odd problem(s) with libthr and libkse

[Daniel Eischen]

On Sat, 11 Oct 2003, Christopher M. Sedore wrote:

> I have a multithreaded program that I've built to run under libc_r, libthr,
> and libkse.  I use the libc_r build for debugging and the others for actual
> work (the program is disk/network io intensive and I want the disk io
> concurrency from thr or kse).
>  Anyway, here is the issue I'm seeing.  It may be the same or a related
> problem for both, or may not be.
>  When running under libthr, everything works fine for an indeterminate
> period, usually between 10 seconds and 30 minutes.  Eventually, all program
> function stops.  If I watch in top, threads get stuck in "sigwai".  First
> one, then a couple, then all.
>  When running under kse, the program pauses periodically.  I have one thread
> that prints out a heartbeat once per second, and prints debug info.  I get
> pauses of up to 5 seconds between my heartbeat:

sigwait() may not be behaving as you'd expect in libkse.
It is slightly different than in libc_r, but should be
POSIX compliant nonetheless.

I use the following to test libkse for I/O intensive applications:

  http://people.freebsd.org/~deischen/kse/crew.c
  http://people.freebsd.org/~deischen/kse/sched_bug.c

The latter test may be similar to what you are describing.
It spawns a bunch of threads to perform disk I/O and one thread
that just sleeps and prints an incrementing number once a
second.

Use the first test as "crew node /usr/src" and it will spawn
worker threads to search for the string "node" in all files
in /usr/src.  It is one of Butenhof's tests.

Other than that, you'll need to give more info.  SCHED_4BSD
or SCHED_ULE?  SMP or UP?  scope system threads or scope
process threads?  Sample program to demonstrate the problem?

-- 
Dan Eischen