GC logging

By default, Elasticsearch enables GC logs. These are configured in jvm.options and output to the same default location as the Elasticsearch logs. The default configuration rotates the logs every 64 MB and can consume up to 2 GB of disk space.

You can reconfigure JVM logging using the command line options described in JEP 158: Unified JVM Logging. Unless you change the default jvm.options file directly, the Elasticsearch default configuration is applied in addition to your own settings. To disable the default configuration, first disable logging by supplying the -Xlog:disable option, then supply your own command line options. This disables all JVM logging, so be sure to review the available options and enable everything that you require.

To see further options not contained in the original JEP, see Enable Logging with the JVM Unified Logging Framework.

Examples

• Change the default GC log output location to /opt/my-app/gc.log by creating $ES_HOME/config/jvm.options.d/gc.options with some sample options:

  # Turn off all previous logging configuratons
  -Xlog:disable
  # Default settings from JEP 158, but with `utctime` instead of `uptime` to match the next line
  -Xlog:all=warning:stderr:utctime,level,tags
  # Enable GC logging to a custom location with a variety of options
  -Xlog:gc*,gc+age=trace,safepoint:file=/opt/my-app/gc.log:utctime,pid,tags:filecount=32,filesize=64m

• Configure an Elasticsearch Docker container to send GC debug logs to standard error (stderr). This lets the container orchestrator handle the output. If using the ES_JAVA_OPTS environment variable, specify:

  MY_OPTS="-Xlog:disable -Xlog:all=warning:stderr:utctime,level,tags -Xlog:gc=debug:stderr:utctime"
  docker run -e ES_JAVA_OPTS="$MY_OPTS" # etc