AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  JNI CallStaticVoidMethod fails after N calls          AppletTalk.com Forum Index -> JVM, native methods and hardware View previous topic :: View next topic   Author Message Guest Posted: Tue Nov 21, 2006 7:47 pm    Post subject: JNI CallStaticVoidMethod fails after N calls I have written an application in Java and C on the Solaris 10 (x86) platform using the JDK 1.5.0_09. The Java code calls a native method "startButtonWatcher," which then forks, the parent process returning, and the child process initiating an event loop that calls a static method, "sendButtonEvent," on a Java class "ButtonWatcher." The problem is that on the 65 invocation, the CallStaticVoidMethod will hang. There is no core file or pid log file produced. (it will also hang for CallVoidMethod as well if I remove the static declaration in ButtonWatcher.) I have also added a main() function to the C code so that it can be compiled and run as an executable rather than a library file loaded from Java, and the the same loop will be fine, the Call*Method call being exected forever (or over a million times at least). The only difference in the code is the JVM--in the sharable library, it uses the JVM of the class that calls the native method, and the standalone has to create its own. What could be the problem? Thanks! Back to top Chris Uppal Guest Posted: Wed Nov 22, 2006 8:59 pm    Post subject: Re: JNI CallStaticVoidMethod fails after N calls santiago538 (AT) yahoo (DOT) com wrote: Quote: I have written an application in Java and C on the Solaris 10 (x86) platform using the JDK 1.5.0_09. The Java code calls a native method "startButtonWatcher," which then forks, the parent process returning, and the child process initiating an event loop that calls a static method, "sendButtonEvent," on a Java class "ButtonWatcher." You mean you actually call fork() to create a new Unix process ?? If so then I'm extremely surprised that it works at all, let alone 64 times before failing. If not then I presume you mean that you start a new OS thread from your C code (within the same Unix process). In that case I'd suspect that you are doing something "wrong" with your threads (or, also a plausible hypothesis unfortunately, that Sun are doing something wrong with /their/ threads), and that the difference in behaviour has little to do with the way the JVM is launched. Check that you are being completely clean about how you access AWT/Swing objects, and that you don't do /anything/ to them except from code runnng on the EDT. Of course, that's only a guess; another possibility is that you have a good old-fashioned deadlock which is not related to AWT at all... -- chris Back to top Guest Posted: Thu Nov 23, 2006 12:37 am    Post subject: Re: JNI CallStaticVoidMethod fails after N calls Chris Uppal wrote: Quote: santiago538 (AT) yahoo (DOT) com wrote: I have written an application in Java and C on the Solaris 10 (x86) platform using the JDK 1.5.0_09. The Java code calls a native method "startButtonWatcher," which then forks, the parent process returning, and the child process initiating an event loop that calls a static method, "sendButtonEvent," on a Java class "ButtonWatcher." You mean you actually call fork() to create a new Unix process ?? If so then I'm extremely surprised that it works at all, let alone 64 times before failing. If not then I presume you mean that you start a new OS thread from your C code (within the same Unix process). In that case I'd suspect that you are doing something "wrong" with your threads (or, also a plausible hypothesis unfortunately, that Sun are doing something wrong with /their/ threads), and that the difference in behaviour has little to do with the way the JVM is launched. Check that you are being completely clean about how you access AWT/Swing objects, and that you don't do /anything/ to them except from code runnng on the EDT. Of course, that's only a guess; another possibility is that you have a good old-fashioned deadlock which is not related to AWT at all... -- chris Hi Chris, I'm new to Unix programming, and I did use a fork(). I changed my code to use pthreads instead and it works fine now. Thanks Back to top Chris Uppal Guest Posted: Thu Nov 23, 2006 5:41 pm    Post subject: Re: JNI CallStaticVoidMethod fails after N calls santiago538 (AT) yahoo (DOT) com wrote: Quote: I'm new to Unix programming, No shame in that! ;-) Quote: and I did use a fork(). I changed my code to use pthreads instead and it works fine now. I'm glad it's working properly now. But I'm /really/ puzzled as to how the earlier versions could have worked at all. There must be something Very Strange Indeed about how Solaris handles dynamic link libraries. Oh well... -- chris Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> JVM, native methods and hardware All times are GMT Page 1 of 1   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.