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();