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From: Steve Zweep <Steve.Zweep@watchguard.com>
To: "dev@httpd.apache.org" <dev@httpd.apache.org>
Subject: RE: Question about async mod_proxy_wstunnel and threads
Thread-Topic: Question about async mod_proxy_wstunnel and threads
Thread-Index: AQHPoiW3eYiZqZoLd0ezAgxYocLRXJulFk+/
Date: Fri, 18 Jul 2014 02:44:54 +0000
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OK, I'll have a go at that tomorrow. I should note that it doesn't *always*=
 fail for me. However I haven't yet been able to predict when it will work =
and when it won't. I did run it earlier with trace7 logging and basically s=
aw no messages for the connections that were stalling. The trunk code I che=
cked out was quite recent, and I did confirm I had all the latest fixes in =
place.=0A=
=0A=
I'll send logs and annotations once I've collected them. Thanks Eric.=0A=
=0A=
- Steve=0A=
________________________________________=0A=
From: Eric Covener [covener@gmail.com]=0A=
Sent: July 17, 2014 9:15 PM=0A=
To: Apache HTTP Server Development List=0A=
Subject: Re: Question about async mod_proxy_wstunnel and threads=0A=
=0A=
I am having trouble seeing it mis-behave. w/ Async and AsyncDelay, I=0A=
am seeing the expected trace messages and when I look at backtraces of=0A=
httpd I can see zero threads in wstunnel . If I send a server msg, I=0A=
get it ASAP in the client -- and then I see 1 thread in poll for the=0A=
right couple of seconds=0A=
=0A=
Can you grab trace at e.g.=0A=
=0A=
LogLevel INFO proxy_wstunnel_module:trace8=0A=
=0A=
And annotate the timing a bit for what you do in the client?  Is it=0A=
possible you have an un-updated trunk from several weeks ago?  There=0A=
was an optimization put in and backed out that might have broke some=0A=
of these same things for a very short window.=0A=
=0A=
On Thu, Jul 17, 2014 at 2:09 PM, Steve Zweep <Steve.Zweep@watchguard.com> w=
rote:=0A=
> Hi=0A=
>=0A=
>=0A=
>=0A=
> I am prototyping a system in which we will have a large number of websock=
et=0A=
> connections between multiple clients and a server (potentially) behind=0A=
> mod_proxy_wstunnel. Currently I am testing a trunk build with the event m=
pm.=0A=
> With ProxyWebsocketAsync turned off, communication between client and ser=
ver=0A=
> works well except that an Apache thread is held open for each connection=
=0A=
> (which is expected). With ProxyWebsocketAsync enabled, these threads are =
no=0A=
> longer seen, again as expected. I see two issues though:=0A=
>=0A=
> 1.       While communication from client to server works well, unsolicite=
d=0A=
> messages from the server to clients seem to queue. If the client=0A=
> subsequently sends a message back to the server, the original message fro=
m=0A=
> the server is received. I would have expected the data from the server to=
=0A=
> generate an event resulting in immediate delivery.=0A=
>=0A=
> 2.       In attempts to debug this I experimented with=0A=
> ProxyWebsocketAsyncDelay. I observed that when this is used, the connecti=
ons=0A=
> never go into async mode. I.e. proxy_tunnel_pump() never returns SUSPENDE=
D.=0A=
> As a result I see the same thread usage as when ProxyWebsocketAsync is=0A=
> turned off. Is this expected behavior?=0A=
>=0A=
>=0A=
>=0A=
> Any insights into what is going on here would be helpful. I noticed that=
=0A=
> there have been a number of recent changes both to the event mpm and=0A=
> mod_proxy_wstunnel. Perhaps there are still some known issues with this=
=0A=
> code?=0A=
>=0A=
>=0A=
>=0A=
> Thanks=0A=
>=0A=
>=0A=
>=0A=
> - Steve=0A=
>=0A=
>=0A=
>=0A=
> -----------=0A=
>=0A=
> Steve Zweep | Senior Software Engineer=0A=
>=0A=
> WatchGuard Technologies, Inc. | www.watchguard.com=0A=
>=0A=
>=0A=
>=0A=
> 905.804.2143=0A=
>=0A=
> steve.zweep@watchguard.com=0A=
>=0A=
>=0A=
=0A=
=0A=
=0A=
--=0A=
Eric Covener=0A=
covener@gmail.com=0A=