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In HS, Startup process sets SIGALRM when waiting for buffer pin. If
authorSimon Riggs <simon@2ndQuadrant.com>
Sat, 23 Jan 2010 16:37:12 +0000 (16:37 +0000)
committerSimon Riggs <simon@2ndQuadrant.com>
Sat, 23 Jan 2010 16:37:12 +0000 (16:37 +0000)
woken by alarm we send SIGUSR1 to all backends requesting that they
check to see if they are blocking Startup process. If so, they throw
ERROR/FATAL as for other conflict resolutions. Deadlock stop gap
removed. max_standby_delay = -1 option removed to prevent deadlock.

16 files changed:
doc/src/sgml/backup.sgml
doc/src/sgml/config.sgml
src/backend/access/transam/xlog.c
src/backend/storage/buffer/bufmgr.c
src/backend/storage/ipc/procarray.c
src/backend/storage/ipc/procsignal.c
src/backend/storage/ipc/standby.c
src/backend/storage/lmgr/lock.c
src/backend/storage/lmgr/proc.c
src/backend/tcop/postgres.c
src/backend/utils/misc/guc.c
src/include/storage/bufmgr.h
src/include/storage/proc.h
src/include/storage/procarray.h
src/include/storage/procsignal.h
src/include/storage/standby.h

index da52f42..a2c1375 100644 (file)
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.136 2010/01/15 09:18:56 heikki Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.137 2010/01/23 16:37:12 sriggs Exp $ -->
 
 <chapter id="backup">
  <title>Backup and Restore</title>
@@ -2399,7 +2399,7 @@ primary_conninfo = 'host=192.168.1.50 port=5432 user=foo password=foopass'
        </listitem>
        <listitem>
         <para>
-         Waiting to acquire buffer cleanup locks (for which there is no time out)
+         Waiting to acquire buffer cleanup locks
         </para>
        </listitem>
        <listitem>
@@ -2536,11 +2536,7 @@ primary_conninfo = 'host=192.168.1.50 port=5432 user=foo password=foopass'
     Three-way deadlocks are possible between AccessExclusiveLocks arriving from
     the primary, cleanup WAL records that require buffer cleanup locks and
     user requests that are waiting behind replayed AccessExclusiveLocks. Deadlocks
-    are currently resolved by the cancellation of user processes that would
-    need to wait on a lock. This is heavy-handed and generates more query
-    cancellations than we need to, though does remove the possibility of deadlock.
-    This behaviour is expected to improve substantially for the main release
-    version of 8.5.
+    are resolved by time-out when we exceed <varname>max_standby_delay</>.
    </para>
 
    <para>
@@ -2630,11 +2626,7 @@ LOG:  database system is ready to accept read only connections
     <varname>max_standby_delay</> or even set it to zero, though that is a
     very aggressive setting. If the standby server is tasked as an additional
     server for decision support queries then it may be acceptable to set this
-    to a value of many hours (in seconds).  It is also possible to set
-    <varname>max_standby_delay</> to -1 which means wait forever for queries
-    to complete, if there are conflicts; this will be useful when performing
-    an archive recovery from a backup.
-   </para>
+    to a value of many hours (in seconds).
 
    <para>
     Transaction status "hint bits" written on primary are not WAL-logged,
index 0366775..4a68199 100644 (file)
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.244 2010/01/15 09:18:58 heikki Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.245 2010/01/23 16:37:12 sriggs Exp $ -->
 
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -1825,14 +1825,15 @@ archive_command = 'copy "%p" "C:\\server\\archivedir\\%f"'  # Windows
       <listitem>
        <para>
         When server acts as a standby, this parameter specifies a wait policy
-        for queries that conflict with incoming data changes. Valid settings
-        are -1, meaning wait forever, or a wait time of 0 or more seconds.
-        If a conflict should occur the server will delay up to this
-        amount before it begins trying to resolve things less amicably, as
+        for queries that conflict with data changes being replayed by recovery.
+        If a conflict should occur the server will delay up to this number
+        of seconds before it begins trying to resolve things less amicably, as
         described in <xref linkend="hot-standby-conflict">. Typically,
         this parameter makes sense only during replication, so when
-        performing an archive recovery to recover from data loss a
-        parameter setting of 0 is recommended.  The default is 30 seconds.
+        performing an archive recovery to recover from data loss a very high
+        parameter setting is recommended.  The default is 30 seconds.
+        There is no wait-forever setting because of the potential for deadlock
+        which that setting would introduce.
         This parameter can only be set in the <filename>postgresql.conf</>
         file or on the server command line.
        </para>
index a7ff66a..004ea0a 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.359 2010/01/20 19:43:40 heikki Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.360 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -8803,9 +8803,12 @@ StartupProcessMain(void)
         */
        pqsignal(SIGHUP, StartupProcSigHupHandler); /* reload config file */
        pqsignal(SIGINT, SIG_IGN);      /* ignore query cancel */
-       pqsignal(SIGTERM, StartupProcShutdownHandler);          /* request shutdown */
-       pqsignal(SIGQUIT, startupproc_quickdie);        /* hard crash time */
-       pqsignal(SIGALRM, SIG_IGN);
+       pqsignal(SIGTERM, StartupProcShutdownHandler);  /* request shutdown */
+       pqsignal(SIGQUIT, startupproc_quickdie);                /* hard crash time */
+       if (XLogRequestRecoveryConnections)
+               pqsignal(SIGALRM, handle_standby_sig_alarm); /* ignored unless InHotStandby */
+       else
+               pqsignal(SIGALRM, SIG_IGN);
        pqsignal(SIGPIPE, SIG_IGN);
        pqsignal(SIGUSR1, SIG_IGN);
        pqsignal(SIGUSR2, SIG_IGN);
index 77f35fd..470800d 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.254 2010/01/02 16:57:51 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.255 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -44,6 +44,7 @@
 #include "storage/ipc.h"
 #include "storage/proc.h"
 #include "storage/smgr.h"
+#include "storage/standby.h"
 #include "utils/rel.h"
 #include "utils/resowner.h"
 
@@ -2417,14 +2418,49 @@ LockBufferForCleanup(Buffer buffer)
                PinCountWaitBuf = bufHdr;
                UnlockBufHdr(bufHdr);
                LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
+
                /* Wait to be signaled by UnpinBuffer() */
-               ProcWaitForSignal();
+               if (InHotStandby)
+               {
+                       /* Share the bufid that Startup process waits on */
+                       SetStartupBufferPinWaitBufId(buffer - 1);
+                       /* Set alarm and then wait to be signaled by UnpinBuffer() */
+                       ResolveRecoveryConflictWithBufferPin();
+                       SetStartupBufferPinWaitBufId(-1);
+               }
+               else
+                       ProcWaitForSignal();
+
                PinCountWaitBuf = NULL;
                /* Loop back and try again */
        }
 }
 
 /*
+ * Check called from RecoveryConflictInterrupt handler when Startup
+ * process requests cancelation of all pin holders that are blocking it.
+ */
+bool
+HoldingBufferPinThatDelaysRecovery(void)
+{
+       int             bufid = GetStartupBufferPinWaitBufId();
+
+       /*
+        * If we get woken slowly then it's possible that the Startup process
+        * was already woken by other backends before we got here. Also possible
+        * that we get here by multiple interrupts or interrupts at inappropriate
+        * times, so make sure we do nothing if the bufid is not set.
+        */
+       if (bufid < 0)
+               return false;
+
+       if (PrivateRefCount[bufid] > 0)
+               return true;
+
+       return false;
+}
+
+/*
  * ConditionalLockBufferForCleanup - as above, but don't wait to get the lock
  *
  * We won't loop, but just check once to see if the pin count is OK.  If
index 1793783..7cd57f3 100644 (file)
@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.58 2010/01/21 00:53:58 sriggs Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.59 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1680,15 +1680,13 @@ GetCurrentVirtualXIDs(TransactionId limitXmin, bool excludeXmin0,
  * latestCompletedXid since doing so would be a performance issue during
  * normal running, so we check it essentially for free on the standby.
  *
- * If dbOid is valid we skip backends attached to other databases. Some
- * callers choose to skipExistingConflicts.
+ * If dbOid is valid we skip backends attached to other databases.
  *
  * Be careful to *not* pfree the result from this function. We reuse
  * this array sufficiently often that we use malloc for the result.
  */
 VirtualTransactionId *
-GetConflictingVirtualXIDs(TransactionId limitXmin, Oid dbOid,
-                                                 bool skipExistingConflicts)
+GetConflictingVirtualXIDs(TransactionId limitXmin, Oid dbOid)
 {
        static VirtualTransactionId *vxids;
        ProcArrayStruct *arrayP = procArray;
@@ -1727,9 +1725,6 @@ GetConflictingVirtualXIDs(TransactionId limitXmin, Oid dbOid,
                if (proc->pid == 0)
                        continue;
 
-               if (skipExistingConflicts && proc->recoveryConflictPending)
-                       continue;
-
                if (!OidIsValid(dbOid) ||
                        proc->databaseId == dbOid)
                {
@@ -1886,7 +1881,7 @@ CountDBBackends(Oid databaseid)
  * CancelDBBackends --- cancel backends that are using specified database
  */
 void
-CancelDBBackends(Oid databaseid)
+CancelDBBackends(Oid databaseid, ProcSignalReason sigmode, bool conflictPending)
 {
        ProcArrayStruct *arrayP = procArray;
        int                     index;
@@ -1899,13 +1894,13 @@ CancelDBBackends(Oid databaseid)
        {
                volatile PGPROC *proc = arrayP->procs[index];
 
-               if (proc->databaseId == databaseid)
+               if (databaseid == InvalidOid || proc->databaseId == databaseid)
                {
                        VirtualTransactionId procvxid;
 
                        GET_VXID_FROM_PGPROC(procvxid, *proc);
 
-                       proc->recoveryConflictPending = true;
+                       proc->recoveryConflictPending = conflictPending;
                        pid = proc->pid;
                        if (pid != 0)
                        {
@@ -1913,8 +1908,7 @@ CancelDBBackends(Oid databaseid)
                                 * Kill the pid if it's still here. If not, that's what we wanted
                                 * so ignore any errors.
                                 */
-                               (void) SendProcSignal(pid, PROCSIG_RECOVERY_CONFLICT_DATABASE,
-                                                                               procvxid.backendId);
+                               (void) SendProcSignal(pid, sigmode, procvxid.backendId);
                        }
                }
        }
index 453d94a..6c38d42 100644 (file)
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/ipc/procsignal.c,v 1.3 2010/01/16 10:05:50 sriggs Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/ipc/procsignal.c,v 1.4 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -272,5 +272,8 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
        if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT))
                RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_SNAPSHOT);
 
+       if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))
+               RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
+
        errno = save_errno;
 }
index dcead94..f079dba 100644 (file)
@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/ipc/standby.c,v 1.6 2010/01/16 10:13:04 sriggs Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/ipc/standby.c,v 1.7 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -126,10 +126,6 @@ WaitExceedsMaxStandbyDelay(void)
        long    delay_secs;
        int             delay_usecs;
 
-       /* max_standby_delay = -1 means wait forever, if necessary */
-       if (MaxStandbyDelay < 0)
-               return false;
-
        /* Are we past max_standby_delay? */
        TimestampDifference(GetLatestXLogTime(), GetCurrentTimestamp(),
                                                &delay_secs, &delay_usecs);
@@ -241,8 +237,7 @@ ResolveRecoveryConflictWithSnapshot(TransactionId latestRemovedXid)
        VirtualTransactionId *backends;
 
        backends = GetConflictingVirtualXIDs(latestRemovedXid,
-                                                                                InvalidOid,
-                                                                                true);
+                                                                                InvalidOid);
 
        ResolveRecoveryConflictWithVirtualXIDs(backends,
                                                                                   PROCSIG_RECOVERY_CONFLICT_SNAPSHOT);
@@ -273,8 +268,7 @@ ResolveRecoveryConflictWithTablespace(Oid tsid)
         * non-transactional.
         */
        temp_file_users = GetConflictingVirtualXIDs(InvalidTransactionId,
-                                                                                               InvalidOid,
-                                                                                               false);
+                                                                                               InvalidOid);
        ResolveRecoveryConflictWithVirtualXIDs(temp_file_users,
                                                                                   PROCSIG_RECOVERY_CONFLICT_TABLESPACE);
 }
@@ -295,7 +289,7 @@ ResolveRecoveryConflictWithDatabase(Oid dbid)
         */
        while (CountDBBackends(dbid) > 0)
        {
-               CancelDBBackends(dbid);
+               CancelDBBackends(dbid, PROCSIG_RECOVERY_CONFLICT_TABLESPACE, true);
 
                /*
                 * Wait awhile for them to die so that we avoid flooding an
@@ -331,8 +325,7 @@ ResolveRecoveryConflictWithLock(Oid dbOid, Oid relOid)
                else
                {
                        backends = GetConflictingVirtualXIDs(InvalidTransactionId,
-                                                                                                InvalidOid,
-                                                                                                true);
+                                                                                                InvalidOid);
                        report_memory_error = true;
                }
 
@@ -346,6 +339,113 @@ ResolveRecoveryConflictWithLock(Oid dbOid, Oid relOid)
 }
 
 /*
+ * ResolveRecoveryConflictWithBufferPin is called from LockBufferForCleanup()
+ * to resolve conflicts with other backends holding buffer pins.
+ *
+ * We either resolve conflicts immediately or set a SIGALRM to wake us at
+ * the limit of our patience. The sleep in LockBufferForCleanup() is
+ * performed here, for code clarity.
+ *
+ * Resolve conflict by sending a SIGUSR1 reason to all backends to check if
+ * 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
+ * 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.
+ */
+void
+ResolveRecoveryConflictWithBufferPin(void)
+{
+       bool    sig_alarm_enabled = false;
+
+       Assert(InHotStandby);
+
+       /*
+        * Signal immediately or set alarm for later.
+        */
+       if (MaxStandbyDelay == 0)
+               SendRecoveryConflictWithBufferPin();
+       else
+       {
+               TimestampTz now;
+               long    standby_delay_secs;             /* How far Startup process is lagging */
+               int             standby_delay_usecs;
+
+               now = GetCurrentTimestamp();
+
+               /* Are we past max_standby_delay? */
+               TimestampDifference(GetLatestXLogTime(), now,
+                                                       &standby_delay_secs, &standby_delay_usecs);
+
+               if (standby_delay_secs >= (long) MaxStandbyDelay)
+                       SendRecoveryConflictWithBufferPin();
+               else
+               {
+                       TimestampTz fin_time;                   /* Expected wake-up time by timer */
+                       long    timer_delay_secs;               /* Amount of time we set timer for */
+                       int             timer_delay_usecs = 0;
+
+                       /*
+                        * How much longer we should wait?
+                        */
+                       timer_delay_secs = MaxStandbyDelay - standby_delay_secs;
+                       if (standby_delay_usecs > 0)
+                       {
+                               timer_delay_secs -= 1;
+                               timer_delay_usecs = 1000000 - standby_delay_usecs;
+                       }
+
+                       /*
+                        * It's possible that the difference is less than a microsecond;
+                        * ensure we don't cancel, rather than set, the interrupt.
+                        */
+                       if (timer_delay_secs == 0 && timer_delay_usecs == 0)
+                               timer_delay_usecs = 1;
+
+                       /*
+                        * When is the finish time? We recheck this if we are woken early.
+                        */
+                       fin_time = TimestampTzPlusMilliseconds(now,
+                                                                                                       (timer_delay_secs * 1000) +
+                                                                                                       (timer_delay_usecs / 1000));
+
+                       if (enable_standby_sig_alarm(timer_delay_secs, timer_delay_usecs, fin_time))
+                               sig_alarm_enabled = true;
+                       else
+                               elog(FATAL, "could not set timer for process wakeup");
+               }
+       }
+
+       /* Wait to be signaled by UnpinBuffer() */
+       ProcWaitForSignal();
+
+       if (sig_alarm_enabled)
+       {
+               if (!disable_standby_sig_alarm())
+                       elog(FATAL, "could not disable timer for process wakeup");
+       }
+}
+
+void
+SendRecoveryConflictWithBufferPin(void)
+{
+       /*
+        * 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);
+}
+
+/*
  * -----------------------------------------------------
  * Locking in Recovery Mode
  * -----------------------------------------------------
index 74fbcbd..ea781a8 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.190 2010/01/02 16:57:52 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.191 2010/01/23 16:37:12 sriggs Exp $
  *
  * NOTES
  *       A lock table is a shared memory hash table.  When
@@ -815,25 +815,6 @@ LockAcquireExtended(const LOCKTAG *locktag,
                }
 
                /*
-                * In Hot Standby we abort the lock wait if Startup process is waiting
-                * since this would result in a deadlock. The deadlock occurs because
-                * if we are waiting it must be behind an AccessExclusiveLock, which
-                * can only clear when a transaction completion record is replayed.
-                * If Startup process is waiting we never will clear that lock, so to
-                * wait for it just causes a deadlock.
-                */
-               if (RecoveryInProgress() && !InRecovery &&
-                       locktag->locktag_type == LOCKTAG_RELATION)
-               {
-                       LWLockRelease(partitionLock);
-                       ereport(ERROR,
-                                       (errcode(ERRCODE_T_R_DEADLOCK_DETECTED),
-                                        errmsg("possible deadlock detected"),
-                                        errdetail("process conflicts with recovery - please resubmit query later"),
-                                        errdetail_log("process conflicts with recovery")));
-               }
-
-               /*
                 * Set bitmask of locks this process already holds on this object.
                 */
                MyProc->heldLocks = proclock->holdMask;
index ac89182..da64e19 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.213 2010/01/16 10:05:50 sriggs Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.214 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -73,6 +73,7 @@ NON_EXEC_STATIC PGPROC *AuxiliaryProcs = NULL;
 static LOCALLOCK *lockAwaited = NULL;
 
 /* Mark these volatile because they can be changed by signal handler */
+static volatile bool standby_timeout_active = false;
 static volatile bool statement_timeout_active = false;
 static volatile bool deadlock_timeout_active = false;
 static volatile DeadLockState deadlock_state = DS_NOT_YET_CHECKED;
@@ -89,6 +90,7 @@ static void RemoveProcFromArray(int code, Datum arg);
 static void ProcKill(int code, Datum arg);
 static void AuxiliaryProcKill(int code, Datum arg);
 static bool CheckStatementTimeout(void);
+static bool CheckStandbyTimeout(void);
 
 
 /*
@@ -107,6 +109,8 @@ ProcGlobalShmemSize(void)
        size = add_size(size, mul_size(MaxBackends, sizeof(PGPROC)));
        /* ProcStructLock */
        size = add_size(size, sizeof(slock_t));
+       /* startupBufferPinWaitBufId */
+       size = add_size(size, sizeof(NBuffers));
 
        return size;
 }
@@ -487,11 +491,44 @@ PublishStartupProcessInformation(void)
 
        procglobal->startupProc = MyProc;
        procglobal->startupProcPid = MyProcPid;
+       procglobal->startupBufferPinWaitBufId = 0;
 
        SpinLockRelease(ProcStructLock);
 }
 
 /*
+ * Used from bufgr to share the value of the buffer that Startup waits on,
+ * or to reset the value to "not waiting" (-1). This allows processing
+ * of recovery conflicts for buffer pins. Set is made before backends look
+ * at this value, so locking not required, especially since the set is
+ * an atomic integer set operation.
+ */
+void
+SetStartupBufferPinWaitBufId(int bufid)
+{
+       /* use volatile pointer to prevent code rearrangement */
+       volatile PROC_HDR *procglobal = ProcGlobal;
+
+       procglobal->startupBufferPinWaitBufId = bufid;
+}
+
+/*
+ * Used by backends when they receive a request to check for buffer pin waits.
+ */
+int
+GetStartupBufferPinWaitBufId(void)
+{
+       int bufid;
+
+       /* use volatile pointer to prevent code rearrangement */
+       volatile PROC_HDR *procglobal = ProcGlobal;
+
+       bufid = procglobal->startupBufferPinWaitBufId;
+
+       return bufid;
+}
+
+/*
  * Check whether there are at least N free PGPROC objects.
  *
  * Note: this is designed on the assumption that N will generally be small.
@@ -1542,7 +1579,7 @@ CheckStatementTimeout(void)
 
 
 /*
- * Signal handler for SIGALRM
+ * Signal handler for SIGALRM for normal user backends
  *
  * Process deadlock check and/or statement timeout check, as needed.
  * To avoid various edge cases, we must be careful to do nothing
@@ -1565,3 +1602,112 @@ handle_sig_alarm(SIGNAL_ARGS)
 
        errno = save_errno;
 }
+
+/*
+ * Signal handler for SIGALRM in Startup process
+ *
+ * To avoid various edge cases, we must be careful to do nothing
+ * when there is nothing to be done.  We also need to be able to
+ * reschedule the timer interrupt if called before end of statement.
+ */
+bool
+enable_standby_sig_alarm(long delay_s, int delay_us, TimestampTz fin_time)
+{
+       struct itimerval timeval;
+
+       Assert(delay_s >= 0 && delay_us >= 0);
+
+       statement_fin_time = fin_time;
+
+       standby_timeout_active = true;
+
+       MemSet(&timeval, 0, sizeof(struct itimerval));
+       timeval.it_value.tv_sec = delay_s;
+       timeval.it_value.tv_usec = delay_us;
+       if (setitimer(ITIMER_REAL, &timeval, NULL))
+               return false;
+       return true;
+}
+
+bool
+disable_standby_sig_alarm(void)
+{
+       /*
+        * Always disable the interrupt if it is active; this avoids being
+        * interrupted by the signal handler and thereby possibly getting
+        * confused.
+        *
+        * We will re-enable the interrupt if necessary in CheckStandbyTimeout.
+        */
+       if (standby_timeout_active)
+       {
+               struct itimerval timeval;
+
+               MemSet(&timeval, 0, sizeof(struct itimerval));
+               if (setitimer(ITIMER_REAL, &timeval, NULL))
+               {
+                       standby_timeout_active = false;
+                       return false;
+               }
+       }
+
+       standby_timeout_active = false;
+
+       return true;
+}
+
+/*
+ * CheckStandbyTimeout() runs unconditionally in the Startup process
+ * SIGALRM handler. Timers will only be set when InHotStandby.
+ * We simply ignore any signals unless the timer has been set.
+ */
+static bool
+CheckStandbyTimeout(void)
+{
+       TimestampTz now;
+
+       standby_timeout_active = false;
+
+       now = GetCurrentTimestamp();
+
+       if (now >= statement_fin_time)
+               SendRecoveryConflictWithBufferPin();
+       else
+       {
+               /* Not time yet, so (re)schedule the interrupt */
+               long            secs;
+               int                     usecs;
+               struct itimerval timeval;
+
+               TimestampDifference(now, statement_fin_time,
+                                                       &secs, &usecs);
+
+               /*
+                * It's possible that the difference is less than a microsecond;
+                * ensure we don't cancel, rather than set, the interrupt.
+                */
+               if (secs == 0 && usecs == 0)
+                       usecs = 1;
+
+               standby_timeout_active = true;
+
+               MemSet(&timeval, 0, sizeof(struct itimerval));
+               timeval.it_value.tv_sec = secs;
+               timeval.it_value.tv_usec = usecs;
+               if (setitimer(ITIMER_REAL, &timeval, NULL))
+                       return false;
+       }
+
+       return true;
+}
+
+void
+handle_standby_sig_alarm(SIGNAL_ARGS)
+{
+       int save_errno = errno;
+
+       if (standby_timeout_active)
+               (void) CheckStandbyTimeout();
+
+       errno = save_errno;
+}
index e034a4e..86d9e3c 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.585 2010/01/21 09:30:36 sriggs Exp $
+ *       $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.586 2010/01/23 16:37:12 sriggs Exp $
  *
  * NOTES
  *       this is the "main" module of the postgres backend and
@@ -2718,6 +2718,18 @@ RecoveryConflictInterrupt(ProcSignalReason reason)
        {
                switch (reason)
                {
+                       case PROCSIG_RECOVERY_CONFLICT_BUFFERPIN:
+                                       /*
+                                        * If we aren't blocking the Startup process there is
+                                        * nothing more to do.
+                                        */
+                                       if (!HoldingBufferPinThatDelaysRecovery())
+                                               return;
+
+                                       MyProc->recoveryConflictPending = true;
+
+                                       /* Intentional drop through to error handling */
+
                        case PROCSIG_RECOVERY_CONFLICT_LOCK:
                        case PROCSIG_RECOVERY_CONFLICT_TABLESPACE:
                        case PROCSIG_RECOVERY_CONFLICT_SNAPSHOT:
index 2740301..6846d13 100644 (file)
@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.533 2010/01/15 09:19:04 heikki Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.534 2010/01/23 16:37:12 sriggs Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -1383,7 +1383,7 @@ static struct config_int ConfigureNamesInt[] =
                        NULL
                },
                &MaxStandbyDelay,
-               30, -1, INT_MAX, NULL, NULL
+               30, 0, INT_MAX, NULL, NULL
        },
 
        {
index e8e2aba..dc4376e 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.123 2010/01/02 16:58:08 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.124 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -198,6 +198,7 @@ extern void LockBuffer(Buffer buffer, int mode);
 extern bool ConditionalLockBuffer(Buffer buffer);
 extern void LockBufferForCleanup(Buffer buffer);
 extern bool ConditionalLockBufferForCleanup(Buffer buffer);
+extern bool HoldingBufferPinThatDelaysRecovery(void);
 
 extern void AbortBufferIO(void);
 
index 5050090..5a4421b 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.118 2010/01/16 10:05:50 sriggs Exp $
+ * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.119 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,7 +16,7 @@
 
 #include "storage/lock.h"
 #include "storage/pg_sema.h"
-
+#include "utils/timestamp.h"
 
 /*
  * Each backend advertises up to PGPROC_MAX_CACHED_SUBXIDS TransactionIds
@@ -145,6 +145,8 @@ typedef struct PROC_HDR
        /* The proc of the Startup process, since not in ProcArray */
        PGPROC     *startupProc;
        int                     startupProcPid;
+       /* Buffer id of the buffer that Startup process waits for pin on */
+       int                     startupBufferPinWaitBufId;
 } PROC_HDR;
 
 /*
@@ -177,6 +179,8 @@ extern void InitProcessPhase2(void);
 extern void InitAuxiliaryProcess(void);
 
 extern void PublishStartupProcessInformation(void);
+extern void SetStartupBufferPinWaitBufId(int bufid);
+extern int GetStartupBufferPinWaitBufId(void);
 
 extern bool HaveNFreeProcs(int n);
 extern void ProcReleaseLocks(bool isCommit);
@@ -194,4 +198,8 @@ extern bool enable_sig_alarm(int delayms, bool is_statement_timeout);
 extern bool disable_sig_alarm(bool is_statement_timeout);
 extern void handle_sig_alarm(SIGNAL_ARGS);
 
+extern bool enable_standby_sig_alarm(long delay_s, int delay_us, TimestampTz fin_time);
+extern bool disable_standby_sig_alarm(void);
+extern void handle_standby_sig_alarm(SIGNAL_ARGS);
+
 #endif   /* PROC_H */
index 42953b0..ed68be6 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/procarray.h,v 1.30 2010/01/16 10:05:56 sriggs Exp $
+ * $PostgreSQL: pgsql/src/include/storage/procarray.h,v 1.31 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -57,13 +57,12 @@ extern bool IsBackendPid(int pid);
 extern VirtualTransactionId *GetCurrentVirtualXIDs(TransactionId limitXmin,
                                          bool excludeXmin0, bool allDbs, int excludeVacuum,
                                          int *nvxids);
-extern VirtualTransactionId *GetConflictingVirtualXIDs(TransactionId limitXmin,
-                                       Oid dbOid, bool skipExistingConflicts);
+extern VirtualTransactionId *GetConflictingVirtualXIDs(TransactionId limitXmin, Oid dbOid);
 extern pid_t CancelVirtualTransaction(VirtualTransactionId vxid, ProcSignalReason sigmode);
 
 extern int     CountActiveBackends(void);
 extern int     CountDBBackends(Oid databaseid);
-extern void    CancelDBBackends(Oid databaseid);
+extern void CancelDBBackends(Oid databaseid, ProcSignalReason sigmode, bool conflictPending);
 extern int     CountUserBackends(Oid roleid);
 extern bool CountOtherDBBackends(Oid databaseId,
                                         int *nbackends, int *nprepared);
index cbe0e24..2a67a62 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/procsignal.h,v 1.3 2010/01/16 10:05:57 sriggs Exp $
+ * $PostgreSQL: pgsql/src/include/storage/procsignal.h,v 1.4 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -37,6 +37,7 @@ typedef enum
        PROCSIG_RECOVERY_CONFLICT_TABLESPACE,
        PROCSIG_RECOVERY_CONFLICT_LOCK,
        PROCSIG_RECOVERY_CONFLICT_SNAPSHOT,
+       PROCSIG_RECOVERY_CONFLICT_BUFFERPIN,
 
        NUM_PROCSIGNALS                         /* Must be last! */
 } ProcSignalReason;
index 8c982cf..e127980 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/standby.h,v 1.4 2010/01/16 10:05:57 sriggs Exp $
+ * $PostgreSQL: pgsql/src/include/storage/standby.h,v 1.5 2010/01/23 16:37:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
 
 extern int     vacuum_defer_cleanup_age;
 
+extern void InitRecoveryTransactionEnvironment(void);
+extern void ShutdownRecoveryTransactionEnvironment(void);
+
 extern void ResolveRecoveryConflictWithSnapshot(TransactionId latestRemovedXid);
 extern void ResolveRecoveryConflictWithTablespace(Oid tsid);
 extern void ResolveRecoveryConflictWithDatabase(Oid dbid);
 
-extern void InitRecoveryTransactionEnvironment(void);
-extern void ShutdownRecoveryTransactionEnvironment(void);
+extern void ResolveRecoveryConflictWithBufferPin(void);
+extern void SendRecoveryConflictWithBufferPin(void);
 
 /*
  * Standby Rmgr (RM_STANDBY_ID)