SOLR-17149: Fix backup/restore for large collections.

[psalagnac]

https://issues.apache.org/jira/browse/SOLR-17149

Description

A regression was introduced with SOLR-16879 that makes backup/restore failing when there are more than 5 shards per node.

Solution

Replace the bounded queue for async core admin tasks by an unbounded one.

Tests

No unit tests added.
Manually checked we don't have any tasks rejected by the executor.

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide

[gerlowskija]

Hi @psalagnac - this LGTM, generally.

The one thing missing IMO is some modifications to AbstractIncrementalBackupTest to cover the many-shards case. I took a stab at these locally and have code ready to share, put it looks like your branch isn't configured to allow others to push to it:

$ git push psalagnac SOLR-17149:SOLR-17149
Enumerating objects: 84, done.
Counting objects: 100% (84/84), done.
Delta compression using up to 28 threads
Compressing objects: 100% (32/32), done.
Writing objects: 100% (51/51), 13.84 KiB | 4.61 MiB/s, done.
Total 51 (delta 22), reused 0 (delta 0), pack-reused 0
remote: Resolving deltas: 100% (22/22), completed with 19 local objects.
To github.com:psalagnac/solr.git
 ! [remote rejected]         SOLR-17149 -> SOLR-17149 (**permission denied**)
error: failed to push some refs to 'github.com:psalagnac/solr.git'

If you're willing to accept my test changes, could you take a look at your branch settings and let me know when they're updated? Or alternatively, if you'd rather make the changes yourself, that's fine too.

[psalagnac]

@gerlowskija Not sure why you got denied. I already checked the "Allow edits and access to secrets by maintainers" box.

Can this be because of branch name case? (SOLR-17149 vs solr-17149)

[gerlowskija]

Gah - that must've been it! Thanks for catching my mistake. I've pushed my test-changes, and run 'test'+'check' locally. So I'll merge and backport. Thanks for the quick fix @psalagnac !

[psalagnac]

Thanks for the test. Looks good to me.