[pgpool-hackers: 3865] Pgpool-II main forgets to unlink pid file while exiting abnormally

[Tatsuo Ishii]

Just for fun, I set num_init_children to very large number like 32000
and tried to start pgpool:

:
:
2021-01-13 17:07:45: child pid 11674: DEBUG:  initializing backend status
2021-01-13 17:07:45: child pid 11673: DEBUG:  initializing backend status
2021-01-13 17:07:45: main pid 894: FATAL:  failed to fork a child
2021-01-13 17:07:45: main pid 894: DETAIL:  system call fork() failed with reason: Resource temporarily unavailable
2021-01-13 17:07:45: child pid 11676: DEBUG:  initializing backend status
2021-01-13 17:07:45: child pid 11679: DEBUG:  initializing backend status
2021-01-13 17:07:45: child pid 11678: DEBUG:  initializing backend status
2021-01-13 17:07:45: child pid 11677: DEBUG:  initializing backend status
2021-01-13 17:07:45: main pid 894: LOG:  shutting down

As expected, pgpool won't start because it tried to fork huge number
of children. This itself is fine but pgpool forgot to unlink pid file
while exiting. We need to fix this.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp