xy720 opened a new pull request, #68141:
URL: https://github.com/apache/doris/pull/68141
### What problem does this PR solve?
Problem Summary:
Before this patch each MTMV kept two MTMVCache (cacheWithGuard /
cacheWithoutGuard) that held Nereids plan trees.
The lifetime of MTMVCache is same as the MTMV object, when these MTMVCaches
are at large scale (e.g. thousands of mtmv were created and refreshed, but they
were not dropped afterwards) may ocupy lots of FE heap space.
A heap-histogram check showing 72540 MTMVCache instances held ~30GB in FE
heap on the affected cluster.
This pr replace the origin MTMVCaches with Caffeine cache keyed by (mtmvId,
guarded), using maximumSize + expireAfterAccess so cold entries are evicted
under memory pressure instead of accumulating forever.
Initial config, all mutable via ADMIN SET FRONTEND CONFIG:
```
mtmv_cache_manage_num=3000,
expire_mtmv_cache_in_fe_second=86400,
mtmv_cache_hot_show_num=500.
```
Also support observability:
```
SHOW PROC '/mtmv_cache/stat' returns:
size / hitCount / missCount / evictionCount / loadFailureCount / hitRate
SHOW PROC '/mtmv_cache/hot' returns MtmvId / DbName / MvName / Guarded /
IdleMs
ordered by most-recently-accessed for MVs
```
### Release note
None
### Check List (For Author)
- Test <!-- At least one of them must be included. -->
- [x] Regression test
- [x] Unit Test
- [ ] Manual test (add detailed scripts or steps below)
- [ ] No need to test or manual test. Explain why:
- [ ] This is a refactor/code format and no logic has been changed.
- [ ] Previous test can cover this change.
- [ ] No code files have been changed.
- [ ] Other reason <!-- Add your reason? -->
- Behavior changed:
- [x] No.
- [ ] Yes. <!-- Explain the behavior change -->
- Does this need documentation?
- [x] No.
- [ ] Yes. <!-- Add document PR link here. eg:
https://github.com/apache/doris-website/pull/1214 -->
### Check List (For Reviewer who merge this PR)
- [ ] Confirm the release note
- [ ] Confirm test cases
- [ ] Confirm document
- [ ] Add branch pick label <!-- Add branch pick label that this PR should
merge into -->
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