branch-4.1: [fix](fe) Avoid blocking external meta cache refresh on slow miss load #64705#64791
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#64705) ### What problem does this PR solve? Issue Number: N/A Related PR: N/A Problem Summary: This PR avoids blocking external meta cache invalidation on slow miss loads in FE. Previously, `MetaCacheEntry` relied on Caffeine's synchronous loading path for cache misses. When an external metadata loader became slow, operations that invalidate the same cache, such as `REFRESH CATALOG` and the corresponding replay path, could wait on the slow load and block the replay-related invalidation flow. Implementation summary: - Keep the existing `LoadingCache` to preserve current hit-path behavior and `refreshAfterWrite` support. - Add a manual miss-load path behind a new FE config switch, using `getIfPresent()` instead of synchronous `LoadingCache.get()` for misses. - Deduplicate concurrent miss loads with striped locks inside `MetaCacheEntry`. - Add an entry-level `invalidateGeneration` counter. Each invalidate increments the generation before clearing cache state. - Record the generation before a manual miss load, check it once before `put()`, and check it again after `put()`. If invalidation happens during the race window, the just-loaded value is removed so stale data is not kept in cache. - Keep null miss-load results uncached so the manual path does not attempt to put null into Caffeine. Configuration: - Add FE config `enable_external_meta_cache_manual_miss_load`, default `false`. - When it is `false`, `MetaCacheEntry` keeps the original synchronous Caffeine miss-load behavior. - When it is `true`, `MetaCacheEntry` uses the manual miss-load path plus `invalidateGeneration` protection. Scope and limitations: - This change applies to `MetaCacheEntry` used by external metadata cache paths in FE. It does not cover the legacy `MetaCache`. - `LegacyMetaCacheFactory` is intentionally not refactored in this PR. A follow-up PR will rework that path with `MetaCache`, and the legacy factory changes are left to that dedicated refactor. - The protection is designed for manual miss loads. It does not make Caffeine's asynchronous `refreshAfterWrite` reload generation-aware. - As a result, `refreshAfterWrite` is still preserved, but an async refresh result may still write back after an invalidate. That is an intentional trade-off in this version. - The new regression case is valuable as a reference and for suitable environments, but it may be skipped in standard CI because it depends on JDBC regression setup, FE debug points, and an external MySQL/JDBC environment. ### Release note None ### Check List (For Author) - Test - [ ] Regression test - [x] Unit Test - [x] 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 Manual test: 1. Reproduced the blocking path with `REFRESH CATALOG` against a JDBC external catalog and a debug point that sleeps in `PluginDrivenExternalTable.initSchema`. 2. Repeated the baseline scenario 5 times with `enable_external_meta_cache_manual_miss_load=false` and observed `REFRESH CATALOG` blocked for about 14s while `DESC` stayed slow. 3. Repeated the optimized scenario 5 times with `enable_external_meta_cache_manual_miss_load=true` and observed `REFRESH CATALOG` return within about 1s while `DESC` remained slow. 4. Added a regression case as a manual-test reference because its execution depends on JDBC regression environment and FE debug-point availability. Unit test: - `FE_UT_PARALLEL=1 ./run-fe-ut.sh --run org.apache.doris.datasource.metacache.MetaCacheEntryTest` - Behavior changed: - [x] Yes. Behavior change: - `REFRESH CATALOG` and the corresponding FE invalidation path are no longer blocked by slow external metadata miss loads in this `MetaCacheEntry` implementation. - Does this need documentation? - [x] No. - [ ] Yes. ### Check List (For Reviewer who merge this PR) - [ ] Confirm the release note - [ ] Confirm test cases - [ ] Confirm document - [ ] Add branch pick label
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FE Regression Coverage ReportIncrement line coverage |
yiguolei
approved these changes
Jun 25, 2026
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Cherry-picked from #64705