Why is this Perl require line taking so much time?

Question

I have a Perl script that runs via a system() command from C. On a specific site (SunOS 5.10), when that script is run, it nearly always takes 6 seconds or more. On other sites, it runs pretty much instantly (0.1s). If I run the script manually, i.e. not from the C code, it also runs instantly. I eventually tracked the slowness down (by spitting out the time a whole bunch in a lot of different places), to a single require line. The file that it is requiring is another Perl script we wrote. The script consists of a single require (this file here), 3 scalars that are assigned integer values, and a handful of time/date conversion routines. The file ends with a 1;. That single require appears to take as much as 6 seconds on occasion, but as I said, not always even on the same machine. I'm absolutely stumped here. My only last thought is to turn on profiling, but the site doesn't have Devel::Profiler and my only other option (that I know of) would be to add it to the Perl command which would require me altering and recompiling the C code (doable but non-trivial).

Anybody have ANY idea what could be going on here? I don't think I can/want to put the entire date.pl that is being required, but it's pretty much exactly as I described; I could answer any questions about it that you have.

Thanks in advance.

Answer 1

Six seconds is a long time. Have you checked what your network is doing during this? My first thought was that spawning the new process when using the system() command could be the problem, but six seconds is too long. I don't know much about perl, but I could imagine that for any reason, the access of the time module could invoke a call to a network time server. Just to get synchronized. Maybe this takes so long or maybe it is getting a time out. It could be that this only happens for a newly spawned process -- hence only when you use the system() command.

just wild guessing...

Answer 2

You might be interested in A Timely Start by Jean-Louis Leroy. He had a similar problem and tracked it down to a long and deep module search path where perl usually found the modules in the last entries in @INC.

Answer 3

So, this does nothing to answer your question directly, but please tell me that you're not actually running on perl 4? Assuming you're on perl 5, you could remove the entire file and replace the require with use POSIX qw(ctime) to get the version that comes with Perl.

If you do have to support perl4, I'll merely grumble something about version 5 being fifteen years old now and go away. :)