[PROTON-659] if protons internal buffer gets large, performance can suffer

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: proton-0.7
• Component/s: proton-c
• Labels: perf
• Assignee: Andrew Stitcher
• Reporter: Gordon Sim
• Created: 04/Sep/14 13:38
• Updated: 22/Feb/18 15:50

Description

In doing some performance investigations using qpid::messaging over 1.0, in particular as message size got larger, I saw much lower throughput and lots of cpu used. From callgrind it looked like this was from shuffliing up the buffer in pn_dispatcher_output. Because of the threading in qpid::messaging, it was possible for the application to generate too much output using the top-half of the engine API before the IO was done for the bottom half. Fixing that in qpid:messaging improved performance.

There may perhaps be something that proton could do to make users more aware of this (e.g. a log message if the buffer exceeds a certain size? or just documentation?)

Issue Links

• is related to: PROTON-1687 Improve efficiency of the transport output buffer