[KAFKA-12804] In-Memory state store backed by InMemoryKeyValueStore is slow due to synchronizing reads/writes using a single lock.

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.6.2
• Component/s: streams
• Labels: performance pull-request-available
• Flags: Patch
• Assignee: Ki Lok Wong
• Reporter: Ki Lok Wong
• Created: 18/May/21 02:41
• Updated: 18/May/21 03:45

Description

Default In-Memory state store (InMemoryKeyValueStore) uses TreeMap as the backing map implementation.  Read/write methods such as get() and put() are synchronized on the same lock hence significantly reducing multi-thread performance.

https://github.com/a0x8o/kafka/blob/f834be5e73e46805b29df9845bf09be98f91fc09/streams/src/main/java/org/apache/kafka/streams/state/internals/InMemoryKeyValueStore.java#L78