We see this kind of messages in the logs of Travis builds each time a JVM is spawned:

Picked up _JAVA_OPTIONS: -Xmx2048m -Xms512m

This comes from Travis setting up the _JAVA_OPTIONS environment variable in container environments.

The goal is to limit the amount of memory used by JVMs in containers, which is fine. Unfortunately, the _JAVA_OPTIONS environment variable takes precedence over arguments passed in the command line, such as Elasticsearch servers we spawn during the Maven build, and this ends up raising the amount of memory used by some JVMs, and sometimes makes the build fail.

See also https://github.com/travis-ci/travis-ci/issues/8408

We should unset this environment variable in our .travis.yml, and either move its value to JAVA_TOOLS_OPTIONS, which does not take precedence over command line arguments, or simply ignore it.

See also https://stackoverflow.com/questions/28327620/difference-between-java-options-java-tool-options-and-java-opts