[jira] [Created] (FLINK-15512) Refactor the mechanism of how to constructure the cache and write buffer manager shared across RocksDB instances

["Yun Tang (Jira)" <ji...@apache.org>]

Yun Tang created FLINK-15512:
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             Summary: Refactor the mechanism of how to constructure the cache and write buffer manager shared across RocksDB instances 
                 Key: FLINK-15512
                 URL: https://issues.apache.org/jira/browse/FLINK-15512
             Project: Flink
          Issue Type: Sub-task
          Components: Runtime / State Backends
            Reporter: Yun Tang
             Fix For: 1.10.0


FLINK-14484 introduce a {{LRUCache}} to share among RocksDB instances, so that the memory usage by RocksDB could be controlled well. However, due to the implementation and some bugs in RocksDB ([issue-6247|https://github.com/facebook/rocksdb/issues/6247]), we cannot limit the memory strictly.

The way to walk around this issue is to consider the buffer which memtable would overuse (1/2 write buffer manager size). By introducing this, the actual cache size for user to share is not the same as the managed off-heap memory or user configured memory.



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