I solved the problem quite simply. First, I read the fscking manual a third time and I noticed that while I was autoflushing the buffer on STDOUT, I wasn't flushing the buffer on the filehandle.

I fixed this by using autoflush on the filehandle:

open (LOGFILE, ">tempLog.$time" ) || die "Cannot open tempLog for writ
+ing: $!\n";
autoflush LOGFILE 1;
print LOGFILE "Socket server started on port $port at ", localtime, "\
+n";
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use strict;

my $file;
open($file, ">abc");
my $ret = fork;
if ($ret) {
    print $file "log from parent\n";
    sleep(5);
    close($file);
} else {
    print $file "log from child\n";
}
[download]

I solved the problem of when to close by trapping for close signals from the terminal (kill -1, kill -9) and including close handles in the event handler.

If you make something idiot-proof, eventually someone will make a better idiot.
I am that better idiot.