[CASSANDRA-3578] Multithreaded commitlog

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 2.1 beta1
• Labels: performance
• Assignee: Benedict Elliott Smith
• Reporter: Jonathan Ellis

Authors

Benedict Elliott Smith

Reviewers

Jonathan Ellis

• Created: 06/Dec/11 04:42
• Updated: 16/Apr/19 09:32
• Resolved: 02/Dec/13 19:11

Description

Brian Aker pointed out a while ago that allowing multiple threads to modify the commitlog simultaneously (reserving space for each with a CAS first, the way we do in the SlabAllocator.Region.allocate) can improve performance, since you're not bottlenecking on a single thread to do all the copying and CRC computation.

Now that we use mmap'd CommitLog segments (CASSANDRA-3411) this becomes doable.

(moved from CASSANDRA-622, which was getting a bit muddled.)

Issue Links

• is depended upon by: CASSANDRA-3930 CommitLogSegment uses RandomAccessFile which doesnt have fadvice
• is duplicated by: CASSANDRA-5911 Commit logs are not removed after nodetool flush or nodetool drain
• relates to: CASSANDRA-9533 Make batch commitlog mode easier to tune