Boszormenyi Zoltan írta:
> Tom Lane írta:
>
>> Greg Stark <st...@mit.edu> writes:
>>
>>
>>> we already have statement timeout it seems the natural easy to implement
>>> this is with more hairy logic to calculate the timeout until the next of the
>>> three timeouts should fire and set sigalarm. I sympathize with whoever tries
>>> to work that through though, the logic is hairy enough with just the two
>>> variables...but at least we know that sigalarm works or at least it had
>>> better...
>>>
>>>
>> Yeah, that code is ugly as sin already. Maybe there is a way to
>> refactor it so it can scale better? I can't help thinking of Polya's
>> inventor's paradox ("the more general problem may be easier to solve").
>>
>> If we want to do it without any new system-call dependencies I think
>> that's probably the only way. I'm not necessarily against new
>> dependencies, if they're portable --- but it seems these aren't.
>>
>>
>
> Okay, after reading google it seems you're right that OS X lacks
> sem_timedwait(). How about adding a configure check for semtimedop()
> and sem_timedwait() and if they don't exist set a compile time flag
> (HAVE_XXX) and in this case PGSemaphoreTimedLock() would
> behave the same as PGSemaphoreLock() and have an assign_*()
> function that tells the user that the timeout functionality is missing?
> We have precedent for the missing functionality with e.g.
> effective_io_concurrency and ereport() is also allowed in such
> functions, see assign_transaction_read_only().
>
Attached with the proposed modification to lift the portability concerns.
Fixed the missing check for get_rel_name() and one typo ("transation")
Introduced checks for semtimedop() and sem_timedwait() in configure.in
and USE_LOCK_TIMEOUT in port.h depending on
HAVE_DECL_SEMTIMEDOP || HAVE_DECL_SEM_TIMEDWAIT || WIN32
Introduced assign_lock_timeout() GUC validator function that allows
setting the value only from the wired-in-default (0) or from SET statements.
Comments?
Best regards,
Zoltán Böszörményi
--
Bible has answers for everything. Proof:
"But let your communication be, Yea, yea; Nay, nay: for whatsoever is more
than these cometh of evil." (Matthew 5:37) - basics of digital technology.
"May your kingdom come" - superficial description of plate tectonics
----------------------------------
Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
http://www.postgresql.at/
diff -dcrpN --exclude=configure pgsql.orig/configure.in pgsql.1/configure.in
*** pgsql.orig/configure.in 2010-01-17 20:44:10.000000000 +0100
--- pgsql.1/configure.in 2010-01-20 12:13:20.000000000 +0100
*************** if test "$PORTNAME" != "win32"; then
*** 1674,1686 ****
--- 1674,1692 ----
if test x"$USE_NAMED_POSIX_SEMAPHORES" = x"1" ; then
AC_DEFINE(USE_NAMED_POSIX_SEMAPHORES, 1, [Define to select named POSIX semaphores.])
SEMA_IMPLEMENTATION="src/backend/port/posix_sema.c"
+ AC_CHECK_FUNC(sem_timedwait)
+ AC_CHECK_DECLS(sem_timedwait, [], [], [#include <semaphore.h>])
else
if test x"$USE_UNNAMED_POSIX_SEMAPHORES" = x"1" ; then
AC_DEFINE(USE_UNNAMED_POSIX_SEMAPHORES, 1, [Define to select unnamed POSIX semaphores.])
SEMA_IMPLEMENTATION="src/backend/port/posix_sema.c"
+ AC_CHECK_FUNC(sem_timedwait)
+ AC_CHECK_DECLS(sem_timedwait, [], [], [#include <semaphore.h>])
else
AC_DEFINE(USE_SYSV_SEMAPHORES, 1, [Define to select SysV-style semaphores.])
SEMA_IMPLEMENTATION="src/backend/port/sysv_sema.c"
+ AC_CHECK_FUNC(semtimedop)
+ AC_CHECK_DECLS(semtimedop, [], [], [#include <sys/sem.h>])
fi
fi
else
diff -dcrpN --exclude=configure pgsql.orig/doc/src/sgml/config.sgml pgsql.1/doc/src/sgml/config.sgml
*** pgsql.orig/doc/src/sgml/config.sgml 2010-01-15 11:02:47.000000000 +0100
--- pgsql.1/doc/src/sgml/config.sgml 2010-01-20 11:37:23.000000000 +0100
*************** COPY postgres_log FROM '/full/path/to/lo
*** 4236,4241 ****
--- 4236,4265 ----
</listitem>
</varlistentry>
+ <varlistentry id="guc-lock-timeout" xreflabel="lock_timeout">
+ <term><varname>lock_timeout</varname> (<type>integer</type>)</term>
+ <indexterm>
+ <primary><varname>lock_timeout</> configuration parameter</primary>
+ </indexterm>
+ <listitem>
+ <para>
+ Abort any statement that tries to acquire a heavy-weight lock (e.g. rows,
+ pages, tables, indices or other objects) and the lock has to wait more
+ than the specified number of milliseconds, starting from the time the
+ command arrives at the server from the client.
+ If <varname>log_min_error_statement</> is set to <literal>ERROR</> or lower,
+ the statement that timed out will also be logged. A value of zero
+ (the default) turns off the limitation.
+ </para>
+
+ <para>
+ Setting <varname>lock_timeout</> in
+ <filename>postgresql.conf</> is not recommended because it
+ affects all sessions.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-vacuum-freeze-table-age" xreflabel="vacuum_freeze_table_age">
<term><varname>vacuum_freeze_table_age</varname> (<type>integer</type>)</term>
<indexterm>
diff -dcrpN --exclude=configure pgsql.orig/doc/src/sgml/ref/lock.sgml pgsql.1/doc/src/sgml/ref/lock.sgml
*** pgsql.orig/doc/src/sgml/ref/lock.sgml 2009-09-18 08:26:40.000000000 +0200
--- pgsql.1/doc/src/sgml/ref/lock.sgml 2010-01-20 11:37:23.000000000 +0100
*************** LOCK [ TABLE ] [ ONLY ] <replaceable cla
*** 39,46 ****
<literal>NOWAIT</literal> is specified, <command>LOCK
TABLE</command> does not wait to acquire the desired lock: if it
cannot be acquired immediately, the command is aborted and an
! error is emitted. Once obtained, the lock is held for the
! remainder of the current transaction. (There is no <command>UNLOCK
TABLE</command> command; locks are always released at transaction
end.)
</para>
--- 39,49 ----
<literal>NOWAIT</literal> is specified, <command>LOCK
TABLE</command> does not wait to acquire the desired lock: if it
cannot be acquired immediately, the command is aborted and an
! error is emitted. If <varname>lock_timeout</varname> is set to a value
! higher than 0, and the lock cannot be acquired under the specified
! timeout value in milliseconds, the command is aborted and an error
! is emitted. Once obtained, the lock is held for the remainder of
! the current transaction. (There is no <command>UNLOCK
TABLE</command> command; locks are always released at transaction
end.)
</para>
diff -dcrpN --exclude=configure pgsql.orig/doc/src/sgml/ref/select.sgml pgsql.1/doc/src/sgml/ref/select.sgml
*** pgsql.orig/doc/src/sgml/ref/select.sgml 2009-10-29 15:23:52.000000000 +0100
--- pgsql.1/doc/src/sgml/ref/select.sgml 2010-01-20 11:37:23.000000000 +0100
*************** FOR SHARE [ OF <replaceable class="param
*** 1121,1126 ****
--- 1121,1134 ----
</para>
<para>
+ If <literal>NOWAIT</> option is not specified and <varname>lock_timeout</varname>
+ is set to a value higher than 0, and the lock needs to wait more than
+ the specified value in milliseconds, the command reports an error after
+ timing out, rather than waiting indefinitely. The note in the previous
+ paragraph applies to the <varname>lock_timeout</varname>, too.
+ </para>
+
+ <para>
If specific tables are named in <literal>FOR UPDATE</literal>
or <literal>FOR SHARE</literal>,
then only rows coming from those tables are locked; any other
diff -dcrpN --exclude=configure pgsql.orig/src/backend/port/posix_sema.c pgsql.1/src/backend/port/posix_sema.c
*** pgsql.orig/src/backend/port/posix_sema.c 2010-01-03 12:54:22.000000000 +0100
--- pgsql.1/src/backend/port/posix_sema.c 2010-01-20 12:45:19.000000000 +0100
***************
*** 24,29 ****
--- 24,30 ----
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/pg_sema.h"
+ #include "storage/proc.h" /* for LockTimeout */
#ifdef USE_NAMED_POSIX_SEMAPHORES
*************** PGSemaphoreTryLock(PGSemaphore sema)
*** 313,315 ****
--- 314,362 ----
return true;
}
+
+ /*
+ * PGSemaphoreTimedLock
+ *
+ * Lock a semaphore only if able to do so under the lock_timeout
+ */
+ bool
+ PGSemaphoreTimedLock(PGSemaphore sema, bool interruptOK)
+ {
+ #ifdef HAVE_DECL_SEM_TIMEDWAIT
+ int errStatus;
+ struct timespec timeout;
+
+ /*
+ * See notes in sysv_sema.c's implementation of PGSemaphoreLock. Just as
+ * that code does for semop(), we handle both the case where sem_wait()
+ * returns errno == EINTR after a signal, and the case where it just keeps
+ * waiting.
+ */
+ do
+ {
+ ImmediateInterruptOK = interruptOK;
+ CHECK_FOR_INTERRUPTS();
+ if (LockTimeout)
+ {
+ timeout.tv_sec = LockTimeout / 1000;
+ timeout.tv_nsec = (LockTimeout % 1000) * 1000000;
+ errStatus = sem_timedwait(PG_SEM_REF(sema), &timeout);
+ }
+ else
+ errStatus = sem_wait(PG_SEM_REF(sema));
+ ImmediateInterruptOK = false;
+ } while (errStatus < 0 && errno == EINTR);
+
+ if (errStatus < 0)
+ {
+ if (errno == ETIMEDOUT)
+ return false; /* failed to lock it */
+ /* Otherwise we got trouble */
+ elog(FATAL, "sem_wait failed: %m");
+ }
+ #else
+ PGSemaphoreLock(sema, interruptOK);
+ #endif
+ return true;
+ }
diff -dcrpN --exclude=configure pgsql.orig/src/backend/port/sysv_sema.c pgsql.1/src/backend/port/sysv_sema.c
*** pgsql.orig/src/backend/port/sysv_sema.c 2010-01-03 12:54:22.000000000 +0100
--- pgsql.1/src/backend/port/sysv_sema.c 2010-01-20 12:31:11.000000000 +0100
***************
*** 30,35 ****
--- 30,36 ----
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/pg_sema.h"
+ #include "storage/proc.h" /* for LockTimeout */
#ifndef HAVE_UNION_SEMUN
*************** PGSemaphoreTryLock(PGSemaphore sema)
*** 497,499 ****
--- 498,593 ----
return true;
}
+
+ /*
+ * PGSemaphoreTimedLock
+ *
+ * Lock a semaphore only if able to do so under the lock_timeout
+ */
+ bool
+ PGSemaphoreTimedLock(PGSemaphore sema, bool interruptOK)
+ {
+ #ifdef HAVE_DECL_SEMTIMEDOP
+ int errStatus;
+ struct sembuf sops;
+ struct timespec timeout;
+
+ sops.sem_op = -1; /* decrement */
+ sops.sem_flg = 0;
+ sops.sem_num = sema->semNum;
+
+ /*
+ * Note: if errStatus is -1 and errno == EINTR then it means we returned
+ * from the operation prematurely because we were sent a signal. So we
+ * try and lock the semaphore again.
+ *
+ * Each time around the loop, we check for a cancel/die interrupt. On
+ * some platforms, if such an interrupt comes in while we are waiting, it
+ * will cause the semop() call to exit with errno == EINTR, allowing us to
+ * service the interrupt (if not in a critical section already) during the
+ * next loop iteration.
+ *
+ * Once we acquire the lock, we do NOT check for an interrupt before
+ * returning. The caller needs to be able to record ownership of the lock
+ * before any interrupt can be accepted.
+ *
+ * There is a window of a few instructions between CHECK_FOR_INTERRUPTS
+ * and entering the semop() call. If a cancel/die interrupt occurs in
+ * that window, we would fail to notice it until after we acquire the lock
+ * (or get another interrupt to escape the semop()). We can avoid this
+ * problem by temporarily setting ImmediateInterruptOK to true before we
+ * do CHECK_FOR_INTERRUPTS; then, a die() interrupt in this interval will
+ * execute directly. However, there is a huge pitfall: there is another
+ * window of a few instructions after the semop() before we are able to
+ * reset ImmediateInterruptOK. If an interrupt occurs then, we'll lose
+ * control, which means that the lock has been acquired but our caller did
+ * not get a chance to record the fact. Therefore, we only set
+ * ImmediateInterruptOK if the caller tells us it's OK to do so, ie, the
+ * caller does not need to record acquiring the lock. (This is currently
+ * true for lockmanager locks, since the process that granted us the lock
+ * did all the necessary state updates. It's not true for SysV semaphores
+ * used to implement LW locks or emulate spinlocks --- but the wait time
+ * for such locks should not be very long, anyway.)
+ *
+ * On some platforms, signals marked SA_RESTART (which is most, for us)
+ * will not interrupt the semop(); it will just keep waiting. Therefore
+ * it's necessary for cancel/die interrupts to be serviced directly by the
+ * signal handler. On these platforms the behavior is really the same
+ * whether the signal arrives just before the semop() begins, or while it
+ * is waiting. The loop on EINTR is thus important only for other types
+ * of interrupts.
+ */
+ do
+ {
+ ImmediateInterruptOK = interruptOK;
+ CHECK_FOR_INTERRUPTS();
+ if (LockTimeout)
+ {
+ timeout.tv_sec = LockTimeout / 1000;
+ timeout.tv_nsec = (LockTimeout % 1000) * 1000000;
+ errStatus = semtimedop(sema->semId, &sops, 1, &timeout);
+ }
+ else
+ errStatus = semop(sema->semId, &sops, 1);
+ ImmediateInterruptOK = false;
+ } while (errStatus < 0 && errno == EINTR);
+
+ if (errStatus < 0)
+ {
+ /* Expect EAGAIN or EWOULDBLOCK (platform-dependent) */
+ #ifdef EAGAIN
+ if (errno == EAGAIN)
+ return false; /* failed to lock it */
+ #endif
+ #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
+ if (errno == EWOULDBLOCK)
+ return false; /* failed to lock it */
+ #endif
+ /* Otherwise we got trouble */
+ elog(FATAL, "semop(id=%d) failed: %m", sema->semId);
+ }
+ #else
+ PGSemaphoreLock(sema, interruptOK);
+ #endif
+ return true;
+ }
diff -dcrpN --exclude=configure pgsql.orig/src/backend/port/win32_sema.c pgsql.1/src/backend/port/win32_sema.c
*** pgsql.orig/src/backend/port/win32_sema.c 2010-01-03 12:54:22.000000000 +0100
--- pgsql.1/src/backend/port/win32_sema.c 2010-01-20 11:37:23.000000000 +0100
***************
*** 16,21 ****
--- 16,22 ----
#include "miscadmin.h"
#include "storage/ipc.h"
#include "storage/pg_sema.h"
+ #include "storage/proc.h" /* for LockTimeout */
static HANDLE *mySemSet; /* IDs of sema sets acquired so far */
static int numSems; /* number of sema sets acquired so far */
*************** PGSemaphoreTryLock(PGSemaphore sema)
*** 205,207 ****
--- 206,266 ----
/* keep compiler quiet */
return false;
}
+
+ /*
+ * PGSemaphoreTimedLock
+ *
+ * Lock a semaphore only if able to do so under the lock_timeout
+ * Serve the interrupt if interruptOK is true.
+ */
+ bool
+ PGSemaphoreTimedLock(PGSemaphore sema, bool interruptOK)
+ {
+ DWORD ret;
+ HANDLE wh[2];
+
+ wh[0] = *sema;
+ wh[1] = pgwin32_signal_event;
+
+ /*
+ * As in other implementations of PGSemaphoreLock, we need to check for
+ * cancel/die interrupts each time through the loop. But here, there is
+ * no hidden magic about whether the syscall will internally service a
+ * signal --- we do that ourselves.
+ */
+ do
+ {
+ ImmediateInterruptOK = interruptOK;
+ CHECK_FOR_INTERRUPTS();
+
+ errno = 0;
+ ret = WaitForMultipleObjectsEx(2, wh, FALSE, LockTimeout ? LockTimeout : INFINITE, TRUE);
+
+ if (ret == WAIT_OBJECT_0)
+ {
+ /* We got it! */
+ return true;
+ }
+ else if (ret == WAIT_TIMEOUT)
+ {
+ /* Can't get it */
+ errno = EAGAIN;
+ return false;
+ }
+ else if (ret == WAIT_OBJECT_0 + 1)
+ {
+ /* Signal event is set - we have a signal to deliver */
+ pgwin32_dispatch_queued_signals();
+ errno = EINTR;
+ }
+ else
+ /* Otherwise we are in trouble */
+ errno = EIDRM;
+
+ ImmediateInterruptOK = false;
+ } while (errno == EINTR);
+
+ if (errno != 0)
+ ereport(FATAL,
+ (errmsg("could not lock semaphore: error code %d", (int) GetLastError())));
+ }
diff -dcrpN --exclude=configure pgsql.orig/src/backend/storage/lmgr/lmgr.c pgsql.1/src/backend/storage/lmgr/lmgr.c
*** pgsql.orig/src/backend/storage/lmgr/lmgr.c 2010-01-03 12:54:25.000000000 +0100
--- pgsql.1/src/backend/storage/lmgr/lmgr.c 2010-01-20 12:43:09.000000000 +0100
***************
*** 19,26 ****
--- 19,29 ----
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
+ #include "catalog/pg_database.h"
#include "miscadmin.h"
#include "storage/lmgr.h"
+ #include "utils/lsyscache.h"
+ #include "storage/proc.h"
#include "storage/procarray.h"
#include "utils/inval.h"
*************** LockRelationOid(Oid relid, LOCKMODE lock
*** 78,83 ****
--- 81,101 ----
res = LockAcquire(&tag, lockmode, false, false);
+ if (res == LOCKACQUIRE_NOT_AVAIL)
+ {
+ char *relname = get_rel_name(relid);
+ if (relname)
+ ereport(ERROR,
+ (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
+ errmsg("could not obtain lock on relation \"%s\"",
+ relname)));
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
+ errmsg("could not obtain lock on relation with OID %u",
+ relid)));
+ }
+
/*
* Now that we have the lock, check for invalidation messages, so that we
* will update or flush any stale relcache entry before we try to use it.
*************** LockRelation(Relation relation, LOCKMODE
*** 173,178 ****
--- 191,202 ----
res = LockAcquire(&tag, lockmode, false, false);
+ if (res == LOCKACQUIRE_NOT_AVAIL)
+ ereport(ERROR,
+ (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
+ errmsg("could not obtain lock on relation \"%s\"",
+ RelationGetRelationName(relation))));
+
/*
* Now that we have the lock, check for invalidation messages; see notes
* in LockRelationOid.
*************** LockRelationIdForSession(LockRelId *reli
*** 250,256 ****
SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);
! (void) LockAcquire(&tag, lockmode, true, false);
}
/*
--- 274,293 ----
SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);
! if (LockAcquire(&tag, lockmode, true, false) == LOCKACQUIRE_NOT_AVAIL)
! {
! char *relname = get_rel_name(relid->relId);
! if (relname)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on relation \"%s\"",
! relname)));
! else
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on relation with OID %u",
! relid)));
! }
}
/*
*************** LockRelationForExtension(Relation relati
*** 285,291 ****
relation->rd_lockInfo.lockRelId.dbId,
relation->rd_lockInfo.lockRelId.relId);
! (void) LockAcquire(&tag, lockmode, false, false);
}
/*
--- 322,332 ----
relation->rd_lockInfo.lockRelId.dbId,
relation->rd_lockInfo.lockRelId.relId);
! if (LockAcquire(&tag, lockmode, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on index \"%s\"",
! RelationGetRelationName(relation))));
}
/*
*************** LockPage(Relation relation, BlockNumber
*** 319,325 ****
relation->rd_lockInfo.lockRelId.relId,
blkno);
! (void) LockAcquire(&tag, lockmode, false, false);
}
/*
--- 360,370 ----
relation->rd_lockInfo.lockRelId.relId,
blkno);
! if (LockAcquire(&tag, lockmode, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on page %u of relation \"%s\"",
! blkno, RelationGetRelationName(relation))));
}
/*
*************** LockTuple(Relation relation, ItemPointer
*** 375,381 ****
ItemPointerGetBlockNumber(tid),
ItemPointerGetOffsetNumber(tid));
! (void) LockAcquire(&tag, lockmode, false, false);
}
/*
--- 420,430 ----
ItemPointerGetBlockNumber(tid),
ItemPointerGetOffsetNumber(tid));
! if (LockAcquire(&tag, lockmode, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on row in relation \"%s\"",
! RelationGetRelationName(relation))));
}
/*
*************** XactLockTableInsert(TransactionId xid)
*** 429,435 ****
SET_LOCKTAG_TRANSACTION(tag, xid);
! (void) LockAcquire(&tag, ExclusiveLock, false, false);
}
/*
--- 478,487 ----
SET_LOCKTAG_TRANSACTION(tag, xid);
! if (LockAcquire(&tag, ExclusiveLock, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on transaction with ID %u", xid)));
}
/*
*************** XactLockTableWait(TransactionId xid)
*** 473,479 ****
SET_LOCKTAG_TRANSACTION(tag, xid);
! (void) LockAcquire(&tag, ShareLock, false, false);
LockRelease(&tag, ShareLock, false);
--- 525,534 ----
SET_LOCKTAG_TRANSACTION(tag, xid);
! if (LockAcquire(&tag, ShareLock, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on transaction with ID %u", xid)));
LockRelease(&tag, ShareLock, false);
*************** VirtualXactLockTableInsert(VirtualTransa
*** 531,537 ****
SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
! (void) LockAcquire(&tag, ExclusiveLock, false, false);
}
/*
--- 586,596 ----
SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
! if (LockAcquire(&tag, ExclusiveLock, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on virtual transaction with ID %u",
! vxid.localTransactionId)));
}
/*
*************** VirtualXactLockTableWait(VirtualTransact
*** 549,555 ****
SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
! (void) LockAcquire(&tag, ShareLock, false, false);
LockRelease(&tag, ShareLock, false);
}
--- 608,618 ----
SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
! if (LockAcquire(&tag, ShareLock, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on virtual transaction with ID %u",
! vxid.localTransactionId)));
LockRelease(&tag, ShareLock, false);
}
*************** LockDatabaseObject(Oid classid, Oid obji
*** 598,604 ****
objid,
objsubid);
! (void) LockAcquire(&tag, lockmode, false, false);
}
/*
--- 661,671 ----
objid,
objsubid);
! if (LockAcquire(&tag, lockmode, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on class:object: %u:%u",
! classid, objid)));
}
/*
*************** LockSharedObject(Oid classid, Oid objid,
*** 636,642 ****
objid,
objsubid);
! (void) LockAcquire(&tag, lockmode, false, false);
/* Make sure syscaches are up-to-date with any changes we waited for */
AcceptInvalidationMessages();
--- 703,713 ----
objid,
objsubid);
! if (LockAcquire(&tag, lockmode, false, false) == LOCKACQUIRE_NOT_AVAIL)
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on class:object: %u:%u",
! classid, objid)));
/* Make sure syscaches are up-to-date with any changes we waited for */
AcceptInvalidationMessages();
*************** LockSharedObjectForSession(Oid classid,
*** 678,684 ****
objid,
objsubid);
! (void) LockAcquire(&tag, lockmode, true, false);
}
/*
--- 749,770 ----
objid,
objsubid);
! if (LockAcquire(&tag, lockmode, true, false) == LOCKACQUIRE_NOT_AVAIL)
! switch(classid)
! {
! case DatabaseRelationId:
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on database with ID %u",
! objid)));
! break;
! default:
! ereport(ERROR,
! (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
! errmsg("could not obtain lock on class:object: %u:%u",
! classid, objid)));
! break;
! }
}
/*
diff -dcrpN --exclude=configure pgsql.orig/src/backend/storage/lmgr/lock.c pgsql.1/src/backend/storage/lmgr/lock.c
*** pgsql.orig/src/backend/storage/lmgr/lock.c 2010-01-03 12:54:25.000000000 +0100
--- pgsql.1/src/backend/storage/lmgr/lock.c 2010-01-20 11:37:23.000000000 +0100
*************** PROCLOCK_PRINT(const char *where, const
*** 255,261 ****
static uint32 proclock_hash(const void *key, Size keysize);
static void RemoveLocalLock(LOCALLOCK *locallock);
static void GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner);
! static void WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner);
static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
PROCLOCK *proclock, LockMethod lockMethodTable);
static void CleanUpLock(LOCK *lock, PROCLOCK *proclock,
--- 255,261 ----
static uint32 proclock_hash(const void *key, Size keysize);
static void RemoveLocalLock(LOCALLOCK *locallock);
static void GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner);
! static int WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner);
static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
PROCLOCK *proclock, LockMethod lockMethodTable);
static void CleanUpLock(LOCK *lock, PROCLOCK *proclock,
*************** ProcLockHashCode(const PROCLOCKTAG *proc
*** 451,457 ****
* dontWait: if true, don't wait to acquire lock
*
* Returns one of:
! * LOCKACQUIRE_NOT_AVAIL lock not available, and dontWait=true
* LOCKACQUIRE_OK lock successfully acquired
* LOCKACQUIRE_ALREADY_HELD incremented count for lock already held
*
--- 451,457 ----
* dontWait: if true, don't wait to acquire lock
*
* Returns one of:
! * LOCKACQUIRE_NOT_AVAIL lock not available, either dontWait=true or timeout
* LOCKACQUIRE_OK lock successfully acquired
* LOCKACQUIRE_ALREADY_HELD incremented count for lock already held
*
*************** LockAcquireExtended(const LOCKTAG *lockt
*** 849,855 ****
locktag->locktag_type,
lockmode);
! WaitOnLock(locallock, owner);
TRACE_POSTGRESQL_LOCK_WAIT_DONE(locktag->locktag_field1,
locktag->locktag_field2,
--- 849,855 ----
locktag->locktag_type,
lockmode);
! status = WaitOnLock(locallock, owner);
TRACE_POSTGRESQL_LOCK_WAIT_DONE(locktag->locktag_field1,
locktag->locktag_field2,
*************** LockAcquireExtended(const LOCKTAG *lockt
*** 864,883 ****
* done when the lock was granted to us --- see notes in WaitOnLock.
*/
! /*
! * Check the proclock entry status, in case something in the ipc
! * communication doesn't work correctly.
! */
! if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
{
! PROCLOCK_PRINT("LockAcquire: INCONSISTENT", proclock);
! LOCK_PRINT("LockAcquire: INCONSISTENT", lock, lockmode);
! /* Should we retry ? */
! LWLockRelease(partitionLock);
! elog(ERROR, "LockAcquire failed");
}
- PROCLOCK_PRINT("LockAcquire: granted", proclock);
- LOCK_PRINT("LockAcquire: granted", lock, lockmode);
}
LWLockRelease(partitionLock);
--- 864,895 ----
* done when the lock was granted to us --- see notes in WaitOnLock.
*/
! switch (status)
{
! case STATUS_OK:
! /*
! * Check the proclock entry status, in case something in the ipc
! * communication doesn't work correctly.
! */
! if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
! {
! PROCLOCK_PRINT("LockAcquire: INCONSISTENT", proclock);
! LOCK_PRINT("LockAcquire: INCONSISTENT", lock, lockmode);
! /* Should we retry ? */
! LWLockRelease(partitionLock);
! elog(ERROR, "LockAcquire failed");
! }
! PROCLOCK_PRINT("LockAcquire: granted", proclock);
! LOCK_PRINT("LockAcquire: granted", lock, lockmode);
! break;
! case STATUS_WAITING:
! PROCLOCK_PRINT("LockAcquire: timed out", proclock);
! LOCK_PRINT("LockAcquire: timed out", lock, lockmode);
! break;
! default:
! elog(ERROR, "LockAcquire invalid status");
! break;
}
}
LWLockRelease(partitionLock);
*************** LockAcquireExtended(const LOCKTAG *lockt
*** 903,909 ****
locktag->locktag_field2);
}
! return LOCKACQUIRE_OK;
}
/*
--- 915,921 ----
locktag->locktag_field2);
}
! return (status == STATUS_OK ? LOCKACQUIRE_OK : LOCKACQUIRE_NOT_AVAIL);
}
/*
*************** GrantAwaitedLock(void)
*** 1181,1194 ****
* Caller must have set MyProc->heldLocks to reflect locks already held
* on the lockable object by this process.
*
* The appropriate partition lock must be held at entry.
*/
! static void
WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
{
LOCKMETHODID lockmethodid = LOCALLOCK_LOCKMETHOD(*locallock);
LockMethod lockMethodTable = LockMethods[lockmethodid];
char *volatile new_status = NULL;
LOCK_PRINT("WaitOnLock: sleeping on lock",
locallock->lock, locallock->tag.mode);
--- 1193,1212 ----
* Caller must have set MyProc->heldLocks to reflect locks already held
* on the lockable object by this process.
*
+ * Result: returns value of ProcSleep()
+ * STATUS_OK if we acquired the lock
+ * STATUS_ERROR if not (deadlock)
+ * STATUS_WAITING if not (timeout)
+ *
* The appropriate partition lock must be held at entry.
*/
! static int
WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
{
LOCKMETHODID lockmethodid = LOCALLOCK_LOCKMETHOD(*locallock);
LockMethod lockMethodTable = LockMethods[lockmethodid];
char *volatile new_status = NULL;
+ int wait_status;
LOCK_PRINT("WaitOnLock: sleeping on lock",
locallock->lock, locallock->tag.mode);
*************** WaitOnLock(LOCALLOCK *locallock, Resourc
*** 1230,1237 ****
*/
PG_TRY();
{
! if (ProcSleep(locallock, lockMethodTable) != STATUS_OK)
{
/*
* We failed as a result of a deadlock, see CheckDeadLock(). Quit
* now.
--- 1248,1260 ----
*/
PG_TRY();
{
! wait_status = ProcSleep(locallock, lockMethodTable);
! switch (wait_status)
{
+ case STATUS_OK:
+ case STATUS_WAITING:
+ break;
+ default:
/*
* We failed as a result of a deadlock, see CheckDeadLock(). Quit
* now.
*************** WaitOnLock(LOCALLOCK *locallock, Resourc
*** 1276,1283 ****
pfree(new_status);
}
! LOCK_PRINT("WaitOnLock: wakeup on lock",
locallock->lock, locallock->tag.mode);
}
/*
--- 1299,1312 ----
pfree(new_status);
}
! if (wait_status == STATUS_OK)
! LOCK_PRINT("WaitOnLock: wakeup on lock",
! locallock->lock, locallock->tag.mode);
! else if (wait_status == STATUS_WAITING)
! LOCK_PRINT("WaitOnLock: timeout on lock",
locallock->lock, locallock->tag.mode);
+
+ return wait_status;
}
/*
diff -dcrpN --exclude=configure pgsql.orig/src/backend/storage/lmgr/proc.c pgsql.1/src/backend/storage/lmgr/proc.c
*** pgsql.orig/src/backend/storage/lmgr/proc.c 2010-01-17 20:44:18.000000000 +0100
--- pgsql.1/src/backend/storage/lmgr/proc.c 2010-01-20 11:37:23.000000000 +0100
***************
*** 47,56 ****
#include "storage/procarray.h"
#include "storage/spin.h"
-
/* GUC variables */
int DeadlockTimeout = 1000;
int StatementTimeout = 0;
bool log_lock_waits = false;
/* Pointer to this process's PGPROC struct, if any */
--- 47,56 ----
#include "storage/procarray.h"
#include "storage/spin.h"
/* GUC variables */
int DeadlockTimeout = 1000;
int StatementTimeout = 0;
+ int LockTimeout = 0;
bool log_lock_waits = false;
/* Pointer to this process's PGPROC struct, if any */
*************** ProcQueueInit(PROC_QUEUE *queue)
*** 749,755 ****
* The lock table's partition lock must be held at entry, and will be held
* at exit.
*
! * Result: STATUS_OK if we acquired the lock, STATUS_ERROR if not (deadlock).
*
* ASSUME: that no one will fiddle with the queue until after
* we release the partition lock.
--- 749,758 ----
* The lock table's partition lock must be held at entry, and will be held
* at exit.
*
! * Result:
! * STATUS_OK if we acquired the lock
! * STATUS_ERROR if not (deadlock)
! * STATUS_WAITING if not (timeout)
*
* ASSUME: that no one will fiddle with the queue until after
* we release the partition lock.
*************** ProcSleep(LOCALLOCK *locallock, LockMeth
*** 771,776 ****
--- 774,780 ----
LOCKMASK myHeldLocks = MyProc->heldLocks;
bool early_deadlock = false;
bool allow_autovacuum_cancel = true;
+ bool timeout_detected = false;
int myWaitStatus;
PGPROC *proc;
int i;
*************** ProcSleep(LOCALLOCK *locallock, LockMeth
*** 903,909 ****
elog(FATAL, "could not set timer for process wakeup");
/*
! * If someone wakes us between LWLockRelease and PGSemaphoreLock,
* PGSemaphoreLock will not block. The wakeup is "saved" by the semaphore
* implementation. While this is normally good, there are cases where a
* saved wakeup might be leftover from a previous operation (for example,
--- 907,913 ----
elog(FATAL, "could not set timer for process wakeup");
/*
! * If someone wakes us between LWLockRelease and PGSemaphoreTimedLock,
* PGSemaphoreLock will not block. The wakeup is "saved" by the semaphore
* implementation. While this is normally good, there are cases where a
* saved wakeup might be leftover from a previous operation (for example,
*************** ProcSleep(LOCALLOCK *locallock, LockMeth
*** 921,927 ****
*/
do
{
! PGSemaphoreLock(&MyProc->sem, true);
/*
* waitStatus could change from STATUS_WAITING to something else
--- 925,935 ----
*/
do
{
! if (!PGSemaphoreTimedLock(&MyProc->sem, true))
! {
! timeout_detected = true;
! break;
! }
/*
* waitStatus could change from STATUS_WAITING to something else
*************** ProcSleep(LOCALLOCK *locallock, LockMeth
*** 1061,1066 ****
--- 1069,1082 ----
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
/*
+ * If we're in timeout, so we're not waiting anymore and
+ * we're not the one that the lock will be granted to.
+ * So remove ourselves from the wait queue.
+ */
+ if (timeout_detected)
+ RemoveFromWaitQueue(MyProc, hashcode);
+
+ /*
* We no longer want LockWaitCancel to do anything.
*/
lockAwaited = NULL;
*************** ProcSleep(LOCALLOCK *locallock, LockMeth
*** 1074,1081 ****
/*
* We don't have to do anything else, because the awaker did all the
* necessary update of the lock table and MyProc.
*/
! return MyProc->waitStatus;
}
--- 1090,1099 ----
/*
* We don't have to do anything else, because the awaker did all the
* necessary update of the lock table and MyProc.
+ * RemoveFromWaitQueue() have set MyProc->waitStatus = STATUS_ERROR,
+ * we need to distinguish this case.
*/
! return (timeout_detected ? STATUS_WAITING : MyProc->waitStatus);
}
diff -dcrpN --exclude=configure pgsql.orig/src/backend/utils/misc/guc.c pgsql.1/src/backend/utils/misc/guc.c
*** pgsql.orig/src/backend/utils/misc/guc.c 2010-01-15 11:02:50.000000000 +0100
--- pgsql.1/src/backend/utils/misc/guc.c 2010-01-20 13:09:45.000000000 +0100
*************** static bool assign_autovacuum_max_worker
*** 175,180 ****
--- 175,181 ----
static bool assign_effective_io_concurrency(int newval, bool doit, GucSource source);
static const char *assign_pgstat_temp_directory(const char *newval, bool doit, GucSource source);
static const char *assign_application_name(const char *newval, bool doit, GucSource source);
+ static bool assign_lock_timeout(int newval, bool doit, GucSource source);
static char *config_enum_get_options(struct config_enum * record,
const char *prefix, const char *suffix,
*************** static struct config_int ConfigureNamesI
*** 1587,1592 ****
--- 1588,1603 ----
},
{
+ {"lock_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
+ gettext_noop("Sets the maximum allowed timeout for any lock taken by a statement."),
+ gettext_noop("A value of 0 turns off the timeout."),
+ GUC_UNIT_MS
+ },
+ &LockTimeout,
+ 0, 0, INT_MAX, assign_lock_timeout, NULL
+ },
+
+ {
{"vacuum_freeze_min_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
gettext_noop("Minimum age at which VACUUM should freeze a table row."),
NULL
*************** assign_application_name(const char *newv
*** 7860,7863 ****
--- 7871,7891 ----
return newval;
}
+ static bool
+ assign_lock_timeout(int newval, bool doit, GucSource source)
+ {
+ #ifdef USE_LOCK_TIMEOUT
+ /*
+ * Only allow setting from the wired-in default (0) or
+ * from SET statements to ensure proper system stability.
+ */
+ return (source == PGC_S_DEFAULT || source == PGC_S_SESSION);
+ #else
+ ereport(GUC_complaint_elevel(source),
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("your system doesn't support timed semaphores")));
+ return false;
+ #endif
+ }
+
#include "guc-file.c"
diff -dcrpN --exclude=configure pgsql.orig/src/backend/utils/misc/postgresql.conf.sample pgsql.1/src/backend/utils/misc/postgresql.conf.sample
*** pgsql.orig/src/backend/utils/misc/postgresql.conf.sample 2010-01-15 11:02:50.000000000 +0100
--- pgsql.1/src/backend/utils/misc/postgresql.conf.sample 2010-01-20 11:39:20.000000000 +0100
***************
*** 481,486 ****
--- 481,489 ----
#------------------------------------------------------------------------------
#deadlock_timeout = 1s
+ #lock_timeout = 0 # timeout value for heavy-weight locks
+ # taken by statements. 0 disables timeout
+ # unit in milliseconds, default is 0
#max_locks_per_transaction = 64 # min 10
# (change requires restart)
# Note: Each lock table slot uses ~270 bytes of shared memory, and there are
diff -dcrpN --exclude=configure pgsql.orig/src/include/pg_config.h.in pgsql.1/src/include/pg_config.h.in
*** pgsql.orig/src/include/pg_config.h.in 2010-01-08 14:37:13.000000000 +0100
--- pgsql.1/src/include/pg_config.h.in 2010-01-20 12:13:31.000000000 +0100
***************
*** 108,113 ****
--- 108,121 ----
don't. */
#undef HAVE_DECL_POSIX_FADVISE
+ /* Define to 1 if you have the declaration of `semtimedop', and to 0 if you
+ don't. */
+ #undef HAVE_DECL_SEMTIMEDOP
+
+ /* Define to 1 if you have the declaration of `sem_timedwait', and to 0 if you
+ don't. */
+ #undef HAVE_DECL_SEM_TIMEDWAIT
+
/* Define to 1 if you have the declaration of `snprintf', and to 0 if you
don't. */
#undef HAVE_DECL_SNPRINTF
diff -dcrpN --exclude=configure pgsql.orig/src/include/port.h pgsql.1/src/include/port.h
*** pgsql.orig/src/include/port.h 2010-01-10 15:49:34.000000000 +0100
--- pgsql.1/src/include/port.h 2010-01-20 12:25:33.000000000 +0100
*************** extern BOOL AddUserToTokenDacl(HANDLE hT
*** 109,114 ****
--- 109,118 ----
#define DEVTTY "/dev/tty"
#endif
+ #if defined(WIN32) || defined(HAVE_DECL_SEMTIMEDOP) || defined(HAVE_DECL_SEM_TIMEDWAIT)
+ #define USE_LOCK_TIMEOUT 1
+ #endif
+
/*
* Win32 needs double quotes at the beginning and end of system()
* strings. If not, it gets confused with multiple quoted strings.
diff -dcrpN --exclude=configure pgsql.orig/src/include/storage/pg_sema.h pgsql.1/src/include/storage/pg_sema.h
*** pgsql.orig/src/include/storage/pg_sema.h 2010-01-03 12:54:39.000000000 +0100
--- pgsql.1/src/include/storage/pg_sema.h 2010-01-20 11:37:23.000000000 +0100
*************** extern void PGSemaphoreUnlock(PGSemaphor
*** 80,83 ****
--- 80,86 ----
/* Lock a semaphore only if able to do so without blocking */
extern bool PGSemaphoreTryLock(PGSemaphore sema);
+ /* Lock a semaphore only if able to do so under the lock_timeout */
+ extern bool PGSemaphoreTimedLock(PGSemaphore sema, bool interruptOK);
+
#endif /* PG_SEMA_H */
diff -dcrpN --exclude=configure pgsql.orig/src/include/storage/proc.h pgsql.1/src/include/storage/proc.h
*** pgsql.orig/src/include/storage/proc.h 2010-01-17 20:44:22.000000000 +0100
--- pgsql.1/src/include/storage/proc.h 2010-01-20 11:37:23.000000000 +0100
*************** typedef struct PROC_HDR
*** 161,166 ****
--- 161,167 ----
/* configurable options */
extern int DeadlockTimeout;
extern int StatementTimeout;
+ extern int LockTimeout;
extern bool log_lock_waits;
extern volatile bool cancel_from_timeout;
--
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