I tried setting wal_retrieve_retry_interval to 1ms for all TAP tests
(similar to what was done in 2710ccd), and I noticed that the recovery
tests consistently took much longer. Upon further inspection, it looks
like the same (or a very similar) race condition described in e5d494d's
commit message [0]. With some added debug logs, I see that all of the
callers of MaybeStartWalReceiver() complete before SIGCHLD is processed, so
ServerLoop() waits for a minute before starting the WAL receiver.
A simple fix is to have DetermineSleepTime() take the WalReceiverRequested
flag into consideration. The attached 0002 patch shortens the sleep time
to 100ms if it looks like we are waiting on a SIGCHLD. I'm not certain
this is the best approach, but it seems to fix the tests.
On my machine, I see the following improvements in the tests (all units in
seconds):
HEAD patched (v9)
check-world -j8 165 138
subscription 120 75
recovery 111 108
[0] https://postgr.es/m/21344.1498494720%40sss.pgh.pa.us
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Nathan Bossart
Amazon Web Services: https://aws.amazon.com
