Re^5: SIGHUP delivered on Windows

[BrowserUk]

Would "something" fit, for instance, a process [ Console2 ] which started our Perl process, and then delivered a Windows Message to this process, and Perl, not knowing what to do with this message, invokes the signal handler established for SIGHUP?

No. I downloaded the source for console2 and the string "SIGHUP" does not appear anywhere in it, so your log message does not come from that.

As I said, I don't believe there is any way for a perl process to ever invoke a SIGHUP handler. Which only leaves your perl script to be the source of that log message in response to some stimulus other than a sighup. (ie. user error)

[rovf]

Searching our code, I find exactly one place where we possibly invoke a SIGHUP handler, but I can't see how this could apply to my case. Maybe I'm overlooking something - could you have a look at the code below? This is the code we execute right after the start of our program, within an INIT block:

        foreach my $signame (split(' ', $Config{sig_name})) {
            if ($signum) {
                $SIG{$signame} = $signame =~ /^KILL|STOP$/
                    ? 'IGNORE'    # According to perldoc perlipc, they
+ can be ignored, but not trapped
                    : sub {
                        $SIG{$signame} = 'DEFAULT';
                        print {$_} "\n\nCaught signal $signame at ",
                            timestampHMS, "\nCalled from:\n", callchai
+n(3, 16), "\n\n"
                                for (shutdown_log_handle(), *STDOUT);

                        # We need a special handler for INT (i.e. cont
+rol-C from command line), because
                        # the default action would not call the END ha
+ndlers and hence not unregister
                        # the instance in the database. For other inte
+rrupts, we deliberatrely do NOT
                        # want it unregistered 
                        if ($signame eq 'INT') {
                            print {$_} "Turning into graceful exit\n"
                                for (shutdown_log_handle(), *STDOUT);
                            exit;
                        } else {
                            kill($signum, $$);    # proceed with norma
+l handling of signal
                        }
                    };
            }
            ++$signum;
        }

In our case, the logfiles only show the line saying a SIGHUP was received. As you can see, we *do* have a kill in this code, but it would simply rethrow the same signal.

However, there *is* some processing going on after we receive a signal. Before outputting the line to our logfile, we invoke for example the functions timestampHMS (to format the time in a nice way) and callchain (which formats a stacktrace using the Perl standard function caller</c>. While none of these functions explicitly send a signal, could it be that an exception occuring within this signal handler (or a second signal arriving by that time) could be translated somehow into a SIGHUP?

[BrowserUk]

could it be that an exception occuring within this signal handler (or a second signal arriving by that time) could be translated somehow into a SIGHUP?

I cannot see how that could happen.

Firstly, for you to get to the line where you do kill SIGHUP, $$, your process would have to have already received a SIGHUP; because you're just rethrowing it. But I am unaware of anything that would ever send you a SIGHUP.

There is the vague possibility that another Perl process could be sending your process a SIGHUP; but as far as I'm aware, any attempt to do so would simply get translated into a SIGTERM.

network sites:

[rovf]

I agree with your reasoning. That's what I thought too.

So for the time being, this has to remain a mystery. Thanks for taking the time to analyze my code.