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Posted to users@httpd.apache.org by Massimiliano De Ruosi <ma...@uniud.it> on 2013/09/02 10:46:09 UTC
[users@httpd] server-status page: meaning of "W" in multitier architecture
Hello,
I'm using Apache (2.2.16-6) as a frontend in a multitier stack: Apache
contacts load balancer (on port:9000) using a proxy directive:
RewriteRule ^/(.*) http://localhost:9000/(backend foo)/$1 [P]
I'm using numbers 1-6 to distinct different times in request/response life:
Client --1-> Apache --2-> Load Balancer --3-> Backend
Client <-6-- Apache <-5-- Load Balancer <-4-- Backend
Looking at server-status page, I cant understand the "scope" of
scoreboard key: "W" (Sending Reply): it refers only to sending reply
to client (6), or the entire process of contacting backend, waiting
for response, and sending it to client (2+3+4+5+6), or maybe other?
Searching in Apache docs I did't find useful information: maybe you
can point me to the correct documentation?
Thank you,
Massimiliano De Ruosi
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Re: [users@httpd] server-status page: meaning of "W" in multitier architecture
Posted by Tom Evans <te...@googlemail.com>.
On Tue, Sep 3, 2013 at 7:34 AM, Massimiliano De Ruosi
<ma...@uniud.it> wrote:
> Now I understand, thank you.
>
> Any suggestion about profiling a request using mod_proxy as a reverse proxy?
> Reading mod_proxy documentation I didn't find a useful solution (except
> lowering Timeout/ProxyTimeout to get some information in error log, but I
> was searching for a less "disruptive" profiling procedure).
tcpdump/wireshark can be useful in examining timings, hop-by-hop
headers and so on. It depends what you are trying to do.
Cheers
Tom
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Re: [users@httpd] server-status page: meaning of "W" in multitier
architecture
Posted by Massimiliano De Ruosi <ma...@uniud.it>.
Now I understand, thank you.
Any suggestion about profiling a request using mod_proxy as a reverse
proxy? Reading mod_proxy documentation I didn't find a useful solution
(except lowering Timeout/ProxyTimeout to get some information in error
log, but I was searching for a less "disruptive" profiling procedure).
Thank you again,
Massimiliano De Ruosi
Quoting Eric Covener <co...@gmail.com>:
>> Looking at server-status page, I cant understand the "scope" of scoreboard
>> key: "W" (Sending Reply): it refers only to sending reply to client (6), or
>> the entire process of contacting backend, waiting for response, and sending
>> it to client (2+3+4+5+6), or maybe other?
>
> It's counterintuitive, but W is used as soon as mod_proxy gets control
> (so just before it contacts the backend) until all of the response is
> forwarded. It really just means the configured "handler" has been
> entered and has not completed.
>
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> To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
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>
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Re: [users@httpd] server-status page: meaning of "W" in multitier architecture
Posted by Eric Covener <co...@gmail.com>.
> Looking at server-status page, I cant understand the "scope" of scoreboard
> key: "W" (Sending Reply): it refers only to sending reply to client (6), or
> the entire process of contacting backend, waiting for response, and sending
> it to client (2+3+4+5+6), or maybe other?
It's counterintuitive, but W is used as soon as mod_proxy gets control
(so just before it contacts the backend) until all of the response is
forwarded. It really just means the configured "handler" has been
entered and has not completed.
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