On Fri, Mar 7, 2014 at 2:40 PM, Robert Haas <robertmh...@gmail.com> wrote:
>> The big picture here is that in the scenario being debated in the other
>> thread, exit() in a child process forked from a backend will execute that
>> backend's on_detach actions *even if the code had done on_exit_reset after
>> the fork*.
>
> Hmm. So the problematic sequence of events is where a postmaster
> child forks, and then exits without exec-ing, perhaps because e.g.
> exec fails?
I've attempted a fix for this case. The attached patch makes
test_shm_mq fork() a child process that calls on_exit_reset() and then
exits. Without the fix I just pushed, this causes the tests to fail;
with this fix, this does not cause the tests to fail.
I'm not entirely sure that this is exactly right, but I think it's an
improvement.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
diff --git a/contrib/test_shm_mq/test.c b/contrib/test_shm_mq/test.c
index 59f18ec..f6b9dd4 100644
--- a/contrib/test_shm_mq/test.c
+++ b/contrib/test_shm_mq/test.c
@@ -13,8 +13,11 @@
#include "postgres.h"
+#include <unistd.h>
+
#include "fmgr.h"
#include "miscadmin.h"
+#include "storage/ipc.h"
#include "test_shm_mq.h"
@@ -72,6 +75,15 @@ test_shm_mq(PG_FUNCTION_ARGS)
/* Set up dynamic shared memory segment and background workers. */
test_shm_mq_setup(queue_size, nworkers, &seg, &outqh, &inqh);
+ /* Try forking a child that immediately exits. */
+ if (fork() == 0)
+ {
+ elog(LOG, "child is PID %d", getpid());
+ on_exit_reset();
+ exit(0);
+ }
+ elog(LOG, "parent is PID %d", getpid());
+
/* Send the initial message. */
res = shm_mq_send(outqh, message_size, message_contents, false);
if (res != SHM_MQ_SUCCESS)
--
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