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 */