github-actions[bot] commented on code in PR #65409:
URL: https://github.com/apache/doris/pull/65409#discussion_r3551908813
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fe/fe-core/src/main/java/org/apache/doris/datasource/ExternalDatabase.java:
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@@ -120,12 +120,19 @@ public void resetMetaToUninitialized() {
LOG.debug("resetToUninitialized db name {}, id {}, isInitializing:
{}, initialized: {}",
this.name, this.id, isInitializing, initialized, new
Exception());
}
+ MetaCache<T> cacheToInvalidate = null;
synchronized (this) {
this.initialized = false;
this.lowerCaseToTableName = Maps.newConcurrentMap();
- if (metaCache != null) {
- metaCache.invalidateAll();
- }
+ cacheToInvalidate = metaCache;
+ }
+ // Invalidate cache outside the synchronized block to avoid deadlock:
+ // ExternalDatabase monitor -> Caffeine internal locks (REFRESH path)
+ // vs Caffeine internal locks -> ExternalDatabase monitor (cache
loader path).
+ // Do NOT null metaCache here — callers dereference it outside the
monitor
+ // after makeSureInitialized() returns (e.g. getTableNullable,
getTableNamesWithLock).
+ if (cacheToInvalidate != null) {
+ cacheToInvalidate.invalidateAll();
Review Comment:
Moving the invalidation outside the monitor fixes the Caffeine lock
inversion, but this ordering now publishes `initialized = false` while the old
`metaCache` is still live and not yet invalidated. A query thread can enter
`makeSureInitialized()` in this window, see `initialized == false`, call
`buildMetaCache()` as a no-op because `metaCache` is non-null, set `initialized
= true`, and then `getTableNullable()`/`getTableNamesWithLock()` can read the
old cache before this line invalidates it. That means `REFRESH DATABASE` can
still allow a new reader to plan from stale table metadata during the refresh.
Please publish a fresh cache/snapshot under the monitor before invalidating the
old one, or otherwise keep readers from reinitializing until the old cache has
been invalidated outside the monitor.
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