Shut down ForkJoinPool in KMeansTrainer

[ylwu-amzn]

Describe the bug

KMeansTrainer will create ForkJoinPool to train KMeans model in parallel, code link : https://github.com/oracle/tribuo/blob/main/Clustering/KMeans/src/main/java/org/tribuo/clustering/kmeans/KMeansTrainer.java#L284-L293

But the ForkJoinPool doesn't shutdown when training complete. As KMeansTrainer doesn't set keepAliveTime for ForkJoinPool, the default keep alive time is 60 seconds. Refer to https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/ForkJoinPool.html

keepAliveTime - the elapsed time since last use before a thread is terminated (and then later replaced if needed). For the default value, use 60, TimeUnit.SECONDS.

It's risky when kmeans training requests come in high volume in short time (<60seconds).

[ylwu-amzn]

Close this issue as PR #224 merged

[ylwu-amzn]

We plan to release a new version of OpenSearch/ml-commons soon, maybe in next 2 weeks. Is it possible you release 4.2.1 including this fix quckly?

[Craigacp]

I expect we can get it tagged in the repo next week, however I'm not in control of the push to Maven Central so I don't know if that will happen within two weeks.

[ylwu-amzn]

Thanks, I see you add release note for 4.2.1 , 2338b10, hope that can be released soon.

[Craigacp]

Yeah, it'll take a little while longer unfortunately as I need to tag OLCUT with a bumped version of jackson, push that to Maven Central and then have Tribuo depend on that (both in main and v4.2.X-release-branch).

[ylwu-amzn]

@Craigacp any update on the new version release for 4.2.1?

[Craigacp]

Working on it. Should have OLCUT tagged by the end of the week, then I can work on Tribuo.

[ylwu-amzn]

Sorry to ask again, any progress for 4.2.1 release?

[Craigacp]

OLCUT 5.2.1 has been tagged however last week we started rolling out a new internal process for pushing libraries to Maven Central for open source projects and so our releases got caught up in that. I've made the request, and I'm hopeful it will happen soon. Once it does I'll bump the version in Tribuo, merge that to the v4.2.X-release-branch, tag the new version and request that is pushed to Maven Central.

Once the bugs are worked out in the new release process it should be faster and I'll have more understanding of when binaries will make it to Maven Central (so can plan these things better), but we're one of the first projects to go through the new process so there are inevitable issues.

[ylwu-amzn]

Totally understand. Thanks a lot @Craigacp !

[Craigacp]

Tribuo 4.2.1 is now on Maven Central - https://search.maven.org/artifact/org.tribuo/tribuo-all/4.2.1/pom.