Stalled Shutdown Detection
editStalled Shutdown Detection
editShutting down a running Logstash instance involves the following steps:
- Stop all input, filter and output plugins
- Process all in-flight events
- Terminate the Logstash process
The following conditions affect the shutdown process:
- An input plugin receiving data at a slow pace.
-
A slow filter, like a Ruby filter executing
sleep(10000)or an Elasticsearch filter that is executing a very heavy query. - A disconnected output plugin that is waiting to reconnect to flush in-flight events.
These situations make the duration and success of the shutdown process unpredictable.
Logstash has a stall detection mechanism that analyzes the behavior of the pipeline and plugins during shutdown. This mechanism produces periodic information about the count of inflight events in internal queues and a list of busy worker threads.
To enable Logstash to forcibly terminate in the case of a stalled shutdown, use the --allow-unsafe-shutdown flag when
you start Logstash.
Stall Detection Example
editIn this example, slow filter execution prevents the pipeline from clean shutdown. By starting Logstash with the
--allow-unsafe-shutdown flag, quitting with Ctrl+C results in an eventual shutdown that loses events.
bin/logstash -e 'input { generator { } } filter { ruby { code => "sleep 10000" } }
output { stdout { codec => dots } }' -w 1 --allow-unsafe-shutdown
Settings: User set pipeline workers: 1, Default pipeline workers: 8
Pipeline main started
^CSIGINT received. Shutting down the agent. {:level=>:warn}
stopping pipeline {:id=>"main"}
Received shutdown signal, but pipeline is still waiting for in-flight events
to be processed. Sending another ^C will force quit Logstash, but this may cause
data loss. {:level=>:warn}
{"inflight_count"=>125, "stalling_thread_info"=>{["LogStash::Filters::Ruby",
{"code"=>"sleep 10000"}]=>[{"thread_id"=>17, "name"=>"[main]>worker0",
"current_call"=>"(ruby filter code):1:in `sleep'"}]}} {:level=>:warn}
The shutdown process appears to be stalled due to busy or blocked plugins.
Check the logs for more information. {:level=>:error}
{"inflight_count"=>125, "stalling_thread_info"=>{["LogStash::Filters::Ruby",
{"code"=>"sleep 10000"}]=>[{"thread_id"=>17, "name"=>"[main]>worker0",
"current_call"=>"(ruby filter code):1:in `sleep'"}]}} {:level=>:warn}
{"inflight_count"=>125, "stalling_thread_info"=>{["LogStash::Filters::Ruby",
{"code"=>"sleep 10000"}]=>[{"thread_id"=>17, "name"=>"[main]>worker0",
"current_call"=>"(ruby filter code):1:in `sleep'"}]}} {:level=>:warn}
Forcefully quitting logstash.. {:level=>:fatal}
When --allow-unsafe-shutdown isn’t enabled, Logstash continues to run and produce these reports periodically.