Honour shared queue refcount while deciding to remove it from hash table when

producer unbinds

It's possible that another execution of the portal may start just while we are
unbinding. Hence premature removal of the shared queue should be avoided.

diff --git a/src/backend/pgxc/squeue/squeue.c b/src/backend/pgxc/squeue/squeue.c
index 0d2844aa5c9e7ad5ca0410f828d6324e5cd097db..a93857114707285f2c35fc399b7df9a9151751bc 100644 (file)
--- a/src/backend/pgxc/squeue/squeue.c
+++ b/src/backend/pgxc/squeue/squeue.c
@@ -1448,23 +1448,17 @@ CHECK:
                goto CHECK;
        }
 
-       /*
-        * XXX Decrement the refcnt, but it doesn't really matter because we are
-        * unconditionally removing the SQueue anyways. SharedQueueRelease is
-        * prepared to work with already removed SQueue
-        *
-        * This ought to be fixed someday
-        */
-       squeue->sq_refcnt--;
-       
        /* All is done, clean up */
        DisownLatch(&sqsync->sqs_producer_latch);
 
-       /* Now it is OK to remove hash table entry */
-       squeue->sq_sync = NULL;
-       sqsync->queue = NULL;
-       if (hash_search(SharedQueues, squeue->sq_key, HASH_REMOVE, NULL) != squeue)
-               elog(PANIC, "Shared queue data corruption");
+       if (--squeue->sq_refcnt == 0)
+       {
+               /* Now it is OK to remove hash table entry */
+               squeue->sq_sync = NULL;
+               sqsync->queue = NULL;
+               if (hash_search(SharedQueues, squeue->sq_key, HASH_REMOVE, NULL) != squeue)
+                       elog(PANIC, "Shared queue data corruption");
+       }
 
        LWLockRelease(SQueuesLock);
 }