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libdispatch-dev@lists.macosforge.org

January 2010

6 participants
2 discussions

libdispatch's thread model
by Mario Schwalbe 29 Jan '10

29 Jan '10

Hi, when dispatching a bunch of jobs (blocks) to a global concurrent queue, libdispatch, running on Linux or FreeBSD, always spawns a thread for each job submitted. On Mac OS X it works as expected. This somewhat interferes with libdispatch's initial intention of a set of worker threads - equal to the number of processors - that execute each job in turn. Is there some chance to get that fixed? I know that Apple's non-posix extension to pthread isn't available. Nevertheless, it should be possible to at least use a bounded number of worker threads less than MAX_THREAD_COUNT (255). What about dynamically setting MAX_THREAD_COUNT (or a similar variable) to the number of processors instead? ciao, Mario

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Using darwinbuild to build libdispatch
by William Siegrist 25 Jan '10

25 Jan '10

I have added a plist to the repo that can be fed to darwinbuild to help build (and create patches for) libdispatch. Darwinbuild will automatically fetch roots from Mac OS Forge to populate your build environment with headers and libraries. You can find information about darwinbuild, including installation instructions, at: http://darwinbuild.macosforge.org/ Once darwinbuild is installed, do the following as root: $ mkdir ~/libdispatch-darwinbuild && cd ~/libdispatch-darwinbuild $ darwinbuild -init http://svn.macosforge.org/repository/libdispatch/trunk/libdispatch.plist $ darwinbuild libdispatch ... That will build libdispatch (/trunk HEAD). You can modify the subversion working copy of the source at: BuildRoot/SourceCache/libdispatch/libdispatch-1/ ... and then rebuild it: $ darwinbuild libdispatch ... and when you're done modifying it, you can generate a root to send to others: $ /usr/local/share/darwinbuild/packageRoots $ ls Packages/ libdispatch.root.tar.gz ... or generate a patch: $ svn diff BuildRoot/SourceCache/libdispatch/libdispatch-1/ > myfeature.patch ... or commit the changes from the working copy: $ svn ci BuildRoot/SourceCache/libdispatch/libdispatch-1/ -m 'Done' Darwinbuild stores the BuildRoot directory on a disk image, so if you reboot and find BuildRoot is a broken symlink, just invoke darwinbuild again and it will remount it. Each run of darwinbuild should update the working copy so you will always be building HEAD. You will need to watch for merge conflicts of course if you make changes to the working copy. Darwinbuild will leave a symlink in your /Developer/Platforms directory. Currently, you have to manually remove that symlink if you destroy your BuildRoot. If you have any trouble using darwinbuild for libdispatch, you can email this list, or for more general darwinbuild questions, email <darwinbuild-dev(a)lists.macosforge.org>. Thanks -Bill

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