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 20 events.
% bin/logstash -e 'input { generator { } } filter { ruby { code => "sleep 10000" } } \
output { stdout { codec => dots } }' -w 1 --allow-unsafe-shutdown
Default settings used: Filter workers: 1
Logstash startup completed
^CSIGINT received. Shutting down the pipeline. {:level=>:warn}
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}
{:level=>:warn, "INFLIGHT_EVENT_COUNT"=>{"input_to_filter"=>20, "total"=>20},
"STALLING_THREADS"=>
{["LogStash::Filters::Ruby", {"code"=>"sleep 10000"}]=>[{"thread_id"=>15,
"name"=>"|filterworker.0", "current_call"=>"
(ruby filter code):1:in `sleep'"}]}}
The shutdown process appears to be stalled due to busy or blocked plugins. Check
the logs for more information.
{:level=>:error}
{:level=>:warn, "INFLIGHT_EVENT_COUNT"=>{"input_to_filter"=>20, "total"=>20},
"STALLING_THREADS"=>
{["LogStash::Filters::Ruby", {"code"=>"sleep 10000"}]=>[{"thread_id"=>15,
"name"=>"|filterworker.0", "current_call"=>"
(ruby filter code):1:in `sleep'"}]}}
{:level=>:warn, "INFLIGHT_EVENT_COUNT"=>{"input_to_filter"=>20, "total"=>20},
"STALLING_THREADS"=>
{["LogStash::Filters::Ruby", {"code"=>"sleep 10000"}]=>[{"thread_id"=>15,
"name"=>"|filterworker.0", "current_call"=>"
(ruby filter code):1:in `sleep'"}]}}
Forcefully quitting logstash.. {:level=>:fatal}
When --allow-unsafe-shutdown isn’t enabled, Logstash continues to run and produce these reports periodically.