9fans archive / 2001 / 04 / 690 /    prev next

From: Scott Schwartz <schwartz@bio...>
Subject: [9fans] threads in Plan 9
Date: Fri, 27 Apr 2001 15:23:09 -0400

| For writing some applications, limbo is quite pleasant.  I've written
| concurrent ("multithreaded") programs in limbo and felt comfortable
| doing so, whereas using the Unix LWP (light-weight process) libraries
| (or POSIX threads) directly has always seemed hazardous.

On a slightly different topic, it has also seemed hazardous to me in
Plan 9.  One particular thing, for example, is that there's no way to
tell the system that a cohort of processes should be treated as such.
I used to have great fun with mothra when one process would crash, and
leave the rest deadlocked or otherwise boggled.  On those occasions,
I felt like a multi-threaded application should have a kernel-enforced
way to fail as a unit, as if there was a suicide_pact() system call,
or something like the "reboot" device, so that of one process dies
unexpectedly, the others do too.

| libthread attempts to capture some of the benefits of limbo (notably
| communication) in C, but I'd rather have one kind of process (not
| processes and threads) and it feels a little like LWP libraries to me,
| plus you don't get the concise limbo communication syntax and
| automatic memory (de)allocation.

Agreed.