Fix a potential bug that ThreadError may occur on SIGUSR1

[ashie]

Which issue(s) this PR fixes:

None in GitHub issues, but it will fix the following bug report:

• https://groups.google.com/d/msg/fluentd/Ten_apYLAX8/PD4jYk8KDwAJ

We ClearCode Inc. recently received same bug reports from our some customers.
Their fluentd is v0.12 but I think the same potential bug still exists in the latest version.

What this PR does / why we need it:

This PR removes redundant run calls for some Thread objects.
It may cause the following error on SIGUSR1:

[error]: unexpected error error_class=ThreadError error=#<ThreadError: killed thread>

as reported in

• https://groups.google.com/d/msg/fluentd/Ten_apYLAX8/PD4jYk8KDwAJ

because the new thread may finish before calling "run" method at main
thread.

In addition this PR also replaces { ... } style blocks for them with do ... end style,
because the later style will clarify such mistakes.

Docs Changes:

None.

Release Note:

Same as title

[repeatedly]

Looks good. Thanks!

[savy1212]

Which fluentd version this fix is given??

I am facing the same issue in fluent-plugins-3.4.1-1.0.2.x86_64

[daipom]

v1.8

https://github.com/fluent/fluentd/blob/master/CHANGELOG.md#v18

[savy1212]

Thanks, I am not good at fluentd.

So that means my fluentd version is 1.2.2 and older than the fixed version right!!

2023-03-08 17:45:01 +0800 [error]: #0 unexpected error error_class=ThreadError error="killed thread"
2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/supervisor.rb:704:in run' 2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/supervisor.rb:704:in flush_buffer'
2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/supervisor.rb:664:in block in install_main_process_signal_handlers' 2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/engine.rb:228:in sleep'
2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/engine.rb:228:in run' 2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/supervisor.rb:799:in run_engine'
2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/supervisor.rb:549:in block in run_worker' 2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/supervisor.rb:724:in main_process'
2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/supervisor.rb:544:in run_worker' 2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/lib/fluent/command/fluentd.rb:316:in <top (required)>'
2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in require' 2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in require'
2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/lib/ruby/gems/2.4.0/gems/fluentd-1.2.2/bin/fluentd:8:in <top (required)>' 2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/bin/fluentd:23:in load'
2023-03-08 17:45:01 +0800 [error]: #0 /opt/td-agent/embedded/bin/fluentd:23:in `

'
2023-03-08 17:45:01 +0800 [error]: #0 unexpected error error_class=ThreadError error="killed thread"
2023-03-08 17:45:01 +0800 [error]: #0 suppressed same stacktrace

[daipom]

Yes!
There are some Fluentd packages such as td-agent.
The version of the package and the version of Fluentd embedded in it may differ.

[savy1212]

Thanks again, my td-agent package is td-agent-3.2.0-0.el7.x86_64.
It actually led to a major impact; I think I should go ahead with the upgrade.

[daipom]

If you are updating to the latest version of td-agent v4, the following blog may be helpful.

https://www.fluentd.org/blog/upgrade-td-agent-v3-to-v4

[savy1212]

We have had this log rotation happening 4 times a day for like 1 year and working fine, now suddenly this bug is triggered, we are not sure what can trigger this bug,

Are there specific scenarios that can trigger this bug?

Also is there a way to just edit the supervisor.rb of fluent 1.2.2 file with the fix mentioned in this bug by removing extra run from the code if we dont want to upgrade, will it work?