Many thanks to you all.
I am still trying to figure out the issue. Let me re-explain the
problem I experienced with some details.
The environment is Ubuntu 22.04, Apache2, ModPerl.
I run a Http::request with LWP::UserAgent, the server receives
the request and starts to process it.
But it takes much longer due to a stalled SFTP call to the remote
server, the Apache server timeout and sends back failure,
meanwhile,*the server actually is still trying to process this
request*.
On the calling side, after receiving the failure status, it
initiates another http::request and the load balancer redirects
this call to another server for processing.
It turns out this same http::request is processed twice.
On my production server the timeout happens at 300 seconds mark.
On my QA and Dev server, the timeout happens at 600 seconds. I
have not changed anything on my production server yet.
But on my QA and DEV servers, I have tried to change Timeout in
apache2.conf, have tried to add Timeout to the virtualhost
config, also have tried to add SetPerlEnv MOD_PERL_TIMEOUT to the
virtualhost config, none of them change the timeout behavior of
my QA and DEV servers.
So what exactly controls the Timeout? I am totally lost.
Cheers,
Joe
On Wed, Apr 23, 2025 at 5:17 PM Mithun Bhattacharya
<mit...@gmail.com> wrote:
Okay agreed that is a valid time out basically it is saying
that a client has established tcp/ip connection but has not
put its request either a get put or a post
On Wed, Apr 23, 2025, 3:38 PM Joseph He
<joseph.he.2...@gmail.com> wrote:
On Apache2 doc, I found this. How does this timeout work?
It looks like it can only wait for 300 seconds before
failing a request.
https://httpd.apache.org/docs/2.0/mod/core.html#timeout
Description:
<https://httpd.apache.org/docs/2.0/mod/directive-dict.html#Description>
Amount of time the server will wait for certain events
before failing a request
Syntax:
<https://httpd.apache.org/docs/2.0/mod/directive-dict.html#Syntax>
|TimeOut seconds|
Default:
<https://httpd.apache.org/docs/2.0/mod/directive-dict.html#Default>
|TimeOut 300|
Context:
<https://httpd.apache.org/docs/2.0/mod/directive-dict.html#Context>
server config, virtual host
Status:
<https://httpd.apache.org/docs/2.0/mod/directive-dict.html#Status>
Core
Module:
<https://httpd.apache.org/docs/2.0/mod/directive-dict.html#Module>
core
The |TimeOut| directive currently defines the amount of
time Apache will wait for three things:
1. The total amount of time it takes to receive a GET
request.
2. The amount of time between receipt of TCP packets on
a POST or PUT request.
3. The amount of time between ACKs on transmissions of
TCP packets in responses.
We plan on making these separately configurable at some
point down the road. The timer used to default to 1200
before 1.2, but has been lowered to 300 which is still
far more than necessary in most situations. It is not set
any lower by default because there may still be odd
places in the code where the timer is not reset when a
packet is sent.
On Wed, Apr 23, 2025 at 3:07 PM Mithun Bhattacharya
<mit...@gmail.com> wrote:
You configure timeout at the client side. Apache is
at the server side. Server doesn't have a concept of
time it could take days to run and not care.
mod_perl code is where you are sending the http
return status to make sure the client doesn't timeout
waiting for the server to respond.
On Wed, Apr 23, 2025, 2:19 PM Joseph He
<joseph.he.2...@gmail.com> wrote:
Thanks, all.
Is that Apache timeout controlled by its
configuration "Timeout"?
I don't think it has anything to do with modPerl.
Am I missing something?
Thanks.
On Wed, Apr 23, 2025 at 1:41 PM Mithun
Bhattacharya <mit...@gmail.com> wrote:
Timeout happens because of how we handle the
request. Timeout is basically no response
came back. Why that happens is because we
think we want to have a correct response.
Unfortunately for long running requests the
correct response shouldn't be via http
response code or we face situations like
this. Instead reply with a 200 OK immediately
and then provide correct status in the
message body. Once a response code/header has
been sent timeout won't trigger and you could
potentially hold the connection for hours
without a problem.
On Wed, Apr 23, 2025, 9:32 AM Andreas Mock
<andreas.m...@web.de> wrote:
Hi Joseph,
your description is very vague, so can
only answer on some assumptions:
It sounds like a timeout is fired somewhere.
Best advice in these situations: Log as
many steps as you can. Keep your
eyes open on TCP/IP and higher level
timeouts.
Declare only ONE instance responsible for
a retry: Either the app server
calling the dispatcher with several tries
or the dispatcher trying for
himself. Not both.
Best regards
Andreas
Am 23.04.2025 um 16:21 schrieb Joseph He:
> All, good day.
>
> Here is the issue I have.
> My entire application is running on
ModPerl/Apache environment.
> I send Http::Request with data load
from my App server to a dispatch
> server thru LWP::UserAgent, I set the
timeout 600 seconds.
>
> The dispatch server is supposed to
manipulate the data and send the
> data to an external SFTP server.
Because the SFTP can fail, it will
> keep trying up to 4 times with 30
seconds sleep in case that SFTP
> connection fails.
>
> Recently, I found that I uploaded the
file twice sometimes. I figured
> out the root cause is that my Dispatch
server returns 'failure' at 6
> minutes while it keeps trying to do the
SFTP. The App server
> received HTTP::Response with error
status so it issued another call to
> send data. It turns out I uploaded the
identified file twice.
>
> Anybody has this sort of experience?
Why does the dispatch server
> return 'error' while it still processes
the data?
>
> Thanks a lot,
> Joseph
>
