Avoid crash in interrupted autovacuum worker, caused by leaving the current

memory context pointing at a context not long lived enough.

Also, create a fake PortalContext where to store the vac_context, if only
to avoid having it be a top-level memory context.

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 2739e2484fd0dd1ef0f8539bb101473b0d5546d4..e1fff7e6f8c487427b094b12bb94a6a088f28316 100644 (file)
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -55,7 +55,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.52 2007/06/29 17:07:39 alvherre Exp $
+ *       $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.53 2007/06/30 04:08:05 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1427,8 +1427,8 @@ AutoVacWorkerMain(int argc, char *argv[])
        pqsignal(SIGHUP, SIG_IGN);
 
        /*
-        * Presently, SIGINT will lead to autovacuum shutdown, because that's how
-        * we handle ereport(ERROR).  It could be improved however.
+        * SIGINT is used to signal cancelling the current table's vacuum;
+        * SIGTERM means abort and exit cleanly, and SIGQUIT means abandon ship.
         */
        pqsignal(SIGINT, StatementCancelHandler);
        pqsignal(SIGTERM, die);
@@ -1513,6 +1513,7 @@ AutoVacWorkerMain(int argc, char *argv[])
                /* insert into the running list */
                SHMQueueInsertBefore(&AutoVacuumShmem->av_runningWorkers, 
                                                         &MyWorkerInfo->wi_links);
+
                /*
                 * remove from the "starting" pointer, so that the launcher can start
                 * a new worker if required
@@ -1560,13 +1561,6 @@ AutoVacWorkerMain(int argc, char *argv[])
                ereport(DEBUG1,
                                (errmsg("autovacuum: processing database \"%s\"", dbname)));
 
-               /* Create the memory context where cross-transaction state is stored */
-               AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
-                                                                                         "AV worker",
-                                                                                         ALLOCSET_DEFAULT_MINSIZE,
-                                                                                         ALLOCSET_DEFAULT_INITSIZE,
-                                                                                         ALLOCSET_DEFAULT_MAXSIZE);
-
                /* And do an appropriate amount of work */
                recentXid = ReadNewTransactionId();
                do_autovacuum();
@@ -1787,6 +1781,18 @@ do_autovacuum(void)
        PgStat_StatDBEntry *dbentry;
        BufferAccessStrategy bstrategy;
 
+       /*
+        * StartTransactionCommand and CommitTransactionCommand will automatically
+        * switch to other contexts.  We need this one to keep the list of
+        * relations to vacuum/analyze across transactions.
+        */
+       AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
+                                                                                 "AV worker",
+                                                                                 ALLOCSET_DEFAULT_MINSIZE,
+                                                                                 ALLOCSET_DEFAULT_INITSIZE,
+                                                                                 ALLOCSET_DEFAULT_MAXSIZE);
+       MemoryContextSwitchTo(AutovacMemCxt);
+
        /*
         * may be NULL if we couldn't find an entry (only happens if we
         * are forcing a vacuum for anti-wrap purposes).
@@ -1825,11 +1831,7 @@ do_autovacuum(void)
 
        ReleaseSysCache(tuple);
 
-       /*
-        * StartTransactionCommand and CommitTransactionCommand will automatically
-        * switch to other contexts.  We need this one to keep the list of
-        * relations to vacuum/analyze across transactions.
-        */
+       /* StartTransactionCommand changed elsewhere */
        MemoryContextSwitchTo(AutovacMemCxt);
 
        /* The database hash where pgstat keeps shared relations */
@@ -1932,6 +1934,16 @@ do_autovacuum(void)
         */
        bstrategy = GetAccessStrategy(BAS_VACUUM);
 
+       /*
+        * create a memory context to act as fake PortalContext, so that the
+        * contexts created in the vacuum code are cleaned up for each table.
+        */
+       PortalContext = AllocSetContextCreate(AutovacMemCxt,
+                                                                                 "Autovacuum Portal",
+                                                                                 ALLOCSET_DEFAULT_INITSIZE,
+                                                                                 ALLOCSET_DEFAULT_MINSIZE,
+                                                                                 ALLOCSET_DEFAULT_MAXSIZE);
+
        /*
         * Perform operations on collected tables.
         */
@@ -1996,6 +2008,7 @@ next_worker:
                 * FIXME we ignore the possibility that the table was finished being
                 * vacuumed in the last 500ms (PGSTAT_STAT_INTERVAL).  This is a bug.
                 */
+               MemoryContextSwitchTo(AutovacMemCxt);
                tab = table_recheck_autovac(relid);
                if (tab == NULL)
                {
@@ -2026,6 +2039,9 @@ next_worker:
                autovac_balance_cost();
                LWLockRelease(AutovacuumLock);
 
+               /* clean up memory before each iteration */
+               MemoryContextResetAndDeleteChildren(PortalContext);
+
                /*
                 * We will abort vacuuming the current table if we are interrupted, and
                 * continue with the next one in schedule; but if anything else
@@ -2035,6 +2051,7 @@ next_worker:
                PG_TRY();
                {
                        /* have at it */
+                       MemoryContextSwitchTo(TopTransactionContext);
                        autovacuum_do_vac_analyze(tab->at_relid,
                                                                          tab->at_dovacuum,
                                                                          tab->at_doanalyze,
@@ -2063,6 +2080,7 @@ next_worker:
 
                                AbortOutOfAnyTransaction();
                                FlushErrorState();
+                               MemoryContextResetAndDeleteChildren(PortalContext);
 
                                /* restart our transaction for the following operations */
                                StartTransactionCommand();