Hi,
I've been trying to run some pg_ctl command inside a python script,
and saw that some of them where deadlocking. It seems that the
commands that start postgres handle stdout in a way that that block
the caller. Redirecting stdout to /dev/null or to a file using the -l
option allow me to workaround the problem, but fixing it upstream
would be nice.
Here's a simple python program that reproduces the problem, and should deadlock.
Customize your data path first, of course.
Regards,
--
Luis MENINA / Software Engineer
Web: www.anevia.com
Anevia: 1 rue René Anjolvy, 94250 Gentilly, France
#! /usr/bin/env python
import subprocess
PGDATADIR = '/mnt/streams1/pgsql/localdb/data'
# WORKS !!! (because of stdout redirection)
#cmd = 'sudo -u postgres /usr/lib/postgresql/9.3/bin/pg_ctl restart -w -s -m fast -D ' + PGDATADIR + ' /dev/null'
#cmd = 'sudo -u postgres /usr/lib/postgresql/9.3/bin/pg_ctl restart -w -s -m fast -D ' + PGDATADIR + ' -l /tmp/postgres.log'
# BROKEN !!!
#cmd = 'sudo -u postgres /usr/lib/postgresql/9.3/bin/pg_ctl restart -w -s -m fast -D ' + PGDATADIR + ' 21'
cmd = 'sudo -u postgres /usr/lib/postgresql/9.3/bin/pg_ctl restart -w -s -m fast -D ' + PGDATADIR
print cmd
print Running subprocess.check_output
subprocess.check_output(cmd, shell=True)
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