[KUDU-710] CFileIterator::Scan spends 25% of its time copying Status

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Cannot Reproduce
• Affects Version/s: Private Beta
• Component/s: cfile, perf
• Target Version/s: Private Beta
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 16/Apr/15 15:09
• Updated: 04/May/15 16:56
• Resolved: 04/May/15 16:56

Description

I ran perf record on a TS running the "real world TPCH" benchmark, and saw a weird stack trace with CFileIterator::Scan -> memcpy(). This function doesn't really do any memcpy as far as I knew, so I digged a bit deeper. It looks like it's spending a lot of time memcpy()ing a Status object.

Seems like ultra low-hanging fruit for scan perf.