Re: make-3.82 testcases fail *sometimes*

[Paul Smith]

On Mon, 2010-08-30 at 19:52 +0200, Matthias Hopf wrote:
> All except those in targets/SECONDARY (which I do not 100% understand
> yet) are related to tests using sleep for parallelization tests -
> something highly unreliable on systems with lots of processors and
> high load.

Lots of processors shouldn't make a difference; if you "sleep 2" it'll
wait for (at least) 2 seconds, no matter whether you have one or 4,096
processors.

If your system is under very heavy load then I guess it could matter
although having a "sleep 2" take 4 or more seconds before you wake up,
for a simple command-line tool like make, seems like you would have to
have a REALLY REALLY high load.

Using configurable factors is not something I want to get into.  If it's
really the case that if you have two invocations of "sleep", one "sleep
2" and one "sleep 4", running at the same time, and you can't guarantee
that the "sleep 2" will finish before the "sleep 4", then we'll need to
find a completely different method of testing parallel builds.

Maybe we could do something like use locking files (one process sleeps
for a second and creates file X, another process waits for file X to
exist then sleeps for a second and continues).  The problem here is
doing it in a portable way, so it works on both UNIX and Windows (for
example) systems is not so simple.

-- 
-------------------------------------------------------------------------------
 Paul D. Smith <address@hidden>          Find some GNU make tips at:
 http://www.gnu.org                      http://make.mad-scientist.net
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist