Summary

Rename hsperfdata counter sun.gc.policy.gcTimeLimitExceeded to sun.gc.policy.gcOverheadLimitExceeded and change its runtime behavior from a boolean value to a cumulative counter.

Problem

The name gcTimeLimitExceeded is a misnomer, as its implementation takes into account both GC time limit and space limit. The counter currently holds a boolean value that is updated at every garbage collection, making it difficult for monitoring tools to catch the moment when it is set to true, as the next collection could reset it to false before the monitoring tools read the counter.

Solution

Rename the counter to sun.gc.policy.gcOverheadLimitExceeded, and change its runtime behavior to a cumulative integer, which denotes the total number of collections that have triggered the "GC overhead limit exceeded" event. In this way monitoring tools can periodically poll the counter, without worrying about missing any update to the counter. When a Java process OOMs and terminates due to "GC overhead limit exceeded", the counter is guaranteed to hold a non-zero value.

Specification

sun.gc.policy.gcTimeLimitExceeded will be removed. sun.gc.policy.gcOverheadLimitExceeded will be added, denoting the total number of collections that have triggered the "GC overhead limit exceeded" event.