Hi,
I just stumbled over the impression, that doing multi-process builds
(e.g. -P2), at least when hot, need significantly more time than
single-process builds.
E.g. building the Writer, in case nothing actually needs to be build,
gives something as:
[EMAIL PROTECTED] sw> time build.pl -P2
....
Multiprocessing build is finished
Maximal number of processes run: 2
2.884u 0.972s 0:36.42 10.5% 0+0k 0+0io 2pf+0w
[EMAIL PROTECTED] sw> time build.pl
...
2.956u 0.828s 0:04.02 93.7% 0+0k 0+0io 0pf+0w
That means, build.pl needs 36s if it has been called with -P2 and 4s if
called plain. Looking at the output while building gives the impression,
that there are some sleeps when waiting for forked processes to return.
Taking a look at build.pl I can find several "sleep 1" instructions.
Commenting out line number 1435:
# sleep 1 if (children_number() >= $QuantityToBuild);
gives:
sw> time build.pl -P2
...
Multiprocessing build is finished
Maximal number of processes run: 2
4.564u 1.088s 0:06.60 85.4% 0+0k 0+0io 0pf+0w
which is near to the single process case.
I think I understand the purpose of the "sleep 1", actually to wait for
forked processes to terminate, though I think that a "sleep" is not the
best solution and I would vote for something like a "waitpid" or similar.
Regards
Kay
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