[httperf] connection failed with unexpected error 49

Martin Arlitt arlitt at hpl.hp.com
Wed Jun 14 06:40:16 PDT 2006

hi Stefan

I don't remember encountering 'error 49' before, but I haven't used
httperf on OS X before either.

without knowing any details about the experiment you are conducting, I can
only speculate as to the cause.  It might be the case that you are
exhausting all of the TCP ports available to httperf; i.e., httperf is
initiating the active close, thus putting the ports into the TIME_WAIT
state; depending on the rate you are attempting to create new TCP
connections, you could quickly exhaust all of the TCP ports, and httperf
will not be able to open any new connections until TIME_WAIT expires.

there are several things you can do.  first, if you are not using the
--hog option, that could make more TCP ports available to httperf.
depending on the connection rate, this may enable you to continue to
generate new connections while waiting for older connections to exit the
TIME_WAIT state and become available for use again.

second, you may have to modify some system parameters/settings to enable a
user process to utilize more file descriptors.

third, you can investigate whether it is possible on OS X to reduce the
time that old connections stay in the TIME_WAIT state (this should not be
done in general, i.e., for machines connected to the Internet, but is ok
for experimental work).

I have used all of these on a linux client to enable httperf to generate
and sustain high connection rates; the details of how I set up the
linux client are described in Section 3.1.1 of "Understanding Web Server
Configuration Issues" in Software: Practice and Experience, Volume 34,
Issue 2, Pages 163-186, Feb. 2004.  That may or may not help you determine
how to configure your OS X client.


On Wed, 14 Jun 2006, Stefan Groschupf wrote:

> Hi,
> btw, a nice tool.
> However I note that I got bogus results if following error will
> reported:
> httperf: connection failed with unexpected error 49
> The network traffic stops and the request rate is much less than
> expected.
> What does this error mean? How to prevent this error?
> My test client is a dual core intel chip with OSX, httperf was
> builded via open darwin ports?
> Thank a lot of any hints.
> Stefan
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