Re: mod_proxy_ajp failed to connect infrequently

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Hi All.

The error_log (debug) is attached.

I understood "(120006) error" means Apache wasn't able to receive the headers of the response from the backend server.
But I don't know why the headers didn't return and I want any opinions about the reason.
Please teach me how to know the problem.

Best regards,


(2010/10/12 11:07), Kikuchi Yu wrote:
Thanks for getting back to me.

 > Could it be a timeout while waiting for the reply? Add "%D" to your LogFormat and check, how long those requests take.

The following is an Apache's access_log when the HTTP 503 error occured.
It seems the request took only "42ms" so I think it's not because of a timeout.

xxx.xxx.xxx.xxx - - [09/Aug/2010:03:38:32 +0900] "GET /api/alive.jsp HTTP/1.1" 503 2366 0 42324

 > I didn't understand the "the errors disappeared instead of cping/cpong retry occurrence" part of your question.

I'm sorry I'm not good at using English well.

It's my understanding that:
1. "ping" option gets Apache to check the connection to the backend.
2. If the first CPing/CPong check doesn't succeed, it will reestablish a new connection to the backend and run one more
CPing/CPong.

When I set "ping=1" option to ProxyPass directive, Apache failed the first CPing/CPong check, but succeeded at
connecting to backend by the second CPing/CPong.
So HTTP 500/503 error didn't occur.

I wonder if the connection will break instantaneously(within 1 second).
Would you give me any comments about this phenomenon?


(2010/10/08 20:19), Rainer Jung wrote:
On 08.10.2010 09:33, Yu Kikuchi wrote:
My environment is Apache 2.2.11 and JBoss AS 5.0.0.
There were no messages in JBoss's access log when the error occured.

I had changed the setting to use "mod_proxy_http" the day before yesterday,
then not HTTP 503 error but 502 error occured.
Are anybody onto something about this error?

Are there any ideas to pursue the exact cause of it?


(2010/10/07 18:50), Yu Kikuchi wrote:
Hello.

Apache wrote such as following messages into error_log and returned HTTP 500/503 error infrequently.

[error] (104)Connection reset by peer: ajp_ilink_receive() can't receive header
[error] ajp_read_header: ajp_ilink_receive failed
[error] (120006)APR does not understand this error code: proxy: read response failed from xxx.xxx.xxx.xxx:8009
(xxx.xxx.xxx.xxx)

I have installed Apache and JBoss Application Server into the same server.
I suspected mod_proxy_ajp caused the errors because JBoss hasn't logged any messages and left indications of abort.

After the setting of "ping" options, the errors disappeared instead of cping/cpong retry occurrence. Exactly:

---------------------------------------------------
<Location /test>
ProxyPass ajp://xxx.xxx.xxx.xxx:8009/test ping=1
</Location>
---------------------------------------------------

I examine prior occurrences, but nobody told about the cause of this phenomenon.
Does anybody tell me why the errors came up?

Could it be a timeout while waiting for the reply? Add "%D" to your LogFormat and check, how long those requests take.

I didn't understand the "the errors disappeared instead of cping/cpong retry occurrence" part of your question.

Regards,

Rainer

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[Wed Oct 27 09:58:23 2010] [debug] mod_proxy_ajp.c(45): proxy: AJP: canonicalising URL //xxx.xxx.19.40:8009/api/alive.jsp
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(1489): [client xxx.xxx.19.33] proxy: ajp: found worker ajp://xxx.xxx.19.40:8009/api for ajp://xxx.xxx.19.40:8009/api/alive.jsp
[Wed Oct 27 09:58:23 2010] [debug] mod_proxy.c(993): Running scheme ajp handler (attempt 0)
[Wed Oct 27 09:58:23 2010] [debug] mod_proxy_http.c(1910): proxy: HTTP: declining URL ajp://xxx.xxx.19.40:8009/api/alive.jsp
[Wed Oct 27 09:58:23 2010] [debug] mod_proxy_ajp.c(626): proxy: AJP: serving URL ajp://xxx.xxx.19.40:8009/api/alive.jsp
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(1991): proxy: AJP: has acquired connection for (xxx.xxx.19.40)
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(2047): proxy: connecting ajp://xxx.xxx.19.40:8009/api/alive.jsp to xxx.xxx.19.40:8009
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(2145): proxy: connected /api/alive.jsp to xxx.xxx.19.40:8009
[Wed Oct 27 09:58:23 2010] [debug] ajp_header.c(224): Into ajp_marshal_into_msgb
[Wed Oct 27 09:58:23 2010] [debug] ajp_header.c(290): ajp_marshal_into_msgb: Header[0] [Host] = [xxx.xxx.19.40]
[Wed Oct 27 09:58:23 2010] [debug] ajp_header.c(290): ajp_marshal_into_msgb: Header[1] [Connection] = [Close]
[Wed Oct 27 09:58:23 2010] [debug] ajp_header.c(430): ajp_marshal_into_msgb: Done
[Wed Oct 27 09:58:23 2010] [debug] mod_proxy_ajp.c(264): proxy: APR_BUCKET_IS_EOS
[Wed Oct 27 09:58:23 2010] [debug] mod_proxy_ajp.c(269): proxy: data to read (max 8186 at 4)
[Wed Oct 27 09:58:23 2010] [debug] mod_proxy_ajp.c(284): proxy: got 0 bytes of data
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(1801): proxy: grabbed scoreboard slot 0 in child 25347 for worker ajp://xxx.xxx.19.40:8009/
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(1820): proxy: worker ajp://xxx.xxx.19.40:8009/ already initialized
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(1914): proxy: initialized single connection worker 0 in child 25347 for (xxx.xxx.19.40)
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(1801): proxy: grabbed scoreboard slot 2 in child 25347 for worker ajp://xxx.xxx.19.40:8009/api
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(1820): proxy: worker ajp://xxx.xxx.19.40:8009/api already initialized
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(1914): proxy: initialized single connection worker 2 in child 25347 for (xxx.xxx.19.40)
[Wed Oct 27 09:58:23 2010] [error] ajp_read_header: ajp_ilink_receive failed
[Wed Oct 27 09:58:23 2010] [error] (120006)APR does not understand this error code: proxy: read response failed from xxx.xxx.19.40:8009 (xxx.xxx.19.40)
[Wed Oct 27 09:58:23 2010] [debug] proxy_util.c(2009): proxy: AJP: has released connection for (xxx.xxx.19.40)
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