Fix issue relate with CollectionUsageThreshold of memory pool

[LinHu2016]

- we should only check if the notification for
CollectionUsageThreshold need to be fired at the end of
the collection, which try to recycle the memory pool.
- for BackCompatible mode scavenge does not try to reclaim
memory from the whole heap, so we do not fire the notification of
CollectionUsageThreshold at the end scavenge.
- record the last GC ID for retrieving more detail gcInfo of
last GC from J9GarbageCollectorDataMemoryPoolMXBean
.getCollectionUsage() getPreCollectionUsage() and
isCollectionUsageThresholdExceeded() also match the same rule.
   - fix potential IllegalArgumentException issue.

relate:#2993

[pshipton]

jenkins test sanity plinux jdk8

[pshipton]

jenkins test extended plinux jdk8

[pshipton]

jenkins compile win jdk8

[DanHeidinga]

I'm having some trouble understanding this change as there's 1 gcInfo and potentially many memoryPools and this change seems to be collecting the data in the gcInfo and then applying it to the memoryPools.

I don't understand why its being changed this way rather than keeping the data in the memory pools and agregating it in the gcInfo.

Once I understand that, I'll be in a better position to review this.

[LinHu2016]

I'm having some trouble understanding this change as there's 1 gcInfo and potentially many memoryPools and this change seems to be collecting the data in the gcInfo and then applying it to the memoryPools.

I don't understand why its being changed this way rather than keeping the data in the memory pools and agregating it in the gcInfo.

Once I understand that, I'll be in a better position to review this.

Hi @DanHeidinga, according to JAVA Spec, preCollection(IBM Java only), postCollection Memory Usage in memoryPool only keep information for the GC, which recycle the memory pool. For the case gencon, Tenure memorypool would only update after global gc, scavenge does not reclaim tenure memorypool( actually it consumes tenure space).

for the details, please check java doc for MemoryPoolMXBean.getCollectionUsage()
https://docs.oracle.com/javase/7/docs/api/java/lang/management/MemoryPoolMXBean.html#getCollectionUsage()

[pshipton]

@DanHeidinga I note there are new changes pushed.

[pshipton]

@LinHu2016 is this ready for re-review?

[LinHu2016]

@pshipton yes, the new update is ready for reviewing.

[pshipton]

@DanHeidinga fyi

[pshipton]

I don't expect this is going to be ready for the 0.15 release.

[pshipton]

Getting late to put into the 0.17 release, moving forward again.

[pshipton]

@DanHeidinga any plans to review this before the 0.18 release, or should it be moved to the next?

[DanHeidinga]

Will try and get through it this week (and apologies on the delay here)

[DanHeidinga]

@LinHu2016 Can you rebase this so it only includes your changes?

[DanHeidinga]

@LinHu2016 Can you rebase this so it only includes your changes?

[LinHu2016]

@LinHu2016 Can you rebase this so it only includes your changes?

the branch has been rebased with the latest master.

[LinHu2016]

update copyright to 2020

[DanHeidinga]

lgtm

[DanHeidinga]

Jenkins test sanity zlinux jdk8

[DanHeidinga]

Jenkins test extended zlinux jdk11

[DanHeidinga]

Jenkins test extended zlinux jdk11

[DanHeidinga]

Relaunched the extended testing as it failed. @LinHu2016 If it fails again, can you rebase to the latest and we'll rerun the builds?