Todd Lipcon created IMPALA-7534:
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Summary: Handle invalidation races in CatalogdMetaProvider cache
Key: IMPALA-7534
URL: https://issues.apache.org/jira/browse/IMPALA-7534
Project: IMPALA
Issue Type: Sub-task
Reporter: Todd Lipcon
There is a well-known race in Guava's LoadingCache that we are using for
CatalogdMetaProvider which we are not currently handling:
- thread 1 gets a cache miss and makes a request to fetch some data from the
catalogd. It fetches the catalog object with version 1 and then gets context
switched out or otherwise slow
- thread 2 receives an invalidation for the same object, because it has changed
to v2. It calls 'invalidate' on the cache, but nothing is yet cached.
- thread 1 puts back v1 of the object into the cache
In essence we've "missed" an invalidation. This is also described in this nice
post: https://softwaremill.com/race-condition-cache-guava-caffeine/
The race is quite unlikely but could cause some unexpected results that are
hard to reason about, so we should look into a fix.
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