sockets giving me gray hairs. server keeps dying

[lekonna]

Hi guys,
i'm having bit of a hard time getting my very simple multiplexing
socket server staying alive. It keeps exiting without giving any
messages, and since i'm running the bugger in while(1) loop i don't
quite get why the heck it does that.

Its a very basic echo server with some added features for keeping
track of users. Basicly i wanted to learn how to use sockets in flash
and needed something to echo the poo that i send back to me so i came
up with this quick and dirty solution. Now unfortunately it seems that
the trusty old work-horse perl keeps dying on me.

Heres the link to attachr with syntax highlighted version of the
server implementation.
http://attachr.com/10605

very basic server with some ugly xml hacks in it.

Is there a way to enable some sort of debug info on what actually goes
wrong?

Br,
Lekonna

 

[lekonna]

Hi guys,
i'm having bit of a hard time getting my very simple multiplexing
socket server staying alive. It keeps exiting without giving any
messages, and since i'm running the bugger in while(1) loop i don't
quite get why the heck it does that.

Its a very basic echo server with some added features for keeping
track of users. Basicly i wanted to learn how to use sockets in flash
and needed something to echo the poo that i send back to me so i came
up with this quick and dirty solution. Now unfortunately it seems that
the trusty old work-horse perl keeps dying on me.

Heres the link to attachr with syntax highlighted version of the
server implementation.http://attachr.com/10605

very basic server with some ugly xml hacks in it.

Is there a way to enable some sort of debug info on what actually goes
wrong?

Br,
Lekonna

some added specs, i ran it on 64 bit rhel 5.1
with perl servscript.pl 61003 > log.txt

 

[lekonna]

Hi guys,
i'm having bit of a hard time getting my very simple multiplexing
socket server staying alive. It keeps exiting without giving any
messages, and since i'm running the bugger in while(1) loop i don't
quite get why the heck it does that.

One thing you can do any time a program is "dying for no reason," [which
of course really means, dying for some reason that we don't yet
understand ] is to declare a DIE handler, and in the handler, write a
log message and a stack trace.

Secondly, in the same vein, your program should already be copiously
sprinkled with log messages, saying "I'm doing this," and, "I'm getting
ready to do that." Of course you will disable those messages when you
roll your code to production; but during development, and especially
during EARLY development, they are invaluable. If you had a lot of log
messages in your code, you'd know the last thing your server did before
it died.

Its a very basic echo server with some added features for keeping
track of users. Basicly i wanted to learn how to use sockets in flash
and needed something to echo the poo that i send back to me so i came
up with this quick and dirty solution. Now unfortunately it seems that
the trusty old work-horse perl keeps dying on me.

One thing I truly know in this world is that sockets work perfectly well
in Perl. I'm going to go way out on a limb here and say that the problem
is probably in your code

Heres the link to attachr with syntax highlighted version of the
server implementation.
http://attachr.com/10605

very basic server with some ugly xml hacks in it.

Is there a way to enable some sort of debug info on what actually goes
wrong?

I didn't look at your code. But if you take my suggestions to write log
messages before and after every interesting thing your program does
(startup, init, creating/opening/connecting sockets, etc.); and
implementing DIE and WARN handlers, you will soon see what's going on.
The idea is to equip your program with the means to debug itself.

One more thing that comes to mind is that people learning to write
servers often have trouble with the logic of handling a connection
request using the accept() function. To service a connection request you
have to fork a child process to handle that client; or you have to
handle the client yourself, managing multiple sockets: the listening
socket, on which you receive connection requests; and one for each
connected client. Typically you need to use non-blocking sockets in
conjunction with the select() call. [And note that "select" is very
unfortunately overloaded in Perl to a totally different function that
has the exact same name but has nothing to do with it!]

It wouldn't hurt to review your accept() logic.

Hope this helps.

Thanks for the reply, actually this implementation isn't a multi
threading one, wanted to try out an single threaded version for
change. the thing is that on my windows machine the server runs
smoothly but dies without an explanation every now and then on the
linux 64bit machine.

Since there are no exit points inside the while true loop and no error
messages are output i can only phantom that it is some kind of bug in
the actual library i'm using itself. browsed quickly through the 5.8.8
x86_64-linux-thread-multi/IO lib but couldn't find a way to enable any
more debug messages as it is.

This is a tricky one, still no solution. I do believe the problem is
in my logic but seem to be unable to find more info on where we
actually exited from.