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From: worley@compass.com (Dale Worley)
Newsgroups: comp.lang.perl
Subject: caller doesn't work in signal handler
Message-ID: <1991Apr10.233240.29339@uvaarpa.Virginia.EDU>
Date: 10 Apr 91 23:32:40 GMT
Sender: mmdf@uvaarpa.Virginia.EDU (Uvaarpa Mail System)
Reply-To: worley@compass.com
Organization: The Internet
Lines: 52

I was hoping to use the interval timer to do some crude profiling of
my Perl program, but I discovered that the call forced by a signal
does not set whatever it is that 'caller' reads.  Can this be fixed?

More specifically, the program

    #! /usr/local/bin/perl

    &setup_profile;

    for (;;) {
	    for ($i = 0; $i < 100; $i++) {}
	    print "tick\n";
    }

    package profile;

    sub main'setup_profile {
	    $SYS_setitimer = 83;
	    $ITIMER_PROF = 2;
	    $interval = 1;

	    local($value) = pack('LLLL', $interval, 0, $interval, 0);

	    $main'SIG{'PROF'} = "profile'report";

	    syscall($SYS_setitimer, $ITIMER_PROF, $value, 0) &&
		    die "syscall() failed";
    }

    sub report {
	    print "profile ", join(' ', caller), "\n";
    }

gives the output (on Perl 3.44):

    tick
    tick
    tick
    tick
    tick
    tick
    tick
    tick
    tick
    There is no caller at tick line 26.

Dale

Dale Worley		Compass, Inc.			worley@compass.com
--
Gag me with a BITNET!