After Logstash upgrade from 5.6.2 to 6.2.4 log4j input plugin started to introduce large log delivery delay.
Seems like this's happening because Logstash is waiting for some specified amount of input data from log4j client (in some cases it can take up to 10 minutes).
In version 5.6.14 all works as expected and Logstash sends from input to filter chain every new event from log4j but such behavior definitely changed in Logstash 6.0.0.
I know that log4j plugin deprecated but is there any way to change/revert this behavior? or at least does somebody know what can introduce introduce this problem?