[Q&A]

[Athishpranav2003]

What is a problem?

infinite recursion when router.emit is called inside filter plugin

Describe the configuration of Fluentd

No response

Describe the logs of Fluentd

#<Thread:0x000000012802e058@event_loop /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/plugin_helper/thread.rb:70 run> terminated with exception (report_on_exception is true):
/usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:292:in `new': stack level too deep (SystemStackError)
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:292:in `block in find'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:289:in `each'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:289:in `each_with_index'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:289:in `find'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:135:in `block in match'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:153:in `get'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:134:in `match'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:115:in `emit_stream'
	 ... 5757 levels...
	from /usr/local/lib/ruby/gems/3.3.0/gems/cool.io-1.8.1/lib/cool.io/loop.rb:88:in `run_once'
	from /usr/local/lib/ruby/gems/3.3.0/gems/cool.io-1.8.1/lib/cool.io/loop.rb:88:in `run'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/plugin_helper/event_loop.rb:93:in `block in start'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/plugin_helper/thread.rb:78:in `block in thread_create'
/usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:292:in `new': stack level too deep (SystemStackError)
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:292:in `block in find'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:289:in `each'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:289:in `each_with_index'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:289:in `find'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:135:in `block in match'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:153:in `get'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:134:in `match'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/event_router.rb:115:in `emit_stream'
	 ... 5757 levels...
	from /usr/local/lib/ruby/gems/3.3.0/gems/cool.io-1.8.1/lib/cool.io/loop.rb:88:in `run_once'
	from /usr/local/lib/ruby/gems/3.3.0/gems/cool.io-1.8.1/lib/cool.io/loop.rb:88:in `run'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/plugin_helper/event_loop.rb:93:in `block in start'
	from /usr/local/lib/ruby/gems/3.3.0/gems/fluentd-1.17.0/lib/fluent/plugin_helper/thread.rb:78:in `block in thread_create'

Environment

- Fluentd version: 1.17.0

[daipom]

Thanks for the report.
Could you share your config?
I want to know how to reproduce this.

[Athishpranav2003]

This is something i am working as a part of plugin development.

def filter(tag, time, record)
 router.emit("dummy",time,record)
 return nil
end

This is the filter method i am using
i guess with this you can reproduce the issue by replacing the function https://docs.fluentd.org/plugin-development/api-plugin-filter

[Athishpranav2003]

It got fixed now @daipom
I guess my filter was trying to consume the same thing it emitted
thats why this error occured
now it works

[daipom]

I'm glad it's resolved!