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Java Forum / General / August 2006JBoss has jar limit ?
Hi I've encountered a serious problem in JBoss (because of the compatibility issues we are still using JBoss 3.2.1). After the number of jar files reaches a certain number (in this case 84) adding another jar crashes the server. Some services (like Log4jService) just fail during loading (I get a ClassNotFoundException). It's not about the size of the libraries (I've tried removing a big jar and adding two small ones) but about the number. I've tried many options for allocating more memory for application, libraries, heap etc. but it didn't work. I've also tried to to repeat the situation I described on another machine. It took more libraries, but did also occur. Has anybody an advice ? Regards > Has anybody an advice ? I have limited experience with JBoss, but in general you can repackage several jars into one as a stop-gap measure: To extract jar1.jar, jar2.jar and jar3.jar: jar -xvf jar1.jar jar -xvf jar2.jar jar -xvf jar3.jar then to create a new jar run: jar -cvf newjar.jar ./com ./org (whatever directories were extracted from the other jars). http://en.wikipedia.org/wiki/JAR_%28file_format%29 Watch out for signed jars. I wouldn't recommend this unless you have no other option and need to make progress. An upgrade might be in order. >> Has anybody an advice ? > [quoted text clipped - 9 lines] > jar -cvf newjar.jar ./com ./org (whatever directories were extracted > from the other jars). I thought of that, but it's rather a solution, not an explanation :-). Maybe anyone has an explanation ? Regards > I thought of that, but it's rather a solution, not an explanation :-). > Maybe anyone has an explanation ? Might be the number of open file descriptors. Is it running on UNIX? >> I thought of that, but it's rather a solution, not an explanation :-). >> Maybe anyone has an explanation ? > > Might be the number of open file descriptors. Is it running on UNIX? Even if it was running on UNIX I don't see how there could be enough files in the JARs(if all the files in each JAR was being opened all at once), let alone just the JARs themselves that would cause the OS to run out of file descriptors. The various UNIX flavors should have a minimum of around 32768 file descriptors, if not more. That may not be the exact number but I just know that it shouldn't be a couple hundred file descriptors like your question alludes to. I've seen Windows XP have over 700,000 file handles open and it didn't even phase it. > The various UNIX flavors should have a minimum > of around 32768 file descriptors, if not more. That may not be the exact > number but I just know that it shouldn't be a couple hundred file > descriptors like your question alludes to. I've seen this limit at 256 (per process) on different systems, but not lately. It can be ulimit-ed for the user. > > The various UNIX flavors should have a minimum > > of around 32768 file descriptors, if not more. That may not be the exact [quoted text clipped - 3 lines] > I've seen this limit at 256 (per process) on different systems, but not > lately. It can be ulimit-ed for the user. File descriptors include sockets, open libraries etc, maybe some other touch points into kernel resources. In my Solaris experience, and I think 4096 was the default hard limit on Solaris, but as you say, the soft limit can be lower. If 256 were the maximum, it could be very easy to exceed the limit. A search of the jboss site for file descriptors or MAX_FD turns up several results. > Even if it was running on UNIX I don't see how there could be enough > files in the JARs(if all the files in each JAR was being opened all at > once), let alone just the JARs themselves that would cause the OS to run > out of file descriptors. You don't need a file descriptor for each file in a jar file; one for each jar. > The various UNIX flavors should have a minimum > of around 32768 file descriptors, if not more. Typically the per process file descriptor limit is not set to be the system maximum. > That may not be the exact > number but I just know that it shouldn't be a couple hundred file > descriptors like your question alludes to. I've seen Windows XP have > over 700,000 file handles open and it didn't even phase it. Windows files objects are not the same as UNIX file descriptors except that they both point to filenames. Thanks for the insightful feedback. 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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