ProxyTimeout

Hello,

In a Reverse Proxy server, what is the relation of Apache "TimeOut" and "ProxyTimeout"? Can someone shed some lights on it?

Thx, Q.Xie




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Re: ProxyTimeout

On Wed 19 Aug 2009, Qingshan Xie wrote:
> In a Reverse Proxy server, what is the relation of Apache "TimeOut"
> and "ProxyTimeout"? =A0Can someone shed some lights on it?

TimeOut aborts a request if the client/browser takes too long to send or=20
receive data. ProxyTimeout aborts a connection to the backend if it is=20
not responding.

Timeout ProxyTimout
browser <===========3D> proxy <=========
=======3D> backend

Torsten

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Re: ProxyTimeout

Thanks for your quick reply.

I am wondering what will happen in the case below,

Timeout ProxyTimout
browser <===========> proxy <===============> backend

Timeout = 300 sec and ProxyTimeout = 600 sec,

If backend process longer than 5 min, what will happen?
From the observation of my server, the whole HTTP session won't be terminated till 10 min. I am not sure why since the front connection should be terminated in 5 min?

Thx, Q.Xie


----- Original Message ----
From: Torsten Foertsch
To: users@httpd.apache.org
Cc: Qingshan Xie
Sent: Wednesday, August 19, 2009 12:23:29 PM
Subject: Re: [users@httpd] ProxyTimeout

On Wed 19 Aug 2009, Qingshan Xie wrote:
> In a Reverse Proxy server, what is the relation of Apache "TimeOut"
> and "ProxyTimeout"? Can someone shed some lights on it?

TimeOut aborts a request if the client/browser takes too long to send or
receive data. ProxyTimeout aborts a connection to the backend if it is
not responding.

Timeout ProxyTimout
browser <===========> proxy <===============> backend

Torsten

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Re: ProxyTimeout

On Wed, Aug 19, 2009 at 4:14 PM, Qingshan Xie wrote:
> Thanks for your quick reply.
>
> I am wondering what will happen in the case below,
>
> =A0 =A0 =A0 =A0 =A0 Timeout =A0 =A0 =A0 =A0 =A0 =A0 ProxyTimout
> browser <===========3D> proxy <=======3D=
========> backend
>
> =A0Timeout =3D 300 sec and ProxyTimeout =3D 600 sec,
>
> If backend process longer than 5 min, what will happen?
> From the observation of my server, =A0the whole HTTP session won't be ter=
minated till 10 min. =A0I am not sure why since the front connection should=
be terminated in 5 min?

Timeouts only apply while Apache is waiting for something to happen.
Apache isn't waiting on anything from the browser, so there's no 5min
timeout in effect.

--=20
Eric Covener
covener@gmail.com

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Re: ProxyTimeout

Qingshan Xie wrote:
> Thanks for your quick reply.
>
> I am wondering what will happen in the case below,
>
> Timeout ProxyTimout
> browser <===========> proxy <===============> backend
>
> Timeout = 300 sec and ProxyTimeout = 600 sec,
>
> If backend process longer than 5 min, what will happen?
>>From the observation of my server, the whole HTTP session won't be terminated till 10 min. I am not sure why since the front connection should be terminated in 5 min?
>
I am not entirely sure, since I have not examined the Apache code
itself, but in my understanding, the "Timeout" parameter, precisely and
only, applies when Apache is waiting for something from the browser, and
the browser is not sending it.
For example :
- the browser creates a TCP connection to the Apache server, on port 80.
- Apache accepts this TCP connection
- Apache now waits for the browser to send a request over that connection
- the browser, for whatever reason, is not sending the request (or not a
complete request), within "Timeout" seconds

Then the Timeout applies. Apache will close the connection, because it
is not getting the expected request over that connection.
This avoids a kind of DOS attack, whereby clients could open many
connections to Apache, then not send any request, blocking Apache forever.

So it does /not/ apply when it is Apache that should send something to
the browser, and does not send it. In that last case, what may happen
is that /the browser/ times out, because Apache takes too long to
respond. In my experience, this browser timeout is several minutes
(3..5 ?). I don't know if this timeout is adjustable in the usual browsers.




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Re: ProxyTimeout

Thanks guys for your help. Think I may not describe my question clearl=
y. My question is, in the case of Timeout=3D5 min but ProxyTimeout=3D10 mi=
n in a Reverse Proxy Server, if the backend response is over 10 min, when t=
he connection will be closed, 5 min or 10 min? Thanks again.=0AQ.Xie=
----- Original Message ----=0AFrom: Andr=E9 Warnier com>=0ATo: users@httpd.apache.org=0ASent: Wednesday, August 19, 2009 2:00:2=
6 PM=0ASubject: Re: [users@httpd] ProxyTimeout Qingshan Xie wrote:=0A>=
Thanks for your quick reply. =0A> I am wondering what will happen in the c=
ase below, =0A> Timeout ProxyTimout=0A> browser <=3D=
==========> proxy <=============
===3D> backend=0A> =0A> Timeout =3D 300 sec and ProxyTimeout =3D 600 s=
ec, =0A> If backend process longer than 5 min, what will happen? =0A>> Fro=
m the observation of my server, the whole HTTP session won't be terminated=
till 10 min. I am not sure why since the front connection should be termi=
nated in 5 min? =0A> =0AI am not entirely sure, since I have not examined =
the Apache code itself, but in my understanding, the "Timeout" parameter, p=
recisely and only, applies when Apache is waiting for something from the br=
owser, and the browser is not sending it.=0AFor example :=0A- the browser c=
reates a TCP connection to the Apache server, on port 80.=0A- Apache accept=
s this TCP connection=0A- Apache now waits for the browser to send a reques=
t over that connection=0A- the browser, for whatever reason, is not sending=
the request (or not a complete request), within "Timeout" seconds The=
n the Timeout applies. Apache will close the connection, because it is not=
getting the expected request over that connection.=0AThis avoids a kind of=
DOS attack, whereby clients could open many connections to Apache, then no=
t send any request, blocking Apache forever. So it does /not/ apply wh=
en it is Apache that should send something to the browser, and does not sen=
d it. In that last case, what may happen is that /the browser/ times out, =
because Apache takes too long to respond. In my experience, this browser t=
imeout is several minutes (3..5 ?). I don't know if this timeout is adjust=
able in the usual browsers. =0A---------------------------------=
------------------------------------=0AThe official User-To-User support fo=
rum of the Apache HTTP Server Project.=0ASee serslist.html> for more info.=0ATo unsubscribe, e-mail: users-unsubscribe@h=
ttpd.apache.org=0A " from the digest: users-digest-unsubscribe@httpd.apa=
che.org=0AFor additional commands, e-mail: users-help@httpd.apache.org=0A=


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Re: ProxyTimeout

On Wed, Aug 19, 2009 at 5:55 PM, Qingshan Xie wrote:
> Thanks guys for your help.
>
> Think I may not describe my question clearly. =A0My question is, in the c=
ase of Timeout=3D5 min but ProxyTimeout=3D10 min in a Reverse Proxy Server,=
if the backend response is over 10 min, when the connection will be closed=
, 5 min or 10 min?

The timeouts apply to single network operation, there is no end-to-end
timer running.

If Apache has to wait 10 minutes for a single read from the origin
server to complete, it will timeout. An error response will be sent
to the client, if he hasn't closed his own end of the connection by
then.

--=20
Eric Covener
covener@gmail.com

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Re: ProxyTimeout

On Wed 19 Aug 2009, Qingshan Xie wrote:
> Think I may not describe my question clearly. =A0My question is, in the
> case of Timeout=3D5 min but ProxyTimeout=3D10 min in a Reverse Proxy
> Server, if the backend response is over 10 min, when the connection
> will be closed, 5 min or 10 min?

The manual at http://httpd.apache.org/docs/2.2/mod/core.html#timeout=20
answers your question very clearly. Timeout applies to single IO=20
operations.

Torsten

=2D-=20
Need professional mod_perl support?
Just hire me: torsten.foertsch@gmx.net

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