[jdk17u-dev] RFR: 8256811: Delayed/missed jdwp class unloading events [v4]

[Andrew John Hughes]

On Wed, 7 Sep 2022 09:54:02 GMT, Andrew Dinn <adinn at openjdk.org> wrote:

>> Backport of patch to fix class unloading event notification.
>> 
>> This backport was originally developed by @zhengyu123 and involved some minor changes to the original patch.
>> 
>> n.b. the original patch required a follow up fix (cf JDK-8290908) which also needs backporting after this has been included.
>
> Andrew Dinn has updated the pull request incrementally with one additional commit since the last revision:
> 
>   correct type

My impression from the bugs was that the code change itself is an improvement, and fewer events are missed, but it is difficult to get a reliable test which triggers class unloading and picks up all the events. I'm tending towards going ahead with backporting the four existing patches, but I expect you have a better idea of the risk than I do.

If we do this now, it'll be targeted for the January release so we still have some time to add further follow-up fixes or even revert in 17u. I don't get the impression that the main patch is flawed enough to warrant being reverted in trunk, but if we want to be extra safe, we could wait until some time after OpenJDK 20 is released next March.

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PR: https://git.openjdk.org/jdk17u-dev/pull/635