Modify MoveOfflineLogs/InstallXLogFileSegment to avoid O(N^2) behavior
when recycling a large number of xlog segments during checkpoint. The former behavior searched from the same start point each time, requiring O(checkpoint_segments^2) stat() calls to relocate all the segments. Instead keep track of where we stopped last time through.
This commit is contained in:
Tom Lane
parent
348f856dc5
commit
61b861421b
@ -7,7 +7,7 @@
|
||||
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.184 2005/04/13 18:54:56 tgl Exp $
|
||||
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.185 2005/04/15 18:48:10 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
@ -444,8 +444,8 @@ static bool AdvanceXLInsertBuffer(void);
|
||||
static void XLogWrite(XLogwrtRqst WriteRqst);
|
||||
static int XLogFileInit(uint32 log, uint32 seg,
|
||||
bool *use_existent, bool use_lock);
|
||||
static bool InstallXLogFileSegment(uint32 log, uint32 seg, char *tmppath,
|
||||
bool find_free, int max_advance,
|
||||
static bool InstallXLogFileSegment(uint32 *log, uint32 *seg, char *tmppath,
|
||||
bool find_free, int *max_advance,
|
||||
bool use_lock);
|
||||
static int XLogFileOpen(uint32 log, uint32 seg);
|
||||
static int XLogFileRead(uint32 log, uint32 seg, int emode);
|
||||
@ -1509,6 +1509,9 @@ XLogFileInit(uint32 log, uint32 seg,
|
||||
char path[MAXPGPATH];
|
||||
char tmppath[MAXPGPATH];
|
||||
char zbuffer[BLCKSZ];
|
||||
uint32 installed_log;
|
||||
uint32 installed_seg;
|
||||
int max_advance;
|
||||
int fd;
|
||||
int nbytes;
|
||||
|
||||
@ -1601,8 +1604,11 @@ XLogFileInit(uint32 log, uint32 seg,
|
||||
* else has created the file while we were filling ours: if so, use
|
||||
* ours to pre-create a future log segment.
|
||||
*/
|
||||
if (!InstallXLogFileSegment(log, seg, tmppath,
|
||||
*use_existent, XLOGfileslop,
|
||||
installed_log = log;
|
||||
installed_seg = seg;
|
||||
max_advance = XLOGfileslop;
|
||||
if (!InstallXLogFileSegment(&installed_log, &installed_seg, tmppath,
|
||||
*use_existent, &max_advance,
|
||||
use_lock))
|
||||
{
|
||||
/* No need for any more future segments... */
|
||||
@ -1722,7 +1728,7 @@ XLogFileCopy(uint32 log, uint32 seg,
|
||||
/*
|
||||
* Now move the segment into place with its final name.
|
||||
*/
|
||||
if (!InstallXLogFileSegment(log, seg, tmppath, false, 0, false))
|
||||
if (!InstallXLogFileSegment(&log, &seg, tmppath, false, NULL, false))
|
||||
elog(PANIC, "InstallXLogFileSegment should not have failed");
|
||||
}
|
||||
|
||||
@ -1732,7 +1738,9 @@ XLogFileCopy(uint32 log, uint32 seg,
|
||||
* This is used both to install a newly-created segment (which has a temp
|
||||
* filename while it's being created) and to recycle an old segment.
|
||||
*
|
||||
* log, seg: identify segment to install as (or first possible target).
|
||||
* *log, *seg: identify segment to install as (or first possible target).
|
||||
* When find_free is TRUE, these are modified on return to indicate the
|
||||
* actual installation location or last segment searched.
|
||||
*
|
||||
* tmppath: initial name of file to install. It will be renamed into place.
|
||||
*
|
||||
@ -1740,9 +1748,10 @@ XLogFileCopy(uint32 log, uint32 seg,
|
||||
* number at or after the passed numbers. If FALSE, install the new segment
|
||||
* exactly where specified, deleting any existing segment file there.
|
||||
*
|
||||
* max_advance: maximum number of log/seg slots to advance past the starting
|
||||
* point. Fail if no free slot is found in this range. (Irrelevant if
|
||||
* find_free is FALSE.)
|
||||
* *max_advance: maximum number of log/seg slots to advance past the starting
|
||||
* point. Fail if no free slot is found in this range. On return, reduced
|
||||
* by the number of slots skipped over. (Irrelevant, and may be NULL,
|
||||
* when find_free is FALSE.)
|
||||
*
|
||||
* use_lock: if TRUE, acquire ControlFileLock while moving file into
|
||||
* place. This should be TRUE except during bootstrap log creation. The
|
||||
@ -1752,14 +1761,14 @@ XLogFileCopy(uint32 log, uint32 seg,
|
||||
* exceeding max_advance limit. (Any other kind of failure causes ereport().)
|
||||
*/
|
||||
static bool
|
||||
InstallXLogFileSegment(uint32 log, uint32 seg, char *tmppath,
|
||||
bool find_free, int max_advance,
|
||||
InstallXLogFileSegment(uint32 *log, uint32 *seg, char *tmppath,
|
||||
bool find_free, int *max_advance,
|
||||
bool use_lock)
|
||||
{
|
||||
char path[MAXPGPATH];
|
||||
struct stat stat_buf;
|
||||
|
||||
XLogFilePath(path, ThisTimeLineID, log, seg);
|
||||
XLogFilePath(path, ThisTimeLineID, *log, *seg);
|
||||
|
||||
/*
|
||||
* We want to be sure that only one process does this at a time.
|
||||
@ -1777,15 +1786,16 @@ InstallXLogFileSegment(uint32 log, uint32 seg, char *tmppath,
|
||||
/* Find a free slot to put it in */
|
||||
while (stat(path, &stat_buf) == 0)
|
||||
{
|
||||
if (--max_advance < 0)
|
||||
if (*max_advance <= 0)
|
||||
{
|
||||
/* Failed to find a free slot within specified range */
|
||||
if (use_lock)
|
||||
LWLockRelease(ControlFileLock);
|
||||
return false;
|
||||
}
|
||||
NextLogSeg(log, seg);
|
||||
XLogFilePath(path, ThisTimeLineID, log, seg);
|
||||
NextLogSeg(*log, *seg);
|
||||
(*max_advance)--;
|
||||
XLogFilePath(path, ThisTimeLineID, *log, *seg);
|
||||
}
|
||||
}
|
||||
|
||||
@ -1799,14 +1809,14 @@ InstallXLogFileSegment(uint32 log, uint32 seg, char *tmppath,
|
||||
ereport(PANIC,
|
||||
(errcode_for_file_access(),
|
||||
errmsg("could not link file \"%s\" to \"%s\" (initialization of log file %u, segment %u): %m",
|
||||
tmppath, path, log, seg)));
|
||||
tmppath, path, *log, *seg)));
|
||||
unlink(tmppath);
|
||||
#else
|
||||
if (rename(tmppath, path) < 0)
|
||||
ereport(PANIC,
|
||||
(errcode_for_file_access(),
|
||||
errmsg("could not rename file \"%s\" to \"%s\" (initialization of log file %u, segment %u): %m",
|
||||
tmppath, path, log, seg)));
|
||||
tmppath, path, *log, *seg)));
|
||||
#endif
|
||||
|
||||
if (use_lock)
|
||||
@ -2129,6 +2139,7 @@ MoveOfflineLogs(uint32 log, uint32 seg, XLogRecPtr endptr,
|
||||
{
|
||||
uint32 endlogId;
|
||||
uint32 endlogSeg;
|
||||
int max_advance;
|
||||
DIR *xldir;
|
||||
struct dirent *xlde;
|
||||
char lastoff[MAXFNAMELEN];
|
||||
@ -2137,7 +2148,12 @@ MoveOfflineLogs(uint32 log, uint32 seg, XLogRecPtr endptr,
|
||||
*nsegsremoved = 0;
|
||||
*nsegsrecycled = 0;
|
||||
|
||||
/*
|
||||
* Initialize info about where to try to recycle to. We allow recycling
|
||||
* segments up to XLOGfileslop segments beyond the current XLOG location.
|
||||
*/
|
||||
XLByteToPrevSeg(endptr, endlogId, endlogSeg);
|
||||
max_advance = XLOGfileslop;
|
||||
|
||||
xldir = AllocateDir(XLogDir);
|
||||
if (xldir == NULL)
|
||||
@ -2179,12 +2195,10 @@ MoveOfflineLogs(uint32 log, uint32 seg, XLogRecPtr endptr,
|
||||
|
||||
/*
|
||||
* Before deleting the file, see if it can be recycled as
|
||||
* a future log segment. We allow recycling segments up
|
||||
* to XLOGfileslop segments beyond the current XLOG
|
||||
* location.
|
||||
* a future log segment.
|
||||
*/
|
||||
if (InstallXLogFileSegment(endlogId, endlogSeg, path,
|
||||
true, XLOGfileslop,
|
||||
if (InstallXLogFileSegment(&endlogId, &endlogSeg, path,
|
||||
true, &max_advance,
|
||||
true))
|
||||
{
|
||||
ereport(DEBUG2,
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user