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 + ' 2>&1' 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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