From bfb937427be2cfca78e3e076c30e37cddc350f8e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 16 Jun 2016 15:20:29 -0400
Subject: [PATCH] Fix fuzzy thinking in ReinitializeParallelDSM().
The fact that no workers were successfully launched in the previous
iteration does not excuse us from setting up properly to try again.
This appears to explain crashes I saw in parallel regression testing
due to error_mqh being NULL when it shouldn't be.
Minor other cosmetic fixes too.
---
src/backend/access/transam/parallel.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index ab5ef2573cf..9325b628da3 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -191,8 +191,8 @@ CreateParallelContextForExternalFunction(char *library_name,
/*
* Establish the dynamic shared memory segment for a parallel context and
- * copied state and other bookkeeping information that will need by parallel
- * workers into it.
+ * copy state and other bookkeeping information that will be needed by
+ * parallel workers into it.
*/
void
InitializeParallelDSM(ParallelContext *pcxt)
@@ -271,7 +271,7 @@ InitializeParallelDSM(ParallelContext *pcxt)
* parallelism than to fail outright.
*/
segsize = shm_toc_estimate(&pcxt->estimator);
- if (pcxt->nworkers != 0)
+ if (pcxt->nworkers > 0)
pcxt->seg = dsm_create(segsize, DSM_CREATE_NULL_IF_MAXSEGMENTS);
if (pcxt->seg != NULL)
pcxt->toc = shm_toc_create(PARALLEL_MAGIC,
@@ -397,11 +397,13 @@ ReinitializeParallelDSM(ParallelContext *pcxt)
char *error_queue_space;
int i;
- if (pcxt->nworkers_launched == 0)
- return;
-
- WaitForParallelWorkersToFinish(pcxt);
- WaitForParallelWorkersToExit(pcxt);
+ /* Wait for any old workers to exit. */
+ if (pcxt->nworkers_launched > 0)
+ {
+ WaitForParallelWorkersToFinish(pcxt);
+ WaitForParallelWorkersToExit(pcxt);
+ pcxt->nworkers_launched = 0;
+ }
/* Reset a few bits of fixed parallel state to a clean state. */
fps = shm_toc_lookup(pcxt->toc, PARALLEL_KEY_FIXED);
@@ -420,9 +422,6 @@ ReinitializeParallelDSM(ParallelContext *pcxt)
shm_mq_set_receiver(mq, MyProc);
pcxt->worker[i].error_mqh = shm_mq_attach(mq, pcxt->seg, NULL);
}
-
- /* Reset number of workers launched. */
- pcxt->nworkers_launched = 0;
}
/*
@@ -493,6 +492,7 @@ LaunchParallelWorkers(ParallelContext *pcxt)
*/
any_registrations_failed = true;
pcxt->worker[i].bgwhandle = NULL;
+ pfree(pcxt->worker[i].error_mqh);
pcxt->worker[i].error_mqh = NULL;
}
}
--
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