Reasons for frequent Full GC

Trigger Full GC. Please refer to https://blog.51cto.com/11009785/2399498

Reasons for frequent Full GC:

1. The space of the older generation is relatively small.

Solution: first, increase the space of the older generation. Second: use CMS GC to recycle the older generation to reduce the probability of full gc.

two。 System.gc () was called

Solution:-XX:+DisableExplicitGC ignores the manual call to GC, and the call to System.gc () becomes an air conditioner without triggering GC at all.

Note:

How do you locate the code that calls System.gc ()?

If the frequent Full GC,jstack thread stack is caused by System.gc (), you should see some information.

Jstack: view thread stack information within a Java process

Jstack can navigate to the thread stack, and we can navigate to specific code based on stack information, so it is used a lot in JVM performance tuning.

Note 1: in the information displayed, focus on the code written by yourself, and take screenshots for the developer.

Note 2: it is possible that jstack cannot capture the required information at one time, so it needs to be executed multiple times, because it captures the state of that moment.