Reducing memory usage

Default MaxRAM Setting

One of the settings java virtual machines (JVMs) use to calibrate how much physical memory to reserve at startup is MaxRAM, and there is a good chance your JVM's default MaxRAM configuration is too large.    To check the default MaxRAM setting, run this java version command:

   java -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version | grep MaxRAM

Look for the MaxRAM value (bytes) in the output; this machine says

   367: uint64_t MaxRAM = 137438953472 

This means the OpenJDK 11 JVM's MaxRAM setting is 128 GB, on a machine with only 16 GB RAM.

Experiments have shown running Bisq with a 4g (GB) MaxRAM setting reduces resident memory consumption by more than 50% (when starting a clean Bisq installation with an empty data directory).    Setting MaxRAM to 2g reduces resident memory usage even more, but setting it any lower (1536m) will result in an OutOfMemoryError and crash the app.

As of version 1.3.2, Bisq is started with a MaxRAM setting of 4g (GB).    If you are using Bisq v1.3.1 or older, consider upgrading to the latest version to benefit from this change.