Re: POSIX semaphores in JNI?

From: Stefan Poehn (stefan.poehn_at_IH8SPAMbms.de)
Date: 07/26/04 

Date: Mon, 26 Jul 2004 12:34:36 +0200

"Kevin McMurtrie" <mcmurtri@dslextreme.com> schrieb im Newsbeitrag
news:mcmurtri-6D6280.00275024072004@corp-radius.supernews.com...
> Can POSIX semaphores be used in Java 1.4.2 JNI code? I have a C++ image
> rendering library that is I/O, memory, and CPU intensive. The
> operations can be lengthy and various stages of rendering are cached.
>

I have used Win32 and vxWorks Semaphores in a JNI project (2 years ago) and
both worked fine. Are the vxWorks semaphores posix compliant?

If you call a method that blocks on a taken semaphore, it does not matter if
you call from C/C++ or Java, all methods will block.

The only pitfall I have encountered is: You cannot create a thread in C/C++
and send any calls to the java virtual machine before you call
AttachCurrentThread.

> The thread management is fairly complex and fined-grained to make sure
> that operations do not interfere with each other, especially during I/O.
> Is it OK to use POSIX recursive semaphores to control threading? The
> JNI docs don't mention it. Information on the web conflicts or is
> obsolete (mentions green threads problem).
>
> MacOS X uses 1:1 pthreads. For Linux and Solaris, I'm not sure if the
> POSIX routines are safe. JNI threading could replace POSIX threading
> but I'm worried about its performance with large caches and numbers of
> semaphores. Also, maintaining proper references to the Java sync
> objects will be non-trivial. This library has an eventual memory
> corruption problem on Solaris only. I don't know if I should spend two
> days rewriting my semaphore C++ class for JNI threading or keep looking
> for the usual C++ memory bugs. The crash takes 6 to 12 hours to appear
> so debugging is time consuming.
>
>
> Thanks

Relevant Pages

  • POSIX semaphores in JNI?
    ... Can POSIX semaphores be used in Java 1.4.2 JNI code? ... Is it OK to use POSIX recursive semaphores to control threading? ...
    (comp.lang.java.programmer)
  • Re: pragma importing sem_init gives me a segmentation fault
    ... POSIX semaphores by pragma importing sem_init, sem_post, sem_wait, ... previous semaphore calls were SGI specific and we were looking to move ... There is a package available for GNAT called florist. ...
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  • Re: CreateThread Fails with ERROR_NOT_ENOUGH_MEMORY....
    ... We were able to figure out the stack of the culprit func. ... We have dispatched the bug to the relevant group owning the routine which was leaking semaphores & events & they are looking into it now. ... As far as the VM usage is concerned, I still believe that, given the amount of stress involved in the test, we are bound to run out of virtual memory. ... Now about the memory leak. ...
    (microsoft.public.win32.programmer.kernel)
  • Complete list of process attributes?
    ... memory, shared segments ... memory, shared segments (SysV) ... memory, data segment, arguments ... semaphores, memory ...
    (comp.unix.programmer)
  • Re: process safe communication
    ... My first task is to port a queue ... > System V (named semaphores, ... > My goal is to use POSIX as I see that as the most high level and easy ...
    (comp.unix.programmer)