[HTRACE-297] htraced: avoid serializing spans to json unless TRACE logging is enabled

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0
• Fix Version/s: 4.1
• Component/s: htraced
• Target Version/s: 4.1
• Assignee: Colin McCabe
• Reporter: Colin McCabe
• Created: 12/Nov/15 20:46
• Updated: 13/Nov/15 07:45
• Resolved: 13/Nov/15 07:36

Description

We have been unconditionally serializing spans to JSON, but only logging them when TRACE logging is enabled. Profiling has revealed that this is a CPU bottleneck. Let's put "if" statement guards around the log messages to avoid doing this serialization unless it is really useful.