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Add GUC log_lock_waits to log long wait times. 

Simon Riggs
This commit is contained in:
Bruce Momjian 2007-03-03 18:46:40 +00:00
parent f52019cf80
commit e52c4a6e26
7 changed files with 122 additions and 61 deletions
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26
doc/src/sgml/config.sgml
View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.113 2007/03/02 23:37:22 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.114 2007/03/03 18:46:40 momjian Exp $ -->
<chapter Id="runtime-config">
<title>Server Configuration</title>
@ -2946,6 +2946,21 @@ SELECT * FROM parent WHERE key = 2400;
</listitem>
</varlistentry>
<varlistentry id="guc-log-lock-waits" xreflabel="log_lock_waits">
<term><varname>log_lock_waits</varname> (<type>boolean</type>)</term>
<indexterm>
<primary><varname>log_lock_waits</> configuration parameter</primary>
</indexterm>
<listitem>
<para>
Controls whether a log message is produced when a statement waits
longer than <xref linkend="guc-deadlock-timeout"> to acquire a
lock. This is useful in determining if lock waits are causing
poor performance. The default is <literal>off</>.
</para>
</listitem>
</varlistentry>
<varlistentry id="guc-log-temp-files" xreflabel="log_temp_files">
<term><varname>log_temp_files</varname> (<type>integer</type>)</term>
<indexterm>
@ -3980,17 +3995,18 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
This is the amount of time, in milliseconds, to wait on a lock
before checking to see if there is a deadlock condition. The
check for deadlock is relatively slow, so the server doesn't run
it every time it waits for a lock. We (optimistically?) assume
it every time it waits for a lock. We optimistically assume
that deadlocks are not common in production applications and
just wait on the lock for a while before starting the check for a
deadlock. Increasing this value reduces the amount of time
wasted in needless deadlock checks, but slows down reporting of
real deadlock errors. The default is one second (<literal>1s</>),
which is probably about the smallest value you would want in
practice. On a heavily loaded server you might want to raise it.
practice. Set <xref linkend="guc-log-lock-waits"> to log deadlock
checks. On a heavily loaded server you might want to raise it.
Ideally the setting should exceed your typical transaction time,
so as to improve the odds that a lock will be released before
the waiter decides to check for deadlock.
so as to improve the odds that a lock will be released before the
waiter decides to check for deadlock.
</para>
</listitem>
</varlistentry>

22
src/backend/storage/lmgr/deadlock.c
View File

@ -12,7 +12,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/deadlock.c,v 1.44 2007/01/05 22:19:38 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/deadlock.c,v 1.45 2007/03/03 18:46:40 momjian Exp $
*
* Interface:
*
@ -187,13 +187,14 @@ InitDeadLockChecking(void)
* deadlock. If resolution is impossible, return TRUE --- the caller
* is then expected to abort the given proc's transaction.
*
* Caller must already have locked all partitions of the lock tables.
* Caller must already have locked all partitions of the lock tables,
* so standard error logging/reporting code is handled by caller.
*
* On failure, deadlock details are recorded in deadlockDetails[] for
* subsequent printing by DeadLockReport(). That activity is separate
* because we don't want to do it while holding all those LWLocks.
*/
bool
DeadlockState
DeadLockCheck(PGPROC *proc)
{
int i,
@ -204,6 +205,11 @@ DeadLockCheck(PGPROC *proc)
nPossibleConstraints = 0;
nWaitOrders = 0;
#ifdef LOCK_DEBUG
if (Debug_deadlocks)
DumpAllLocks();
#endif
/* Search for deadlocks and possible fixes */
if (DeadLockCheckRecurse(proc))
{
@ -217,7 +223,7 @@ DeadLockCheck(PGPROC *proc)
if (!FindLockCycle(proc, possibleConstraints, &nSoftEdges))
elog(FATAL, "deadlock seems to have disappeared");
return true; /* cannot find a non-deadlocked state */
return DS_HARD_DEADLOCK; /* cannot find a non-deadlocked state */
}
/* Apply any needed rearrangements of wait queues */
@ -249,7 +255,11 @@ DeadLockCheck(PGPROC *proc)
/* See if any waiters for the lock can be woken up now */
ProcLockWakeup(GetLocksMethodTable(lock), lock);
}
return false;
if (nWaitOrders > 0)
return DS_SOFT_DEADLOCK;
else
return DS_DEADLOCK_NOT_FOUND;
}
/*
@ -896,7 +906,7 @@ DescribeLockTag(StringInfo buf, const LOCKTAG *lock)
}
/*
* Report a detected deadlock, with available details.
* Report a detected DS_HARD_DEADLOCK, with available details.
*/
void
DeadLockReport(void)

109
src/backend/storage/lmgr/proc.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.184 2007/02/15 23:23:23 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.185 2007/03/03 18:46:40 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -48,6 +48,7 @@
/* GUC variables */
int DeadlockTimeout = 1000;
int StatementTimeout = 0;
bool log_lock_waits = false;
/* Pointer to this process's PGPROC struct, if any */
PGPROC *MyProc = NULL;
@ -979,6 +980,7 @@ static void
CheckDeadLock(void)
{
int i;
DeadlockState deadlock_state = DS_DEADLOCK_NOT_FOUND;
/*
* Acquire exclusive lock on the entire shared lock data structures. Must
@ -1004,60 +1006,77 @@ CheckDeadLock(void)
* This is quicker than checking our semaphore's state, since no kernel
* call is needed, and it is safe because we hold the lock partition lock.
*/
if (MyProc->links.prev == INVALID_OFFSET ||
MyProc->links.next == INVALID_OFFSET)
goto check_done;
#ifdef LOCK_DEBUG
if (Debug_deadlocks)
DumpAllLocks();
#endif
if (!DeadLockCheck(MyProc))
if (MyProc->links.prev != INVALID_OFFSET &&
MyProc->links.next != INVALID_OFFSET)
deadlock_state = DeadLockCheck(MyProc);
if (deadlock_state == DS_HARD_DEADLOCK)
{
/* No deadlock, so keep waiting */
goto check_done;
/*
* Oops. We have a deadlock.
*
* Get this process out of wait state. (Note: we could do this more
* efficiently by relying on lockAwaited, but use this coding to preserve
* the flexibility to kill some other transaction than the one detecting
* the deadlock.)
*
* RemoveFromWaitQueue sets MyProc->waitStatus to STATUS_ERROR, so
* ProcSleep will report an error after we return from the signal handler.
*/
Assert(MyProc->waitLock != NULL);
RemoveFromWaitQueue(MyProc, LockTagHashCode(&(MyProc->waitLock->tag)));
/*
* Unlock my semaphore so that the interrupted ProcSleep() call can
* finish.
*/
PGSemaphoreUnlock(&MyProc->sem);
/*
* We're done here. Transaction abort caused by the error that ProcSleep
* will raise will cause any other locks we hold to be released, thus
* allowing other processes to wake up; we don't need to do that here.
* NOTE: an exception is that releasing locks we hold doesn't consider the
* possibility of waiters that were blocked behind us on the lock we just
* failed to get, and might now be wakable because we're not in front of
* them anymore. However, RemoveFromWaitQueue took care of waking up any
* such processes.
*/
}
/*
* Oops. We have a deadlock.
*
* Get this process out of wait state. (Note: we could do this more
* efficiently by relying on lockAwaited, but use this coding to preserve
* the flexibility to kill some other transaction than the one detecting
* the deadlock.)
*
* RemoveFromWaitQueue sets MyProc->waitStatus to STATUS_ERROR, so
* ProcSleep will report an error after we return from the signal handler.
*/
Assert(MyProc->waitLock != NULL);
RemoveFromWaitQueue(MyProc, LockTagHashCode(&(MyProc->waitLock->tag)));
/*
* Unlock my semaphore so that the interrupted ProcSleep() call can
* finish.
*/
PGSemaphoreUnlock(&MyProc->sem);
/*
* We're done here. Transaction abort caused by the error that ProcSleep
* will raise will cause any other locks we hold to be released, thus
* allowing other processes to wake up; we don't need to do that here.
* NOTE: an exception is that releasing locks we hold doesn't consider the
* possibility of waiters that were blocked behind us on the lock we just
* failed to get, and might now be wakable because we're not in front of
* them anymore. However, RemoveFromWaitQueue took care of waking up any
* such processes.
*/
/*
* Release locks acquired at head of routine. Order is not critical, so
* do it back-to-front to avoid waking another CheckDeadLock instance
* before it can get all the locks.
*/
check_done:
for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
LWLockRelease(FirstLockMgrLock + i);
/*
* Issue any log messages requested.
*
* Deadlock ERROR messages are issued as part of transaction abort, so
* these messages should not raise error states intentionally.
*/
if (log_lock_waits)
{
switch (deadlock_state)
{
case DS_SOFT_DEADLOCK:
ereport(LOG,
(errmsg("deadlock avoided by rearranging lock order")));
break;
case DS_DEADLOCK_NOT_FOUND:
ereport(LOG,
(errmsg("statement waiting for lock for at least %d ms",
DeadlockTimeout)));
break;
case DS_HARD_DEADLOCK:
break; /* ERROR message handled during abort */
default:
break;
}
}
}

10
src/backend/utils/misc/guc.c
View File

@ -10,7 +10,7 @@
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.377 2007/02/23 21:36:18 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.378 2007/03/03 18:46:40 momjian Exp $
*
*--------------------------------------------------------------------
*/
@ -811,6 +811,14 @@ static struct config_bool ConfigureNamesBool[] =
},
#endif
{
{"log_lock_waits", PGC_SIGHUP, LOGGING_WHAT,
gettext_noop("Logs long lock wait events."),
NULL
},
&log_lock_waits,
false, NULL, NULL
},
{
{"log_hostname", PGC_SIGHUP, LOGGING_WHAT,
gettext_noop("Logs the host name in the connection logs."),

2
src/backend/utils/misc/postgresql.conf.sample
View File

@ -340,7 +340,7 @@
# e.g. '<%u%%%d> '
#log_statement = 'none' # none, ddl, mod, all
#log_hostname = off
#log_lock_waits = off # Log lock waits longer than deadlock_timeout
#log_temp_files = -1 # Log temporary files equal or larger
# than the specified number of kilobytes.
# -1 disables; 0 logs all temp files

11
src/include/storage/lock.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.103 2007/01/05 22:19:58 momjian Exp $
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.104 2007/03/03 18:46:40 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -394,6 +394,13 @@ typedef enum
LOCKACQUIRE_ALREADY_HELD /* incremented count for lock already held */
} LockAcquireResult;
/* Deadlock states identified by DeadlockCheck() */
typedef enum
{
DS_DEADLOCK_NOT_FOUND, /* no deadlock found within database server */
DS_SOFT_DEADLOCK, /* deadlock, but lock queues rearrangeable */
DS_HARD_DEADLOCK /* deadlock, no way out but ERROR */
} DeadlockState;
/*
* The lockmgr's shared hash tables are partitioned to reduce contention.
@ -442,7 +449,7 @@ extern void lock_twophase_postcommit(TransactionId xid, uint16 info,
extern void lock_twophase_postabort(TransactionId xid, uint16 info,
void *recdata, uint32 len);
extern bool DeadLockCheck(PGPROC *proc);
extern DeadlockState DeadLockCheck(PGPROC *proc);
extern void DeadLockReport(void);
extern void RememberSimpleDeadLock(PGPROC *proc1,
LOCKMODE lockmode,

3
src/include/storage/proc.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.94 2007/02/15 23:23:23 alvherre Exp $
* $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.95 2007/03/03 18:46:40 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -127,6 +127,7 @@ typedef struct PROC_HDR
/* configurable options */
extern int DeadlockTimeout;
extern int StatementTimeout;
extern bool log_lock_waits;
extern volatile bool cancel_from_timeout;