[OAK-6984] High read IO in compaction retry cycles

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.7.14, 1.8.0
• Component/s: segment-tar
• Labels: performance
• Epic Link: TarMK GC scalability
• Assignee: Michael Dürig
• Reporter: Michael Dürig
• Created: 27/Nov/17 11:00
• Updated: 30/Dec/17 09:06
• Resolved: 11/Dec/17 13:57

Description

We have seen unusual high read IO in compaction retry cycles in our longevity tests at Adobe.

Above picture shows the CPU utilisation during an online compaction run, which starts at 03:00. At about 03:22 CPU user time drops and CPU waiting for IO time increases. This point in time coincides with the start of the first retry cycle of compaction.