PM2 Does not capture Python stdout

[NotSoSuper]

What's going wrong?

When using PM2 to run a Python application none of the stdout from print or etc is captured to the log files.

How could we reproduce this issue?

Run a Python script such as print('test') with pm2 start test.py --interpreter python3.6
then pm2 logs

Supporting information

Please run the following command (available on PM2 >= 2.6)

$ pm2 report
===============================================================================
--- PM2 REPORT (Tue Aug 08 2017 12:55:16 GMT-0400 (EDT)) ----------------------
===============================================================================
--- Daemon -------------------------------------------------
pm2d version         : 2.6.1
node version         : 7.10.1
node path            : /usr/bin/pm2
argv                 : /usr/bin/nodejs,/usr/lib/node_modules/pm2/lib/Daemon.js
argv0                : node
user                 : notsobot
uid                  : 1001
gid                  : 1012
uptime               : 147min
===============================================================================
--- CLI ----------------------------------------------------
local pm2            : 2.6.1
node version         : 7.10.1
node path            : /usr/bin/pm2
argv                 : /usr/bin/nodejs,/usr/bin/pm2,report
argv0                : node
user                 : notsobot
uid                  : 1001
gid                  : 1012
===============================================================================
--- System info --------------------------------------------
arch                 : x64
platform             : linux
type                 : Linux
cpus                 : Intel(R) Xeon(R) CPU E5-1650 v2 @ 3.50GHz
cpus nb              : 12
freemem              : 895717376
totalmem             : 33701502976
home                 : /home/notsobot
===============================================================================
--- PM2 list -----------------------------------------------
┌────────────────────┬────┬──────┬───────┬────────┬─────────┬────────┬─────┬────────────┬──────────┬──────────┐
│ App name           │ id │ mode │ pid   │ status │ restart │ uptime │ cpu │ mem        │ user     │ watching │
├────────────────────┼────┼──────┼───────┼────────┼─────────┼────────┼─────┼────────────┼──────────┼──────────┤
│ bot00              │ 1  │ fork │ 9739  │ online │ 0       │ 21m    │ 6%  │ 623.8 MB   │ notsobot │ disabled │
│ pm2-http-interface │ 0  │ fork │ 25512 │ online │ 0       │ 87m    │ 0%  │ 38.3 MB    │ notsobot │ disabled │
└────────────────────┴────┴──────┴───────┴────────┴─────────┴────────┴─────┴────────────┴──────────┴──────────┘
===============================================================================
--- Daemon logs --------------------------------------------
/home/notsobot/.pm2/pm2.log last 20 lines:
PM2        | 2017-08-08 10:27:26: PM2 PID file         : /home/notsobot/.pm2/pm2.pid
PM2        | 2017-08-08 10:27:26: RPC socket file      : /home/notsobot/.pm2/rpc.sock
PM2        | 2017-08-08 10:27:26: BUS socket file      : /home/notsobot/.pm2/pub.sock
PM2        | 2017-08-08 10:27:26: Application log path : /home/notsobot/.pm2/logs
PM2        | 2017-08-08 10:27:26: Process dump file    : /home/notsobot/.pm2/dump.pm2
PM2        | 2017-08-08 10:27:26: Concurrent actions   : 2
PM2        | 2017-08-08 10:27:26: SIGTERM timeout      : 1600
PM2        | 2017-08-08 10:27:26: ===============================================================================
PM2        | 2017-08-08 11:18:59: Starting execution sequence in -fork mode- for app name:pm2-http-interface id:0
PM2        | 2017-08-08 11:18:59: App name:pm2-http-interface id:0 online
PM2        | 2017-08-08 11:27:33: 0
PM2        | 2017-08-08 11:27:33: Stopping app:pm2-http-interface id:0
PM2        | 2017-08-08 11:27:33: App [pm2-http-interface] with id [0] and pid [23425], exited with code [0] via signal [SIGINT]
PM2        | 2017-08-08 11:27:33: pid=23425 msg=process killed
PM2        | 2017-08-08 11:27:38: Starting execution sequence in -fork mode- for app name:pm2-http-interface id:0
PM2        | 2017-08-08 11:27:38: App name:pm2-http-interface id:0 online
PM2        | 2017-08-08 11:28:22: 25512 : id unknown
PM2        | 2017-08-08 11:28:33: 25512 : id unknown
PM2        | 2017-08-08 12:33:42: Starting execution sequence in -fork mode- for app name:bot00 id:1
PM2        | 2017-08-08 12:33:42: App name:bot00 id:1 online

[vmarchaud]

Can't produce :

[martinsteinorth]

Having the same problem with long running python scripts. I get the output if the script terminates on its own, but there is no output if it is a long running script.

Try

import time
while True:
    print("PING")
    time.sleep(1)

PM2 2.9.3
Node 8.9.4
Linux on arm arch

[Unitech]

PYTHONUNBUFFERED=x

[Unitech]

fixed, it will land on next release

[Unitech]

It has been fixed and landed on the latest pm2 version, check it out:

npm install pm2 -g
pm2 update

Also checkout this article about the support of PM2 for Python: https://blog.pm2.io/managing-python-application-with-pm2/