fileCreateOperation of maven build log (with -X) makes heap memory consumption growth up to N*(log size) because of env vars expansion step here: 

https://github.com/jenkinsci/file-operations-plugin/blob/master/src/main/java/sp/sd/fileoperations/FileCreateOperation.java#L46

result = ws.act(new TargetFileCallable(listener, envVars.expand(fileName), envVars.expand(fileContent), envVars)); 

During this step on big fileContent (600MB) Heap memory grows, GC permanently tries to clean, web interface hangs, Jenkins Master goes down for dozen of minutes.

We've faced this issue few times on different instances

Workaround: find SynchronousNonBlockingStepExecution thread whith highest memory allocation rate with memory profiler (visualvm) and try to stop it by javamelody (${JENKINS_URL}/monitoring?part=threads), or completely restart service.

I think it would be great to limit fileContent size or optionally disable envVars.expand to preven