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supervisor could die on some signals #1723

abicky opened this Issue Oct 22, 2017 · 1 comment


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abicky commented Oct 22, 2017

I found supervisor died on signals if its worker had died unexpectedly before, for example, killed by OOM Killer, SEGV and so on.
It seems to be because config[:worker_pid] includes the pid of the dead worker.

Steps to reproduce

  1. Run fluentd
% docker run -it --rm --name fluentd fluent/fluentd:v0.14.21
  1. Kill the worker
% docker exec -it fluentd sh
/ # ps
    1 root       0:00 {} /usr/bin/dumb-init /bin/sh /bin/ /bin/sh -c exec fluentd -c /fluentd/etc/${FLUENTD_CONF} -p /fluentd/plugins $FLUENTD_OPT
    5 fluent     0:00 {fluentd} /usr/bin/ruby /usr/bin/fluentd -c /fluentd/etc/fluent.conf -p /fluentd/plugins
   15 fluent     0:00 /usr/bin/ruby -Eascii-8bit:ascii-8bit /usr/bin/fluentd -c /fluentd/etc/fluent.conf -p /fluentd/plugins --under-supervisor
   23 root       0:00 sh
   27 root       0:00 ps
/ # kill -KILL 15
  1. Send a signal to the supervisor
/ # kill -USR1 1
  1. The supervisor dies
Unexpected error No such process
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/lib/fluent/supervisor.rb:168:in `kill'
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/lib/fluent/supervisor.rb:168:in `block in supervisor_sigusr1_handler'
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/lib/fluent/supervisor.rb:167:in `each'
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/lib/fluent/supervisor.rb:167:in `supervisor_sigusr1_handler'
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/lib/fluent/supervisor.rb:137:in `block in install_supervisor_signal_handlers'
  /usr/lib/ruby/gems/2.3.0/gems/serverengine-2.0.5/lib/serverengine/process_manager.rb:252:in `select'
  /usr/lib/ruby/gems/2.3.0/gems/serverengine-2.0.5/lib/serverengine/process_manager.rb:252:in `tick'
  /usr/lib/ruby/gems/2.3.0/gems/serverengine-2.0.5/lib/serverengine/multi_spawn_server.rb:91:in `wait_tick'
  /usr/lib/ruby/gems/2.3.0/gems/serverengine-2.0.5/lib/serverengine/multi_worker_server.rb:60:in `run'
  /usr/lib/ruby/gems/2.3.0/gems/serverengine-2.0.5/lib/serverengine/multi_spawn_server.rb:57:in `run'
  /usr/lib/ruby/gems/2.3.0/gems/serverengine-2.0.5/lib/serverengine/server.rb:123:in `main'
  /usr/lib/ruby/gems/2.3.0/gems/serverengine-2.0.5/lib/serverengine/daemon.rb:119:in `main'
  /usr/lib/ruby/gems/2.3.0/gems/serverengine-2.0.5/lib/serverengine/daemon.rb:68:in `run'
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/lib/fluent/supervisor.rb:606:in `supervise'
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/lib/fluent/supervisor.rb:476:in `run_supervisor'
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/lib/fluent/command/fluentd.rb:310:in `<top (required)>'
  /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
  /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
  /usr/lib/ruby/gems/2.3.0/gems/fluentd-0.14.21/bin/fluentd:5:in `<top (required)>'
  /usr/bin/fluentd:22:in `load'
  /usr/bin/fluentd:22:in `<main>'

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repeatedly commented Oct 31, 2017

This problem happens with restart/reload signals so ignoring this error should fix the problem.
I will it soon.

@repeatedly repeatedly self-assigned this Oct 31, 2017

@repeatedly repeatedly closed this in f51b609 Nov 9, 2017

repeatedly added a commit that referenced this issue Nov 9, 2017

Merge pull request #1739 from fluent/fix-worker_pid-handling
Fix worker_pid handling by replacing old pid with new one. fix #1723
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