Why does the OS X 64-bit kernel say it's out of memory?

Due to a problem Apple introduced in the Intel version of the OS X in a March 5th Software Update, the 64-bit kernel may crash, resulting in this error message.

No more memory available.
Mathematica kernel has shut down.
See http://support.wolfram.com/mathematica/systems/macintosh/osx/64bit.html
for information on 64-bit memory operation on Macintosh.

The error message is misleading since the problem is not a lack of memory. What has actually happened is that the 64-bit kernel has crashed due to this Apple operating system problem.

The problem will occur any time the 64-bit kernel attempts to open more than 16 files at one time. The files may be opened directly with the Open command, or indirectly through various other commands. In Mathematica 6, the data paclet manager tends to open multiple files and may therefore trigger this problem fairly commonly when using paclet features. (Note that this problem does not affect the front end. Mathematica has no problem having more than 16 Notebook windows open.)

Unfortunately there is nothing we can do to fix the problem, which is in the core Apple 64-bit operating system libraries. We are working to encourage Apple to release a patch for this bug, but at this time they have not provided us with a date when such a patch might ship.

Currently shipping versions of Mathematica have their 64-bit kernel disabled to avoid this problem. If you are using an older version of Mathematica with its 64-bit binary enabled on an Intel-based Mac OS X machine and are encountering problems, you may wish to temporarily disable the 64-bit kernel.

If, on the other hand, you are using Mathematica 6, you may wish to enable the 64-bit kernel (for example if you are running out of memory using the 32-bit kernel). This can be done safely provided you don't use any commands that trigger the OS X operating system problem. (If you do trigger the crash, it is only the kernel that crashes, not the front end. This should not cause any loss of work you have saved in your notebook files.)

Download this FAQ as a Mathematica 6.0 Notebook

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