Fix failure to check for INVALID worker entry in the new autovacuum code, which

could happen when a worker took to long to start and was thus "aborted" by the
launcher.  Noticed by lionfish buildfarm member.

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index d5bb99c504ba01af072288ca1a66b84c402fa760..59128212d5ae02a539dd5ad2b8aaed04083f0fc7 100644 (file)
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.42 2007/04/18 16:44:18 alvherre Exp $
+ *       $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.43 2007/05/02 15:47:14 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1407,25 +1407,36 @@ AutoVacWorkerMain(int argc, char *argv[])
         * Get the info about the database we're going to work on.
         */
        LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
-       MyWorkerInfo = (WorkerInfo) MAKE_PTR(AutoVacuumShmem->av_startingWorker);
-       dbid = MyWorkerInfo->wi_dboid;
-       MyWorkerInfo->wi_workerpid = MyProcPid;
 
-       /* 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
+        * beware of startingWorker being INVALID; this could happen if the
+        * launcher thinks we've taking too long to start.
         */
-       AutoVacuumShmem->av_startingWorker = INVALID_OFFSET;
-       LWLockRelease(AutovacuumLock);
+       if (AutoVacuumShmem->av_startingWorker != INVALID_OFFSET)
+       {
+               MyWorkerInfo = (WorkerInfo) MAKE_PTR(AutoVacuumShmem->av_startingWorker);
+               dbid = MyWorkerInfo->wi_dboid;
+               MyWorkerInfo->wi_workerpid = MyProcPid;
+
+               /* 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
+                */
+               AutoVacuumShmem->av_startingWorker = INVALID_OFFSET;
+               LWLockRelease(AutovacuumLock);
 
-       on_shmem_exit(FreeWorkerInfo, 0);
+               on_shmem_exit(FreeWorkerInfo, 0);
 
-       /* wake up the launcher */
-       if (AutoVacuumShmem->av_launcherpid != 0)
-               kill(AutoVacuumShmem->av_launcherpid, SIGUSR1);
+               /* wake up the launcher */
+               if (AutoVacuumShmem->av_launcherpid != 0)
+                       kill(AutoVacuumShmem->av_launcherpid, SIGUSR1);
+       }
+       else
+               /* no worker entry for me, go away */
+               LWLockRelease(AutovacuumLock);
 
        if (OidIsValid(dbid))
        {
@@ -1466,8 +1477,8 @@ AutoVacWorkerMain(int argc, char *argv[])
        }
 
        /*
-        * FIXME -- we need to notify the launcher when we are gone.  But this
-        * should be done after our PGPROC is released, in ProcKill.
+        * The launcher will be notified of my death in ProcKill, *if* we managed
+        * to get a worker slot at all
         */
 
        /* All done, go away */