Re^2: How to set pipe first and then use the forkmanager?

[mlin]

Because establish the pipe to the program may be a little bit time-consuming. So I would like to move the open pipe outside the foreach() in the serial type. Similarly I consider may be I should establish pipe first and then use fork.

[Laurent_R]

Presumably, you're forking because your input data files are very large. The time taken to open a pipe is then negligible compared to the time needed for processing your data.

Don't forget that premature optimization is the source of almost all evil.

[mlin]

Thanks! I'll use this form at the moment, maybe I solve the problem when I know more about the fork. I have a new question: ----- complement: while the program A runs, it usually prints some information or warnings to the screen? Will it be a trouble for the forked processes? or I must throw the output of A, like:

foreach (@data_files) {
   open $h, "| program_A 2>& /dev/null" or die ...;
   print $h ...;
   print $h ...;
    ...
}
close($h);

Can I hold those information? Thanks!

[Laurent_R]

Hmm, not entirely sure, but I don't think that the forked process will care about that.

On the other hand, you might want to redirect to a log file (not /dev/null), if only to help getting a diagnostic if your process has errors and fails.