I work on a very large web application written primarily in perl. We're currently looking at ways to improve performance for larger numbers of users. It's plain old cgi, not mod_perl. We know that moving to mod_perl would help a lot, but it's a huge job and we want to get an idea of how much it will really help.

I'd like to know how much time is spent parsing and compiling each of our scripts each time they're run. I had the idea that the first line of my program could call 'time' and subtract $^T from it. Does $^T get set early enough that this would give me reasonable data? From this test script, it seems like it might: 

BEGIN
{
    print "BEGIN: $^T\n";
}
oh no!

[download]
The time is outputted before the compilation error.

I also thought about using the apache logs. I think I remember seeing a while ago that there's a way to record the total script time from there. I haven't looked into that yet. That would also hopefully include the overhead of apache starting a new process, so it might be more useful.

Any other ideas on measuring the startup overhead of running cgi scripts? Thanks.

In reply to measuring startup time: how early does $^T (start time of program) get set? by blahblahblah

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