Geek asks and answers

Can the OS stop the Java process from garbage collection?

I track the production system with AppDynamics , and we just started the system with a crawl and almost froze. Just before this event, AppDynamics shows all the activities of the GC (small and large similar) for several minutes ... and then comes back to life.

Even during periods of ultra-low system load, we still see that our JVMs perform some GC activity. We never had a completely flat line and it fell to 0.

In addition, network I / O is focused at the same instance of time as the solid GC / memory line.

So I ask: can something at the system level cause the JVM to freeze or cause garbage collection / freezing? This is on a CentOS machine.

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3 answers

Is your swap OS enabled?

I noticed HUGE problems with Java when it fills all the bars on the OS with the replacement enabled - this actually decrypts Windows systems, effectively blocking them and causing a reboot.

My theory is this:

  • OS operating system is completely closed.
  • The OS retrieves memory from Java back.
  • This runs Java in a full GC to try to free memory.
  • A full GC applies to almost every piece of virtual machine memory, even items that have been replaced.
  • The system is trying to exchange data back to memory for the virtual machine (on a system that is already offline)
  • This leads to snowy snow.

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