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Java Forum / General / December 2006Getting GC output in Tomcat
Hi all, I want to get Garbage collector ouput in Tomcat 5.x. Can someone explain how to get this going? I tried using "-verbose:gc" in CATALINA_OPTS. But it doesn't seem to work. Any ideas?? ... > I want to get Garbage collector ouput in Tomcat 5.x. Why? Do you suspect an application has a memory leak? Andrew T. Yes...I keep getting OutOfMemoryException...wud like to c how often the gc is running.. > ... > > I want to get Garbage collector ouput in Tomcat 5.x. [quoted text clipped - 3 lines] > > Andrew T. Please refrain from top-posting. I find it most confusing. > > ... > > > I want to get Garbage collector ouput in Tomcat 5.x. > > > > Why? Do you suspect an application has a > > memory leak? ... > Yes...I keep getting OutOfMemoryException... Note that calling GC will *not* *fix* a memory leak. I feel the time is better spent finding the source of the memory leak, than worrying about when Tomcat is calling the (largely pointless) GC. What sorts of things is the server doing (accessing D/B, image editing etc.)? How fast does the problem manifest? Does it take 101 days to hit 'max memory' and crash, or is it crashing every couple of hours? Andrew T. Hi Andrew, Yes. I do know that calling GC will not help. But I'm facing a weird problem..The same app is being run on two systems and the same requests are made on both the systems....the amt of data handled is also the same in both...for e.g., if I'm sending the same 100 requests to both the servers, all 100 go through in one but the other crashes in between complaining of outOfMemoryException...both the systems have the same memory settings...so I was wondering if there is some problem with the GC on the crashing system... thanks for your help.. .... > Yes. I do know that calling GC will not help. But I'm facing a weird > problem..The same app is being run on two systems and the same requests [quoted text clipped - 4 lines] > memory settings...so I was wondering if there is some problem with the > GC on the crashing system... That seems like a much better description from which to start, but it now tells me I am beyond my area of expertise. It might also be relevant/helpful to add the Java versions and Tomcat versions on both systems, and a little more detail of the 'requests' and their responses. E.G. what is the format of the data being passed around? (Strings/form data, images, 3D models..?) What is the processing that is done (D/B requests, image translation and resizing, delivering a model as data to an application?). Andrew T. > Hi Andrew, > Yes. I do know that calling GC will not help. But I'm facing a weird [quoted text clipped - 7 lines] > > thanks for your help.. Get a profiler and find out what kind of objects are occupying all that memory and where they are created. Eclipse and NetBeans have free profilers, or you could get a trial version of a commercial product (such as JProfiler, JProbe or YourKit). Dan.  SignatureDaniel Dyer http://www.uncommons.org Hello all, I've used the Eclipse profiler and confirmed that there is no memory leak...because it is running perfectly fine in one system....the app gets HTTP requests for data over a period of time....the data is in files which have a proprietary format(no database used)...and the data is returned as graphs/tables etc... Version of Java is 1.4.2.11 and tomcat version is 5.0.028 > Hello all, > I've used the Eclipse profiler and confirmed that there is no memory > leak...because it is running perfectly fine in one system.... Did you profile it while it was running on the system that it has been failing on? Profiling it on the other system wouldn't be helpful because you need to reproduce the problem while the profiler is attached. Finding out what is filling up the heap should help identify the cause of the problem. There is presumably some subtle difference between the two systems that is triggering this behaviour. It could be a bug in your application, or a bug in Tomcat. Dan. SignatureDaniel Dyer http://www.uncommons.org YourKit Java Profiler http://www.yourkit.com shows graph of GC activity: number of invocations, invocations per second (minor and major collections), number of invocations in last minute, etc. BR, Vladimir "Gugle" <gugle.rulez@gmail.com> said: >Hi all, >I want to get Garbage collector ouput in Tomcat 5.x. Can someone >explain how to get this going? >I tried using "-verbose:gc" in CATALINA_OPTS. But it doesn't seem to >work. Any ideas?? Depending on your JVM version, you can log the gc output to a separate file: "-Xloggc:filename" among the JVM startup options is your friend. SignatureWolf a.k.a. Juha Laiho Espoo, Finland (GC 3.0) GIT d- s+: a C++ ULSH++++$ P++@ L+++ E- W+$@ N++ !K w !O !M V PS(+) PE Y+ PGP(+) t- 5 !X R !tv b+ !DI D G e+ h---- r+++ y++++ "...cancel my subscription to the resurrection!" (Jim Morrison) Thanx Juha! > "Gugle" <gugle.rulez@gmail.com> said: > >Hi all, [quoted text clipped - 10 lines] > PS(+) PE Y+ PGP(+) t- 5 !X R !tv b+ !DI D G e+ h---- r+++ y++++ > "...cancel my subscription to the resurrection!" (Jim Morrison) Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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