openstack/oslo.messaging
Code Issues Proposed changes

Fix queue_manager in a containerized environment

Browse Source 
This patch fixes the operation of queue_manager in a
containerized environment by adding an additional check
on the start_time in ticks since boot.
This way, we can detect a restart even when the PID remains
unchanged as it is ussual in containers, but the start_time is
different.

[1] https://www.man7.org/linux/man-pages//man5/proc_pid_stat.5.html

From man page above:

(22) starttime  %llu
    The time the process started after system boot.
    Before Linux 2.6, this value was expressed in
    jiffies.  Since Linux 2.6, the value is expressed
    in clock ticks (divide by sysconf(_SC_CLK_TCK)).

Closes-Bug: #2078935
Change-Id: I9e22433ec039ad6783593d9cb7fbe22c9090534e
This commit is contained in:
Michal Arbet 2024-09-04 19:01:56 +02:00 committed by Takashi Kajinami
parent d601f7aae0
commit 6790f702fa
1 changed files with 22 additions and 11 deletions
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33
oslo_messaging/_drivers/amqpdriver.py
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@ -66,6 +66,13 @@ class QManager(object):
# We use the process group to restart the counter on service restart
self.pg = os.getpgrp()
# We need to also handle containerized deployments, so let's
# parse start time (in jiffies) since system boot
#
# https://www.man7.org/linux/man-pages//man5/proc_pid_stat.5.html
with open(f'/proc/{self.pg}/stat', 'r') as f:
self.start_time = int(f.read().split()[21])
def get(self):
lock_name = 'oslo_read_shm_%s_%s' % (self.hostname, self.processname)
@ -75,28 +82,32 @@ class QManager(object):
# This function is thread and process safe thanks to lockutils
try:
with open(self.file_name, 'r') as f:
pg, c = f.readline().split(':')
pg, counter, start_time = f.readline().split(':')
pg = int(pg)
c = int(c)
counter = int(counter)
start_time = int(start_time)
except (FileNotFoundError, ValueError):
pg = self.pg
c = 0
counter = 0
start_time = self.start_time
# Increment the counter
if pg == self.pg:
c += 1
if pg == self.pg and start_time == self.start_time:
counter += 1
else:
# The process group changed, maybe service restarted?
# The process group is changed, or start time since system boot
# differs. Maybe service restarted ?
# Start over the counter
c = 1
counter = 1
# Write the new counter
with open(self.file_name, 'w') as f:
f.write(str(self.pg) + ':' + str(c))
return c
f.write(str(self.pg) + ':' + str(counter) + ':' +
str(start_time))
return counter
c = read_from_shm()
return self.hostname + ":" + self.processname + ":" + str(c)
counter = read_from_shm()
return self.hostname + ":" + self.processname + ":" + str(counter)
class MessageOperationsHandler(object):