> If you want to try it yourself and report back, I'm sure we'd all be > interested in what you find out. The main thing I'm aware of is that > copy-on-write works very well for preforking and threads usually can't > match it, but maybe your application is different. > > Regarding your thread-safety questions, chdir() is global to the process, > so not thread-safe. I think the issue with readdir() is that open directory > handles don't get copied when threads are spawned, but maybe there's more > to it. The special Perl vars are not a problem with threads, since each > thread is a separate interpreter. > > You can read about the limitations of threads here: > http://perldoc.perl.org/threads.html#BUGS-AND-LIMITATIONS
File handles, directory handles, cwd, uid, euid, gid, egid, signal mask (%SIG): anything defined in the process struct is shared among all threads. For example, the BSD proc sturuct looks like: <http://people.freebsd.org/~meganm/data/tutorials/ddwg/ddwg63.html> which gives a rough idea of what is in common. The only thing you can do with threads that forks make difficult is having multiple streams of execution working on a common data structure in parallel with about-to-block threads returning control before they actually do block. Nice for a web server or database, but you probably aren't writing an RDBMS in Perl :-) By the time your computing problem has percolated up to the level of Perl (vs. C) you are probably better off dealing with the work using forks (at least on *NIX) in order to avoid all of the locking, memory, and pool-manglement issues. -- Steven Lembark 3646 Flora Pl Workhorse Computing St Louis, MO 63110 lemb...@wrkhors.com +1 888 359 3508
