrtResult = XLogCtl->LogwrtResult;
SpinLockRelease(&XLogCtl->info_lck);
/*
* There's a chance that the record was already flushed to disk and we
* missed marking segments as ready for archive. If this happens, we
* nudge the WALWriter, which will take care of notifying segments as
* needed.
*/
if (StartSeg != EndSeg && XLogArchivingActive() &&
LogwrtResult.Flush >= EndPos && ProcGlobal->walwriterLatch)
SetLatch(ProcGlobal->walwriterLatch);
}
/*
* If this was an XLOG_SWITCH record, flush the record and the empty
* padding space that fills the rest of the segment.
* padding space that fills the rest of the segment, and perform
* end-of-segment actions (eg, notifying archiver).
*/
if (isLogSwitch)
{
@ -2430,7 +2384,6 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
/* We should always be inside a critical section here */
Assert(CritSectionCount > 0);
Assert(LWLockHeldByMe(WALWriteLock));
/*
* Update local LogwrtResult (caller probably did this already, but...)
@ -2582,12 +2535,11 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
* later. Doing it here ensures that one and only one backend will
* perform this fsync.
*
* If WAL archiving is active, we attempt to notify the archiver
* of any segments that are now ready for archival.
*
* This is also the right place to update the timer for
* archive_timeout and to signal for a checkpoint if too many
* logfile segments have been used since the last checkpoint.
* This is also the right place to notify the Archiver that the
* segment is ready to copy to archival storage, and to update the
* timer for archive_timeout, and to signal for a checkpoint if
* too many logfile segments have been used since the last
* checkpoint.
*/
if (finishing_seg)
{
@ -2599,7 +2551,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
LogwrtResult.Flush = LogwrtResult.Write; /* end of page */
if (XLogArchivingActive())
NotifySegmentsReadyForArchive(LogwrtResult.Flush);
XLogArchiveNotifySeg(openLogSegNo);
XLogCtl->lastSegSwitchTime = (pg_time_t) time(NULL);
XLogCtl->lastSegSwitchLSN = LogwrtResult.Flush;
@ -2687,9 +2639,6 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
XLogCtl->LogwrtRqst.Flush = LogwrtResult.Flush;
SpinLockRelease(&XLogCtl->info_lck);
}
if (XLogArchivingActive())
NotifySegmentsReadyForArchive(LogwrtResult.Flush);
}
/*
@ -4226,129 +4175,6 @@ ValidateXLOGDirectoryStructure(void)
}
}
/*
* RegisterSegmentBoundary
*
* WAL records that are split across a segment boundary require special
* treatment for archiving: the initial segment must not be archived until
* the end segment has been flushed, in case we crash before we have
* the chance to flush the end segment (because after recovery we would
* overwrite that WAL record with a different one, and so the file we
* archived no longer represents truth.) This also applies to streaming
* physical replication.
*
* To handle this, we keep track of the LSN of WAL records that cross
* segment boundaries. Two such are sufficient: the ones with the
* earliest and the latest end pointers we know about, since the flush
* position advances monotonically. WAL record writers register
* boundary-crossing records here, which is used by .ready file creation
* to delay until the end segment is known flushed.
*/
static void
RegisterSegmentBoundary(XLogSegNo seg, XLogRecPtr endpos)
{
XLogSegNo segno PG_USED_FOR_ASSERTS_ONLY;
/* verify caller computed segment number correctly */
AssertArg((XLByteToSeg(endpos, segno, wal_segment_size), segno == seg));
SpinLockAcquire(&XLogCtl->segtrack_lck);
/*
* If no segment boundaries are registered, store the new segment boundary
* in earliestSegBoundary. Otherwise, store the greater segment
* boundaries in latestSegBoundary.
*/
if (XLogCtl->earliestSegBoundary == MaxXLogSegNo)
{
XLogCtl->earliestSegBoundary = seg;
XLogCtl->earliestSegBoundaryEndPtr = endpos;
}
else if (seg > XLogCtl->earliestSegBoundary &&
(XLogCtl->latestSegBoundary == MaxXLogSegNo ||
seg > XLogCtl->latestSegBoundary))
{
XLogCtl->latestSegBoundary = seg;
XLogCtl->latestSegBoundaryEndPtr = endpos;
}
SpinLockRelease(&XLogCtl->segtrack_lck);
}
/*
* NotifySegmentsReadyForArchive
*
* Mark segments as ready for archival, given that it is safe to do so.
* This function is idempotent.
*/
void
NotifySegmentsReadyForArchive(XLogRecPtr flushRecPtr)
{
XLogSegNo latest_boundary_seg;
XLogSegNo last_notified;
XLogSegNo flushed_seg;
XLogSegNo seg;
bool keep_latest;
XLByteToSeg(flushRecPtr, flushed_seg, wal_segment_size);
SpinLockAcquire(&XLogCtl->segtrack_lck);
if (XLogCtl->latestSegBoundary <= flushed_seg &&
XLogCtl->latestSegBoundaryEndPtr <= flushRecPtr)
{
latest_boundary_seg = XLogCtl->latestSegBoundary;
keep_latest = false;
}
else if (XLogCtl->earliestSegBoundary <= flushed_seg &&
XLogCtl->earliestSegBoundaryEndPtr <= flushRecPtr)
{
latest_boundary_seg = XLogCtl->earliestSegBoundary;
keep_latest = true;
}
else
{
SpinLockRelease(&XLogCtl->segtrack_lck);
return;
}
last_notified = XLogCtl->lastNotifiedSeg;
/*
* Update shared memory and discard segment boundaries that are no longer
* needed.
*
* It is safe to update shared memory before we attempt to create the
* .ready files. If our calls to XLogArchiveNotifySeg() fail,
* RemoveOldXlogFiles() will retry it as needed.
*/
if (last_notified < latest_boundary_seg - 1)
XLogCtl->lastNotifiedSeg = latest_boundary_seg - 1;
if (keep_latest)
{
XLogCtl->earliestSegBoundary = XLogCtl->latestSegBoundary;
XLogCtl->earliestSegBoundaryEndPtr = XLogCtl->latestSegBoundaryEndPtr;
}
else
{
XLogCtl->earliestSegBoundary = MaxXLogSegNo;
XLogCtl->earliestSegBoundaryEndPtr = InvalidXLogRecPtr;
}
XLogCtl->latestSegBoundary = MaxXLogSegNo;
XLogCtl->latestSegBoundaryEndPtr = InvalidXLogRecPtr;
SpinLockRelease(&XLogCtl->segtrack_lck);
/*
* Notify archiver about segments that are ready for archival (by creating
* the corresponding .ready files).
*/
for (seg = last_notified + 1; seg < latest_boundary_seg; seg++)
XLogArchiveNotifySeg(seg);
}
/*
* Remove previous backup history files. This also retries creation of
* .ready files for any backup history files for which XLogArchiveNotify
@ -5266,16 +5092,8 @@ XLOGShmemInit(void)
SpinLockInit(&XLogCtl->Insert.insertpos_lck);
SpinLockInit(&XLogCtl->info_lck);
SpinLockInit(&XLogCtl->segtrack_lck);
SpinLockInit(&XLogCtl->ulsn_lck);
InitSharedLatch(&XLogCtl->recoveryWakeupLatch);
/* Initialize stuff for marking segments as ready for archival. */
XLogCtl->lastNotifiedSeg = MaxXLogSegNo;
XLogCtl->earliestSegBoundary = MaxXLogSegNo;
XLogCtl->earliestSegBoundaryEndPtr = InvalidXLogRecPtr;
XLogCtl->latestSegBoundary = MaxXLogSegNo;
XLogCtl->latestSegBoundaryEndPtr = InvalidXLogRecPtr;
}
/*
@ -7900,20 +7718,6 @@ StartupXLOG(void)
XLogCtl->LogwrtRqst.Write = EndOfLog;
XLogCtl->LogwrtRqst.Flush = EndOfLog;
/*
* Initialize XLogCtl->lastNotifiedSeg to the previous WAL file.
*/
if (XLogArchivingActive())
{
XLogSegNo EndOfLogSeg;
XLByteToSeg(EndOfLog, EndOfLogSeg, wal_segment_size);
SpinLockAcquire(&XLogCtl->segtrack_lck);
XLogCtl->lastNotifiedSeg = EndOfLogSeg - 1;
SpinLockRelease(&XLogCtl->segtrack_lck);
}
/*
* Update full_page_writes in shared memory and write an XLOG_FPW_CHANGE
* record before resource manager writes cleanup WAL records or checkpoint

7
src/backend/postmaster/walwriter.c
View File

@ -271,13 +271,6 @@ WalWriterMain(void)
proc_exit(0); /* done */
}
/*
* Notify the archiver of any WAL segments that are ready. We do this
* here to handle a race condition where WAL is flushed to disk prior
* to registering the segment boundary.
*/
NotifySegmentsReadyForArchive(GetFlushRecPtr());
/*
* Do what we're here for; then, if XLogBackgroundFlush() found useful
* work to do, reset hibernation counter.

1
src/include/access/xlog.h
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@ -289,7 +289,6 @@ extern XLogRecPtr GetFlushRecPtr(void);
extern XLogRecPtr GetLastImportantRecPtr(void);
extern void GetNextXidAndEpoch(TransactionId *xid, uint32 *epoch);
extern void RemovePromoteSignalFiles(void);
extern void NotifySegmentsReadyForArchive(XLogRecPtr flushRecPtr);
extern bool CheckPromoteSignal(void);
extern void WakeupRecovery(void);

1
src/include/access/xlogdefs.h
View File

@ -32,7 +32,6 @@ typedef uint64 XLogRecPtr;
* XLogSegNo - physical log file sequence number.
*/
typedef uint64 XLogSegNo;
#define MaxXLogSegNo ((XLogSegNo) 0xFFFFFFFFFFFFFFFF)
/*
* TimeLineID (TLI) - identifies different database histories to prevent