If you read that log, you can spot an out of memory exception. This means you have to restart your node immediately, as the behaviour after such an exception is not specified (you just dont know if everything works or not).
However in order to prevent those issues in the future, you should find out what triggers this exception. Is it a special query?
You might want to read the following docs regarding to that topic
You can use the cat APIs or monitoring to see if you have continously rising memory usages or spikes which cause this behaviour.
Hope this helps.
--Alex