[IGNITE-14893] Bug in GridCacheWriteBehindStore Flusher thread lookup

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.8, 2.7.5, 2.7.6, 2.9, 2.8.1, 2.10, 2.9.1
• Fix Version/s: 2.12
• Component/s: cache
• Release Note: Fixed bug in GridGainWriteBehindStore flushers thread lookup.
• Ignite Flags: Docs Required, Release Notes Required
• Assignee: Ilya Korol
• Reporter: Mike W
• Reviewer: Vyacheslav Koptilin
• Created: 10/Jun/21 14:11
• Updated: 06/Jul/21 11:00
• Resolved: 05/Jul/21 09:22

Description

There's a bug in GridCacheWriteBehindStore in the flusher method.

https://github.com/apache/ignite/blob/master/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/store/GridCacheWriteBehindStore.java#L674

The logic states there that if flush thread count is not a power of 2, then perform this math, which is not guaranteed to return a positive number.

idx = ((h = key.hashCode()) ^ (h >>> 16)) % flushThreadCnt

For example, if you pass this string as a key, it returns a negative number:
accb2e8ea33e4a89b4189463cacc3c4e

and then throws an array out of bounds exception when looking up the thread.

http://apache-ignite-developers.2346864.n4.nabble.com/IndexOutOfBoundsException-in-GridCacheWriteBehindStore-Flusher-thread-lookup-IGNITE-14893-tp52827.html

Issue Links

• is duplicated by: IGNITE-14892 Bug in GridCacheWriteBehindStore Flusher thread lookup
• is duplicated by: IGNITE-14898 IndexOutOfBoundException in flusher selection logic in GridCacheWriteBehindStore
• links to: GitHub Pull Request #9177