-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Sylvain,
This thread is bit old, but there were no conclusions si I figured I'd pick it back up. On 4/11/14, 11:52 AM, Sylvain Goulmy wrote: > Thank you all for your returns. > > Maybe also, just to give us an idea, you could tell us how much > memory that >> system has, and how much is given to use by Tomcat ? > > > Xmx is 1500 Mo. The PermSize is set so that it can easily load the > max number of JSP set with the maxLoadedJsp (set to 5000) > parameter. Assuming this is 1500MiB, then 16000 JSPs might have trouble fitting in here. Can you see how much space java.lang.Class objects are taking? How about how many JSPs are actually loaded? Presumably, you have 16000 .jsp files on the disk, but maybe only 1/2 of them are actually loaded before you have any problems. >> 1. Personally I am pessimistic about 'maxLoadedJsps' option, >> because even if you unload a JSP, the strings used in its code >> will still remain in JVM constant strings pool. Anyway, I expect >> the best performance would be if you do not try unloading the >> JSPs. 2. Did you set development=false on JspServlet? If Class objects are unloaded, they will not pin any data in the JVM string constant pool. You don't have anything to fear, here. What you *do* have to worry about is the buffers that JSP ends up using for custom tags. I can't remember the exact mechanics, but whenever a tag is executed, the content generated within it must be buffered in case of an error -- so an error message can be generated instead of failing "silently" to the remote user due to a response-already-committed problem. Anyway, when those buffers are expanded, they never shrink again. So, over time, all your buffers will grow enormous if you have a few places where this kind of thing can happen. The number of JSPs does not matter: you can do this with a single unfortunately-written JSP or with 16k of them. But given the extensive use of JSPs on your site, this is a likely candidate for any problems you are encountering. Are you getting OOMEs? Have you enabled verbose GC to see if the slowdowns are associated with GC pauses? It seems like you are coming to us with the problem "things are slow" and asking us to figure it out for you. Sorry, but you are going to need to provide more information. >> http://tomcat.apache.org/tomcat-7.0-doc/jasper-howto.html#Production_Configuration >> >> Note: I would not recommend using 'genStringAsCharArray', >> 3. There are a number of ways to monitor your memory usage. 4. >> Does the number of requests remain the same and only the number >> of JSPs increases? How much is "longer" in "the response time >> becomes longer" ? > > > 1. This is indeed a scenario i want to test, ie to size the PermGen > so it can load all the JSP without having to unload them. This > could require a huge PermGen size that i have to assess. java.lang.Class objects don't take a huge amount of memory. You will likely have to increase PermGen from the default, but you won't need a gigabyte or anything like that. > 2. development=false and i don't use the "genStringAsCharArray" > parameter > > 3. I'm using many tools which allows me to monitor the GC > behaviour What do those tools tell you? > 4. Here is the behaviour that i observed : i request the URL of a > jsp in a loop. The content of this JSP is always the same but it's > name is different in each URL so that it is considered as a new > one. This JSP is quite big (100 ko). Here is the evolution of the > response time : > > - First call : 70 ms - 1000th call : 100ms - 2000th call : 140 ms - > 3000th call : 200 ms The size of the .jsp file is not relevant. What is relevant is the "complexity". IF you just have 100kib of text, then there is no work/buffering to be done, for instance. > The more the permgen hosts many JSP, the more the response time > increases. On this test, the PermGen was big enough to host all the > JSP and the maxLoadedJsp parameter is set to 5000. What happens if you remove the maxLoadedJsp setting? Do you get an OOME? >> Is this performance problem something you didn't have before >> today? > > No indeed, we were on a different technology (Websphere). Same technology (JSP), different implementation. So, you can't give anyone some samples, eh? But you said you were able to replicate this with some simpler example? Did you use an example from your own web application or did you just create a sample .jsp and copy it to different names over and over again? If you help us reproduce the problem, we may be able to find a solution. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCAAGBQJTVSMsAAoJEBzwKT+lPKRYMS8P/2qOP8A74qPtRQL/1wXcw39p uJ1i9f3ml+vP2PB1Ujcxv2zeZIL8ztL/ClpJwk5nWh2mZW+S9ZUE15eozddzMn4d qbKT9brtTZWstX0HROY11yaMG52lQwsktw5TPwsLeRtSyvUSG2qTEohXYe8sRf/s ZMfYNdpgTED7RW+6iIooIN2YZMFSLUF6dyx0Up8sPRLFacDlGQw+v0BiLxyTSAev Fn1nsccGJ5wbSqVOZR8m8AtgCMzouAgxE7Ct0B/TI7d4ek7M1k9ba9mjk5xEvN/Y 4W/gJxr6f3NA0Mqw1zjhsIWjSUUf4o4q5ZhtoeihWWcBFaltO7dLymCFSxiXe/l3 rM73PfFZTKSo8SIGi0sXPfCFqH+2hUMaABLLGhRI0UzFU65nO3mKYbLFaNNc+sej djNROjcmKt+MZs2JpUGttePjefeqhIlHWzgsvowb4QOob/ACm/r0xKN+byDR0NzP DQwLfxglnbxO95TwiuhEBVAKuMI4fVwNX0xNnoCQlh6K92R+nP9NZ4/PLWjkDKk/ bB6HUJWJMw36i08xq1u+O/6bOYAeJZtt7fZFBlSz9ASGtpXDZOXhiao0JUOmrj9y Pd3zUFz1uY0+pymp3aamXTwSEI49OY3LfM1TIT09h2bqsZtIA+UYiMSLMTgY591/ pwg8Ts0K4enWoVhq0P+5 =1DhS -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
