-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Rob,
On 10/7/2010 7:07 PM, Rob G wrote: > Christopher Schultz wrote >> I think you might want to compare the request processor counts you >> have for Tomcat versus mod_jk: the default maxThreads for a Tomcat >> <Connector> is 200, while your MaxClients settings might be >> different on your Apache httpd configuration. > > Excuse my ignorance, but can you clarify where I check these settings? Obviously, the worker settings are in your Workers.properties file that you've already posted. The settings for Apache httpd are usually in a file called conf/httpd.conf in the Apache httpd installation directory. On win32, that might be something like C:\Program Files\Apache Foundation\Apache Web Server\conf\httpd.conf Tomcat's server settings are in conf/server.xml in the Apache Tomcat installation directory. On win32, that might be something like C:\Program Files\Apache Foundation\Apache Tomcat\conf\server.xml Since you have two copies of Tomcat working, you should check both of them. In fact, if you could post the server.xml files from both instances and tell us how you have them configured to run side-by-side, that would be helpful. Pid pointed out that you might not have both instances running due to a shutdownPort conflict. That might also be the case if you have other ports that conflict. >> I believe that only the Worker MPM is available on Microsoft Windows. Have >> you explicitly configured an MPM? > > Since I don't know what an MPM is I'm going to say no. :) That stands for "Multi-Processing Module" and it's how the Apache Web Server serves more than one request at a time. On *NIX, you can choose the "prefork" module which gives you one child process per simultaneous request, or the "worker" module which gets you a single (child?) process with many threads running within it. I just checked the documentation and it looks like on windows, you get mpm_winnt, which is different from even those, though it quite resembles the mpm_worker. >> Since you're using Apache 2.x, mod_jk should be able to >> auto-configure this value for you. > > Do I need to set anything to allow this auto config to happen? No. If you don't set any value, mod_jk will compute a reasonable (and usually correct) default. For a prefork MPM, having more than a single connection in the connection pool is a huge waste, since a single httpd request processor can't make more than one connection to Tomcat on the backend. With the worker MPM, the connection pool should probably be the same size as the number of worker threads you have configured. Otherwise, you'll have a deficit that may cause the errors you are encountering. >> From my reading, you may be limiting yourself to 10 simultaneous >> connections from Apache httpd to Tomcat, and others will get a >> 503. > > What lead you to that conclusion? Here's the text from the docs: " This directive has been deprecated since 1.2.16. Cachesize defines the number of connections made to the AJP backend that are maintained as a connection pool. It will limit the number of those connection that each web server child process can make. Cachesize property is used only for multi threaded web servers such as Apache 2.0 (worker), IIS and Netscape. The cachesize property should reflect the number of threads per child process. JK will discover the number of threads per child process on Apache 2 web server with worker-mpm and set its default value to match the ThreadsPerChild Apache directive. [...] " Since mpm_winnt (like mpm_worker) uses ThreadsPerChild to set the number of worker threads (and therefore simultaneous requests that can be accepted), you'll have to know what ThreadsPerChild is set to. That's easy: just search for that directive in httpd.conf. If it's not there, or commented-out, the default is 64 on mpm_winnt (http://httpd.apache.org/docs/2.0/mod/mpm_common.html#threadsperchild). If you've left it as the default (64) and you've set worker.cachesize (really worker.connection_pool_size) to 10, then you can accept 64 connections from clients but only call-out to Tomcat over 10 of those connections: the others will have to wait. I'm not sure what the scheduling algorithm is for choosing which thread gets the next available connection from the pool (FIFO?), but it's very possible to starve your clients even after 10 simultaneous connections. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkyvKLwACgkQ9CaO5/Lv0PBAqgCgh3/TNdasW5b6cnHXOP99BxrL jCIAmgMt/kFdRWIut1m9QF8TmzbZ7zW3 =LXSf -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
