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-rw-r--r--src/backend/storage/ipc/procsignal.c5
-rw-r--r--src/backend/storage/ipc/standby.c62
-rw-r--r--src/backend/storage/lmgr/proc.c14
-rw-r--r--src/backend/tcop/postgres.c16
-rw-r--r--src/backend/utils/misc/guc.c4
5 files changed, 79 insertions, 22 deletions
diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c
index 6c38d423f2..03f61b20ee 100644
--- a/src/backend/storage/ipc/procsignal.c
+++ b/src/backend/storage/ipc/procsignal.c
@@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/ipc/procsignal.c,v 1.4 2010/01/23 16:37:12 sriggs Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/ipc/procsignal.c,v 1.5 2010/02/13 01:32:19 sriggs Exp $
*
*-------------------------------------------------------------------------
*/
@@ -272,6 +272,9 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT))
RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT);
+ if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK))
+ RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+
if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))
RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index 3b3534886c..fc4295465a 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -11,7 +11,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/ipc/standby.c,v 1.11 2010/02/11 19:35:22 sriggs Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/ipc/standby.c,v 1.12 2010/02/13 01:32:19 sriggs Exp $
*
*-------------------------------------------------------------------------
*/
@@ -127,6 +127,9 @@ WaitExceedsMaxStandbyDelay(void)
long delay_secs;
int delay_usecs;
+ if (MaxStandbyDelay == -1)
+ return false;
+
/* Are we past max_standby_delay? */
TimestampDifference(GetLatestXLogTime(), GetCurrentTimestamp(),
&delay_secs, &delay_usecs);
@@ -351,15 +354,15 @@ ResolveRecoveryConflictWithLock(Oid dbOid, Oid relOid)
* they hold one of the buffer pins that is blocking Startup process. If so,
* backends will take an appropriate error action, ERROR or FATAL.
*
- * A secondary purpose of this is to avoid deadlocks that might occur between
- * the Startup process and lock waiters. Deadlocks occur because if queries
+ * We also check for deadlocks before we wait, though applications that cause
+ * these will be extremely rare. Deadlocks occur because if queries
* wait on a lock, that must be behind an AccessExclusiveLock, which can only
- * be clared if the Startup process replays a transaction completion record.
- * If Startup process is waiting then that is a deadlock. If we allowed a
- * setting of max_standby_delay that meant "wait forever" we would then need
- * special code to protect against deadlock. Such deadlocks are rare, so the
- * code would be almost certainly buggy, so we avoid both long waits and
- * deadlocks using the same mechanism.
+ * be cleared if the Startup process replays a transaction completion record.
+ * If Startup process is also waiting then that is a deadlock. The deadlock
+ * can occur if the query is waiting and then the Startup sleeps, or if
+ * Startup is sleeping and the the query waits on a lock. We protect against
+ * only the former sequence here, the latter sequence is checked prior to
+ * the query sleeping, in CheckRecoveryConflictDeadlock().
*/
void
ResolveRecoveryConflictWithBufferPin(void)
@@ -368,11 +371,23 @@ ResolveRecoveryConflictWithBufferPin(void)
Assert(InHotStandby);
- /*
- * Signal immediately or set alarm for later.
- */
if (MaxStandbyDelay == 0)
- SendRecoveryConflictWithBufferPin();
+ {
+ /*
+ * We don't want to wait, so just tell everybody holding the pin to
+ * get out of town.
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
+ }
+ else if (MaxStandbyDelay == -1)
+ {
+ /*
+ * Send out a request to check for buffer pin deadlocks before we wait.
+ * This is fairly cheap, so no need to wait for deadlock timeout before
+ * trying to send it out.
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+ }
else
{
TimestampTz now;
@@ -386,7 +401,12 @@ ResolveRecoveryConflictWithBufferPin(void)
&standby_delay_secs, &standby_delay_usecs);
if (standby_delay_secs >= MaxStandbyDelay)
- SendRecoveryConflictWithBufferPin();
+ {
+ /*
+ * We're already behind, so clear a path as quickly as possible.
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
+ }
else
{
TimestampTz fin_time; /* Expected wake-up time by timer */
@@ -394,6 +414,13 @@ ResolveRecoveryConflictWithBufferPin(void)
int timer_delay_usecs = 0;
/*
+ * Send out a request to check for buffer pin deadlocks before we wait.
+ * This is fairly cheap, so no need to wait for deadlock timeout before
+ * trying to send it out.
+ */
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+
+ /*
* How much longer we should wait?
*/
timer_delay_secs = MaxStandbyDelay - standby_delay_secs;
@@ -435,15 +462,18 @@ ResolveRecoveryConflictWithBufferPin(void)
}
void
-SendRecoveryConflictWithBufferPin(void)
+SendRecoveryConflictWithBufferPin(ProcSignalReason reason)
{
+ Assert(reason == PROCSIG_RECOVERY_CONFLICT_BUFFERPIN ||
+ reason == PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
+
/*
* We send signal to all backends to ask them if they are holding
* the buffer pin which is delaying the Startup process. We must
* not set the conflict flag yet, since most backends will be innocent.
* Let the SIGUSR1 handling in each backend decide their own fate.
*/
- CancelDBBackends(InvalidOid, PROCSIG_RECOVERY_CONFLICT_BUFFERPIN, false);
+ CancelDBBackends(InvalidOid, reason, false);
}
/*
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index a96a558da3..1e103743b2 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.215 2010/02/08 04:33:54 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.216 2010/02/13 01:32:19 sriggs Exp $
*
*-------------------------------------------------------------------------
*/
@@ -45,6 +45,7 @@
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/procarray.h"
+#include "storage/procsignal.h"
#include "storage/spin.h"
@@ -556,6 +557,15 @@ HaveNFreeProcs(int n)
return (n <= 0);
}
+bool
+IsWaitingForLock(void)
+{
+ if (lockAwaited == NULL)
+ return false;
+
+ return true;
+}
+
/*
* Cancel any pending wait for lock, when aborting a transaction.
*
@@ -1670,7 +1680,7 @@ CheckStandbyTimeout(void)
now = GetCurrentTimestamp();
if (now >= statement_fin_time)
- SendRecoveryConflictWithBufferPin();
+ SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
else
{
/* Not time yet, so (re)schedule the interrupt */
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 35a4d087ce..8d33000e61 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.587 2010/01/23 17:04:05 sriggs Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.588 2010/02/13 01:32:19 sriggs Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@@ -2278,6 +2278,9 @@ errdetail_recovery_conflict(void)
case PROCSIG_RECOVERY_CONFLICT_SNAPSHOT:
errdetail("User query might have needed to see row versions that must be removed.");
break;
+ case PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK:
+ errdetail("User transaction caused buffer deadlock with recovery.");
+ break;
case PROCSIG_RECOVERY_CONFLICT_DATABASE:
errdetail("User was connected to a database that must be dropped.");
break;
@@ -2754,6 +2757,15 @@ RecoveryConflictInterrupt(ProcSignalReason reason)
RecoveryConflictReason = reason;
switch (reason)
{
+ case PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK:
+ /*
+ * If we aren't waiting for a lock we can never deadlock.
+ */
+ if (!IsWaitingForLock())
+ return;
+
+ /* Intentional drop through to check wait for pin */
+
case PROCSIG_RECOVERY_CONFLICT_BUFFERPIN:
/*
* If we aren't blocking the Startup process there is
@@ -2819,6 +2831,8 @@ RecoveryConflictInterrupt(ProcSignalReason reason)
elog(FATAL, "Unknown conflict mode");
}
+ Assert(RecoveryConflictPending && (QueryCancelPending || ProcDiePending));
+
/*
* If it's safe to interrupt, and we're waiting for input or a lock,
* service the interrupt immediately
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 642fc6796a..fd533a1e58 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -10,7 +10,7 @@
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.538 2010/02/01 13:40:28 sriggs Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.539 2010/02/13 01:32:20 sriggs Exp $
*
*--------------------------------------------------------------------
*/
@@ -1381,7 +1381,7 @@ static struct config_int ConfigureNamesInt[] =
NULL
},
&MaxStandbyDelay,
- 30, 0, INT_MAX, NULL, NULL
+ 30, -1, INT_MAX, NULL, NULL
},
{
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