Dear Euler,
I applied your patch and confirmed it could fix the issue [1].
METHOD
=======
1. shortened the snapshot interval to 3ms, and
```
-#define LOG_SNAPSHOT_INTERVAL_MS 15000
+#define LOG_SNAPSHOT_INTERVAL_MS 3
```
2. ran test 040_pg_createsubscriber.pl many times.
Before patching, I could reproduce the failure when I ran less than 1hr.
After patching, I ran more than 1hr but I could not reproduce.
Since this is a timing issue which I could not surely reproduce, I wanted others
to test it as well.
[1]: https://www.postgresql.org/message-id/68de6498-0449-a113-dd03-e198dded0bac%40gmail.com
Best regards,
Hayato Kuroda
FUJITSU LIMITED
