While I haven't found anything quite like these for Darwin, sc_usage comes close. It provides a running statistical breakdown of system calls for any process ID (pid) specified on the command line. Although I haven't yet figured out how to parse its output, I expect it'll aid in figuring out where a particular app is getting hung up. In conjunction with fs_usage (mentioned in a previous hint by Ben Hines), you can also track down what files are being called. Note that this must be run in a Terminal window as root (generally via 'sudo').
Usage is:
sudo sc_usage [pid]Apple has a developer note describing the tool, with some examples, and you can always type man sc_usage in Terminal for typically laconic Unix documentation.
(Thanks go to Fred S., Apple's Open Source Engineering Lead, who posted about these utilities in a MacPerl thread.)
[Sudo Editor's caution: f you're not comfortable with the terminal and root privileges, I would recommend holding off on this hint. ]

