Manage JVM memory
You can manage Java Virtual Machine (JVM) memory usage for Besu by modifying the maximum heap size.
By default, the JVM uses 25% of system RAM. For example, if you have 16 GB RAM installed, the JVM uses 4 GB by default.
On public networks, we recommend setting the maximum heap size to:
- 3 GB on an 8 GB RAM system.
- 5 GB on a 16 GB RAM system.
- 8 GB on a system with at least 24 GB RAM.
Setting a higher maximum heap size speeds up the sync period but doesn't have much impact after sync. Thus, we recommend setting it to 8 GB only when you have available RAM.
You can set the maximum heap size using the
BESU_OPTS environment variable and the
-Xmx option. The following examples set the maximum heap size to 8 GB:
- Exported environment variable example
- Inline environment variable example
- .service file example
Set the variable for the whole shell before running Besu.
Set the variable only for the specific Besu command.
BESU_OPTS=-Xmx8g besu [Besu options]
ExecStart=besu [Besu options]
Manage the heap dump
Heap dump file generation is disabled by default. To enable it, set the
-XX:+HeapDumpOnOutOfMemoryError Java option.
When heap dump file generation is enabled, and an out-of-memory error occurs, the heap dump file is saved in the Besu runtime directory by default.
The heap dump file might be large and can saturate your drive. It can be up to the size of the allocated memory. For example, for 8 GB heap memory, the file can be up to 8 GB. Specify the directory where you want the dump to be saved using the
-XX:HeapDumpPath Java option.