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I am running:

Apache/2.2.15 (Unix) on CentOS release 6.6 (Final)

I am running a reverse proxy that forwards requests on to a tomcat server running on localhost:8080. My config looks like this:

<VirtualHost *:80>
....

  <Proxy *>
    Order deny,allow
    Allow from all
    AuthType Basic
    AuthName “Username/Password”
    AuthUserFile /etc/httpd/conf.d/users.auth
    Require valid-user
  </Proxy>

  Setenv proxy-nokeepalive 1
  Setenv proxy-sendcl 1
  Setenv proxy-initial-not-pooled 1
  SetEnv force-proxy-request-1.0 1

  ProxyPass /analytics http://localhost:8080/analytics disablereuse=on ttl=1 smax=0
  ProxyPassReverse /analytics http://localhost:8080/analytics

You can see I've chucked a whole load of stuff in there out of desperation - I've been trying to get this to work for several days.

Most of the queries work fine, but it seems particularly if I don't use the server for perhaps more than 15 minutes, when I return I get hanging, but it seems only on a POST request on the pages served from tomcat. The hang usually last 1 minute before the 502 error. Also I have seen it on GET pages but not recently, so it may be that some of the configuration changes I made changed that.

I've enabled debugging in the log and get:

[Sat Jan 30 21:28:49 2016] [error] [client 192.168.213.24] (70007)The timeout specified has expired: proxy: error reading status line from remote server localhost, referer: http://analytics.mysite.com/analytics/msqlQuery
[Sat Jan 30 21:28:49 2016] [debug] mod_proxy_http.c(1414): [client 192.168.213.24] proxy: read timeout, referer: http://analytics.mysite.com/analytics/msqlQuery
[Sat Jan 30 21:28:49 2016] [debug] mod_proxy_http.c(1465): [client 192.168.213.24] proxy: NOT Closing connection to client although reading from backend server localhost failed., referer: http://analytics.mysite.com/analytics/msqlQuery
[Sat Jan 30 21:28:49 2016] [error] [client 192.168.213.24] proxy: Error reading from remote server returned by /analytics/msqlQuery, referer: http://analytics.mysite.com/analytics/msqlQuery
[Sat Jan 30 21:28:49 2016] [debug] proxy_util.c(2112): proxy: HTTP: has released connection for (localhost)

When I get the hanging behaviour, I don't see anything show up in the tomcat logs at all. I suspect that the call is never getting that far.

It's as if Apache thinks the connection is alive, but it's not somehow (even though I think I've configured it to get a fresh connection every time)

Many thanks for any assistance!

user1471465
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2 Answers2

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EDIT: Nope, this didn't fix it. Though to be fair, the problem this time was that when I came back to it several hours later, a GET request was hanging. When I refreshed the page 6 times, it started working. I do have basic authentication on there too, however. Really not sure what's going wrong.

PREVIOUS POST WHEN I THOUGHT I'D FIXED IT: Hmm, it looks like I may have fixed it. When it was hanging, even though there was nothing in the tomcat logs, I thought I'd try stopping tomcat and see if that caused a connection error next time I tried to load the page. It did cause an error, which made me think maybe the problem was in the tomcat config.

I changed this in web.xml:

<session-config>
    <session-timeout>30</session-timeout>
</session-config>

to

<session-config>
    <session-timeout>1</session-timeout>
</session-config>

Perhaps tomcat was holding onto the session?

I don't really understand it yet, and not 100% sure it's fixed but it seems to be. Will post back if this is not the right answer.

user1471465
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I'm glad you figured it out. When I started reading your question I was already thinking about the "session"

I have a couple of Java applications running with reverse proxy in apache and it took me awhile to get them working properly.

Nelson Amaya
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