Avoid server crash when worker registration fails at execution time.

robertmhaas · robertmhaas · commit 6c878a755368 · 2015-11-20T13:03:39.000-05:00
The previous coding attempts to destroy the DSM in this case, but
child nodes might have stored data there and still be holding onto
pointers in this case.  So don't do that.

Also, free the reader array instead of leaking it.

Extracted from two different patch versions both by Amit Kapila.
diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c
@@ -190,7 +190,7 @@ ExecGather(GatherState *node)
 
 			/* No workers?  Then never mind. */
 			if (!got_any_worker)
-				ExecShutdownGather(node);
+				ExecShutdownGatherWorkers(node);
 		}
 
 		/* Run plan locally if no workers or not single-copy. */
@@ -402,6 +402,8 @@ ExecShutdownGatherWorkers(GatherState *node)
 
 		for (i = 0; i < node->nreaders; ++i)
 			DestroyTupleQueueReader(node->reader[i]);
+
+		pfree(node->reader);
 		node->reader = NULL;
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -190,7 +190,7 @@ ExecGather(GatherState *node)`
`190`	`190`
`191`	`191`	`/* No workers? Then never mind. */`
`192`	`192`	`if (!got_any_worker)`
`193`		`- ExecShutdownGather(node);`
	`193`	`+ ExecShutdownGatherWorkers(node);`
`194`	`194`	`}`
`195`	`195`
`196`	`196`	`/* Run plan locally if no workers or not single-copy. */`
`@@ -402,6 +402,8 @@ ExecShutdownGatherWorkers(GatherState *node)`
`402`	`402`
`403`	`403`	`for (i = 0; i < node->nreaders; ++i)`
`404`	`404`	`DestroyTupleQueueReader(node->reader[i]);`
	`405`	`+`
	`406`	`+ pfree(node->reader);`
`405`	`407`	`node->reader = NULL;`
`406`	`408`	`}`
`407`	`409`