How to add a delay to supervised process in supervisor – linux

Question:

I added a bottle server that uses python’s cassandra library, but it exits with this error:
Bottle FATAL Exited too quickly (process log may have details)
log shows this:
File "/usr/local/lib/python2.7/dist-packages/cassandra/cluster.py", line 1765, in _reconnect_internal
raise NoHostAvailable("Unable to connect to any servers", errors)

So I tried to run it manually using supervisorctl start Bottle ,and then it started with no issue. The conclusion= Bottle service starts too fast (before the needed cassandra supervised service does): a delay is needed!

Asked By: Zack S

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Answers:

This is what I use:

[program:uwsgi]
command=bash -c 'sleep 5 && uwsgi /etc/uwsgi.ini'
Answered By: DeeY

Not happy enough with the sleep hack I created a startup script and launched supervisorctl start processname from there.

[program:startup]
command=/startup.sh
startsecs = 0
autostart = true
autorestart = false
startretries = 1
priority=1

[program:myapp]
command=/home/website/venv/bin/gunicorn /home/website/myapp/app.py
autostart=false
autorestart=true
process_name=myapp

startup.sh

#!/bin/bash
sleep 5
supervisorctrl start myapp

This way supervisor will fire the startup script once and this will start myapp after 5 seconds, mind the autostart=false and autorestart=true on myapp.

Answered By: MGP

I had a similar issue where, starting 64 python rq-worker processes using supervisorctl was raising CPU and RAM alert at every restart. What I did was the following:

command=/bin/bash -c "sleep %(process_num)02d && virtualenv/bin/python3 manage.py rqworker --name %(program_name)s_my-rq-worker_%(process_num)02d default low"

Basically, before running the python command, I sleep for N second, where N is the process number, which basically means I supervisor will start one rq-worker process every second.

Answered By: Emmanuel Iturbide