-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 André,
On 3/20/13 2:25 PM, André Warnier wrote: > Saurabh Agrawal wrote: >> All our assets are served from L3 CDN. So the asset requests >> never come to the application server. > > That, I do not understand. I do not understand what you mean by > "assets" here, and I do not understand "L3 CDN". So I cannot tell > of this is relevant or not to the problem. CDN = Content Delivery Network. I'm not sure what "L3" (probably "Level 3", a data center operations company) is, but a CDN is basically a whole bunch of copies of your files geographically distributed such that requesting a file always gets the bits that are closest to you. Kind of a cool thing. ;) The bottom line is that Saurabh expects only dynamic requests to come to Tomcat, so keepalives should be much less useful than if Tomcat were to be serving everything. Imagine httpd out front serving all static content and forwarding dynamic stuff to Tomcat via AJP -- that's almost exactly what's going on here, except that the static stuff is being served very efficiently from a network-topology perspective. Since AJP is in use, keepalive is almost entirely a red herring as typical AJP connections are permanently-connected to the web server. > So, by default, the keepAliveTimeout [for AJP] is set to > "infinite". > > [snip] > > And if the client keeps the connection open, but does not send any > additional request on that connection, the Thread will wait > theoretically forever (because that is what the documentation says > about the default value of these parameters). No, the defaults are different for non-AJP connections. Tomcat's default default is 60 seconds but the stock server.xml configures it to 20 seconds. > Now your case is a bit different, because - you are not using the > HTTP BIO connector (you use AJP) I think you've gotten yourself confused, here, unfortunately. You can use AJP with BIO, NIO, or APR (maybe you mixed-up AJP and APR between your eyes and your brain... the two are honestly too close to each other and it is very easy to do that). He is in fact using the BIO connector because he has specified protocol="org.apache.coyote.ajp.AjpProtocol". > - in front of your Tomcat, is an Apache httpd server. This server > has its own keep-alive settings which apply to the connection of > the client with Apache httpd. And these keep-alive settings are a > bit different from the Tomcat ones (for example, there is a > keep-alive timeout, but also a MaxKeepAliveRequests) +1 > - between Apache httpd and Tomcat, there is the mod_jk module in > Apache, and that module uses its own timeouts (as set in > workers.properties), and in addition it uses itself a pool of > connections to Tomcat, and this pool of connections has its own > rules for keeping alive a connection between Apache and Tomcat. > > But the basic principles above apply, and may explain why you are > seeing what appears to be one Thread dedicated to one client, > forever. I think there might be a problem with the instrumentation, or just coincidences at a fairly implausible level. The trust of the matter is that Tomcat does not allocate a thread permanently to a remote client until ... whenever the client "disconnects" (whatever that means, as HTTP is a connection-less protocol). - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCAAGBQJRSlo8AAoJEBzwKT+lPKRYodAP/Rz73chvzhyYPNWpePlvPaBm x7bFxFCNg7hbHV7X1skgfG4CYbR9AsjFqcgkXovVSBcIZjKoNT/yCqwL20SMdNIo glkx1Gz6gBfM8Ad68VL4xr7nGtwC1WraN2tCszc8dNrBJOjmQwp5tX09OWtpsxqe DNQVfhGk8wtHmPWjXgK8Kr0lZDjfz540bp4OSAwohjixsCTr3C1PqVEiiZyYWazC B/5tEkeJ7YtPQJqmJhgx1uR+CmU3ty5iQpLmr4K9uKTLSTjs3HGFV0nkCKQIXmQs vzjt0eWr8VzbbZnY4QBfBIntgjQiDIoK9Mi+Q3uilYbjCJuFw4jJGICAjaZjlYxW eW29Ag/WGthB6shOwStiLS+/KUenzXY9aNzHQ1sCeB9Pdsy2eI+Yg15TomwcfxcV 2LjtHZO13QQeGcHpr5vBId8x/B9x5W1bzs8gzUALPQhdsYqGixohu4Ad4nqmeBI0 VZ02jiEDQqr4zT6oJwDVPpm8FSS2wBZKURIp80iI4B2+bS1VPcKzY/J/aKCQRQCw KP4VDtNiAOXD4a+8sHuZrOh8Q/splNnbhf2G687PryjfxQuk+HQPY/XfFvY1CXzD ZZD1yVjkSaRfXDmDCfFxfD+a3lOmGhAa8NNR4dtJJo1w1lhrYXvx1ujdS5V3FgO5 xdKlzkg4u30lRrAQq6IO =yLs6 -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
