GCOverheadLimit support for G1

[Thomas Schatzl]

Hi Sonia,

On 10.01.25 15:15, Sonia Zaldana Calles wrote:
> Hi folks,
> 
> 
> Upon migration from ParallelGC to G1, we have a report that G1 is 
> showcasing a slow death when too much time is spent in garbage 
> collection, in contrast to ParallelGC, which would trigger an 
> “OutOfMemoryError: GC Overhead limit exceeded”.
> 
> 
> Note the single class reproducer below [0]. Running with java ... - 
> Xlog:gc -Xmx4G, we can observe long pauses (~3-4 seconds on my machine), 
> the VM attempts ~20 Full GC cycles where the last full GCs take a lot 
> longer than the pause time goal of 200ms. Ideally, we would like the JVM 
> to stop trying at some point early (similarly to ParallelGC) and we have 
> not found a way to accomplish that.
> 
> 
> We found this is likely because UseGCOverheadLimit is only supported 
> (and enabled by default) for the ParallelGC. We came across JDK-8212084 
> and we were wondering if there was a particular reason this didn’t move 
> forward? [1] Is there anything we can do to help?
> 
> 

   as most of the time, I do not think there is a particular reason this 
work has not been completed. Just as the comments in that CR indicate, 
that the original problem went away for them and interest has been lost.

Hth,
   Thomas