Threading woes on FreeBSD

[Simon Marlow]

Gregory Wright wrote:
> 
> Some additional information on the threading problems
> experienced on FreeBSD.  The system was FreeBSD 6.1-RELEASE-p2,
> dual 2.8 GHz Xeon.
> 
> I built ghc-6.4.2 from cvs using the FreeBSD ports version of ghc-6.4.2.
> (The latter has the threaded RTS disabled.)  I ran the ghc-regress tests
> on the built compiler.  I used the libmap.conf (5) method to change the
> threading library from pthreads to libthr and libc_r.  The build from
> cvs uses pthreads by default.
> 
> The compiler using pthreads had 47 unexpected failures, and accumulated
> about 30 "timeout" processes, which were just burning cpu cycles.
> Using the reentrant c library (libc_r) gave essentially the same result,
> with a tens of "timeout" processes consuming cpu but apparently
> doing nothing else.
> 
> When I used the 1:1 threading library (libthr) the testing process  
> ground to
> a halt, with just one "timeout" process consuming about 95 percent
> of the cpu.  I kill the test, since it had not made significant  
> progress in about 5 hours.

That's a useful data point, we know that just switching to -lthr or -lc_r will 
not fix this.

> I'm going to set aside working on the FreeBSD threading question and
> concentrate on threaded runtime problem on OS X.  I had originally
> hoped that they would show similar behavior, but that seems to not be
> the case.

No problem, I'm on the trail of the FreeBSD problem (on your box :-).

Cheers,
	Simon