[gambit-list] Problem in thread-sleep! may be a poor

Oisín Mac Fhearaí denpashogai at gmail.com
Tue Jan 27 22:33:14 EST 2009

2009/1/28 Marc Feeley <feeley at iro.umontreal.ca>:
> David St-Hilaire was experimenting with the following program:
> (pp n) ;; expected value of n is approximately 10000
> The value printed for n on his Linux computer is approximately 100.  When I
> try the program on my Mac OS X computer I get a value much closer to the
> expected 10000.
> After digging around it seems that the resolution of the "timeout" parameter
> to the "select" system call (which is used by the scheduler to wait for I/O
> and/or a timeout) can vary greatly from one OS to another.
> I'm curious to know how well other operating systems handle the timeout.
>  So, if you have access to some unusual operating system, could you try the
> above program and report back what value is printed?

Are you sure? I'm also on OS X (10.5 on a reasonably fast x86) and I
get almost exactly 100 every time for the program you pasted:

Lyrebird:sicp oisin$ gsi test-threads.scm
Lyrebird:sicp oisin$ gsi test-threads.scm
Lyrebird:sicp oisin$ gsi test-threads.scm
Lyrebird:sicp oisin$ gsi test-threads.scm
Lyrebird:sicp oisin$ gsi test-threads.scm

It behaves the same when compiled. So even in the same OS (unless
you're on a different version of OS X?), it seems these scheduler
settings can drastically alter thread performance characteristics.

> I also wrote the C program below to test the resolution of select's timeout.
>  You can try that too.

Lyrebird:sicp oisin$ time ./a.out

real	0m1.606s
user	0m0.026s
sys	0m0.088s


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