## What changes were proposed in this pull request?
Address SPARK-26548, in Spark 2.4.0, the CacheManager holds a write lock while computing the executedPlan for a cached logicalPlan. In some cases with very large query plans this can be an expensive operation, taking minutes to run. The entire cache is blocked during this time. This PR changes that so the writeLock is only obtained after the executedPlan is generated, this reduces the time the lock is held to just the necessary time when the shared data structure is being updated.
gatorsmile and cloud-fan - You can committed patches in this area before. This is a small incremental change.
## How was this patch tested?
Has been tested on a live system where the blocking was causing major issues and it is working well.
CacheManager has no explicit unit test but is used in many places internally as part of the SharedState.
Closes#23469 from DaveDeCaprio/optimizer-unblocked.
Lead-authored-by: Dave DeCaprio <daved@alum.mit.edu>
Co-authored-by: David DeCaprio <daved@alum.mit.edu>
Signed-off-by: gatorsmile <gatorsmile@gmail.com>
a17851cb95