[KUDU-1777] glog drop_log_memory causes a lot of IO to log dir

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Duplicate
• Affects Version/s: 1.1.0
• Fix Version/s: n/a
• Component/s: util
• Target Version/s: 1.2.0
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 01/Dec/16 06:34
• Updated: 05/Dec/16 03:37
• Resolved: 05/Dec/16 03:37

Description

glog is configured by default to call posix_fadvise with DONTNEED every time it flushes, and also configured such that any WARN or above causes such a flush. Every such fadvise call generates new IO to the log directory, journal commits, etc, and I think this may be affecting latency and stability adversely.

Issue Links

• relates to: KUDU-695 contention on glog disk can block reactor threads