Each standalone JobManager, TaskManager, HistoryServer, and ZooKeeper daemon redirects
stderr to a file
.out filename suffix and writes internal logging to a file with a
.log suffix. Java options configured by the
env.java.opts.historyserver can likewise define log files with
use of the script variable
FLINK_LOG_PREFIX and by enclosing the options in double quotes for late evaluation. Log files
FLINK_LOG_PREFIX are rotated along with the default
Java Flight Recorder is a profiling and event collection framework built into the Oracle JDK. Java Mission Control is an advanced set of tools that enables efficient and detailed analysis of the extensive of data collected by Java Flight Recorder. Example configuration:
JITWatch is a log analyser and visualizer for the Java HotSpot JIT compiler used to inspect inlining decisions, hot methods, bytecode, and assembly. Example configuration:
If you encounter
OutOfMemoryExceptions with your Flink application, then it is a good idea to enable heap dumps on out of memory errors.
The heap dump will allow you to analyze potential memory leaks in your user code. If the memory leak should be caused by Flink, then please reach out to the dev mailing list.
Memory usage and garbage collection can have a profound impact on your application.
The effects can range from slight performance degradation to a complete cluster failure if the GC pauses are too long.
If you want to better understand the memory and GC behaviour of your application, then you can enable memory logging on the
If you are interested in more detailed GC statistics, then you can activate the JVM’s GC logging via: