tinny's questions

Apache2 reverse proxy seems to intermittently freeze when proxying a tomcat web app.

The problem is that every so often (once or twice a day usually after inactivity) when I try to log into this proxied web application it just freezes. The application just freezes indefinitely, no 500 response code... the browser just waits and waits.

If I keep trying to hint the web address from my browser it will eventually just start working again.

Ive tried to reproduce this issue by navigating directly to the web app on tomcat port 8080, but ive never been able to reproduce this without going through the reverse proxy.

Here is my reverse proxy config... any fault finding ideas? thanks

/etc/apache2/sites-available/default

ProxyPass /manage/ http://localhost:8080/manage/
ProxyPassReverse /manage/ http://localhost:8080/manage/

ProxyPass /manage http://localhost:8080/manage
ProxyPassReverse /manage http://localhost:8080/manage

/etc/apache2/mods-available/proxy.conf

  <IfModule mod_proxy.c>
    #turning ProxyRequests on and allowing proxying from all may allow
        #spammers to use your proxy to send email.

        ProxyRequests Off

        <Proxy *>
                AddDefaultCharset off
                Order deny,allow
                Deny from all
                Allow from all
        </Proxy>

        # Enable/disable the handling of HTTP/1.1 "Via:" headers.
        # ("Full" adds the server version; "Block" removes all outgoing Via: headers)
        # Set to one of: Off | On | Full | Block

        ProxyVia On
    </IfModule>

More info: (not sure if relevant)

• Each web page is averaging 2 - 3 Ajax calls
• Haven't applied 14 Rules for Faster-Loading Web Sites. Looking to apply expires header for caching static content soon.

Enabled apache modules:

core_module (static) log_config_module (static) logio_module (static) mpm_worker_module (static) http_module (static) so_module (static) alias_module (shared) auth_basic_module (shared) authn_file_module (shared) authz_default_module (shared) authz_groupfile_module (shared) authz_host_module (shared) authz_user_module (shared) autoindex_module (shared) cgid_module (shared) deflate_module (shared) dir_module (shared) env_module (shared) mime_module (shared) negotiation_module (shared) proxy_module (shared) proxy_ajp_module (shared) proxy_connect_module (shared) proxy_http_module (shared) reqtimeout_module (shared) rewrite_module (shared) setenvif_module (shared) status_module (shared)

Update: I am now using the ajp protocol for the proxy. An have set some addition ProxyPass config e.g.

ProxyPass /manage ajp://localhost:8009/manage max=20 ttl=120 acquire=10000 retry=0
ProxyPassReverse /manage ajp://localhost:8009/manage

I have a Grails web application (just a standard war file) deployed on a Ubuntu 10.10 server running on tomcat 6. My database is postgresql.

The problem is that every so often (once or twice a day after inactivity) when I try to log into this web application it just freezes. I can navigate to the login page but when I try and login (first time the DB is hit, might be a clue..?) the application just freezes indefinitely, no 500 response code... the browser just waits and waits.

I followed the instructions detailed here

because the problem described sounded the same as mine. My GC logging showed no long running GC, all sub sec.

When the application freezes a jmap heap output is...

using parallel threads in the new generation.
using thread-local object allocation.
Concurrent Mark-Sweep GC

Heap Configuration:
   MinHeapFreeRatio = 40
   MaxHeapFreeRatio = 70
   MaxHeapSize      = 536870912 (512.0MB)
   NewSize          = 21757952 (20.75MB)
   MaxNewSize       = 87228416 (83.1875MB)
   OldSize          = 65404928 (62.375MB)
   NewRatio         = 7
   SurvivorRatio    = 8
   PermSize         = 21757952 (20.75MB)
   MaxPermSize      = 85983232 (82.0MB)

Heap Usage:
New Generation (Eden + 1 Survivor Space):
   capacity = 19595264 (18.6875MB)
   used     = 11411976 (10.883308410644531MB)
   free     = 8183288 (7.804191589355469MB)
   58.23843965562291% used
Eden Space:
   capacity = 17432576 (16.625MB)
   used     = 9249296 (8.820816040039062MB)
   free     = 8183280 (7.8041839599609375MB)
   53.05754009046053% used
From Space:
   capacity = 2162688 (2.0625MB)
   used     = 2162680 (2.0624923706054688MB)
   free     = 8 (7.62939453125E-6MB)
   99.99963008996212% used
To Space:
   capacity = 2162688 (2.0625MB)
   used     = 0 (0.0MB)
   free     = 2162688 (2.0625MB)
   0.0% used
concurrent mark-sweep generation:
   capacity = 101556224 (96.8515625MB)
   used     = 83906080 (80.01907348632812MB)
   free     = 17650144 (16.832489013671875MB)
   82.62032270912317% used
Perm Generation:
   capacity = 85983232 (82.0MB)
   used     = 62866832 (59.95448303222656MB)
   free     = 23116400 (22.045516967773438MB)
   73.1152232100324% used

Anyone know what "From Space:" is?

Any ideas on further fault finding ideas? I dont have much experience with this type of fault finding.

Im currently using ufw to enforce some basic firewall rules. Is it possible to also use ufw to do port forwarding?

Specifically im wanting to forward incoming traffic to my server (same machine running ufw) on port 80 to port 8080. (http traffic forwarded to tomcat)

Th