Question

I have a question for java GC. I know that there is minor collection for young generation and major collection for tenured generation and normally the size of YG is smaller than the size of tenured generation. So the minor collection occurs more often than the major collection.

My question is that when the minor collection and major collection start, how do they impact the application threads differently?

If the minor collection occurs more often, does it make the application threads pause more often even though it collects garbage objects quickly?

Thanks.

Answer 1

My question is that when the minor collection and major collection start, how do they impact the application threads differently? If the minor collection occurs more often, does it make the application threads pause more often even though it collects garbage objects quickly?

The simple answer is that your question is (almost) a tautology. If a minor collection occurs more often, and a minor collection causes an application pause, then of course this makes the application pause more often.

The real answer is that the behaviour depends on the sizes of the respective spaces (e.g. YG versus YG + TG) and … more importantly … on the GC that you’ve configured your JVM to use. For instance if you are using a low-pause collector then the pauses shouldn’t be noticeable … unless you push the limits too far.

Note that it is the length of pauses, not the frequency of pauses that matters. Pauses that are too short to notice don’t hurt anyone.