Daemon won't process request until next

shotgunefx has asked for the wisdom of the Perl Monks concerning the following question:

I've run into a strange problem with a forking daemon I've written. It uses HTTP::Daemon.

The daemon code has been running stable for well over a year. I wanted to move it to another linux machine and I've run into an odd problem.

On the new system, the daemon won't answer a request until another request comes. The daemon is fairly involved and breaking out a minimum case example might take a bit.

I've compared the output from the two demons and it given the same request, the server responds with the same content byte-wise. This hanging does not happen when I telnet in and type the request manually. I thought it might be an LWP issue (That's what I was using to make the requests) but lynx is doing the same thing.

Anyone have an idea on what could possibly cause this behaviour to narrow where I should start looking? It would be greatly appreciated.

-Lee

"To be civilized is to deny one's nature."

Comment on Daemon won't process request until next

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Re: Daemon won't process request until next by jsprat (Curate) on Jul 16, 2003 at 20:44 UTC
You may want to try LWP::Debug with each of the servers to see what's different (if anything) between the connections. BTW, which version(s) of perl, LWP, and HTTP::Daemon (+ any other modules) are you using? Are they the same versions on the new server as the old server? If you replace one at a time, how does it affect the problem? HTH...	[reply]
Re: Daemon won't process request until next by sgifford (Prior) on Jul 16, 2003 at 20:23 UTC
I would debug this either with the Perl debugger, by inserting a lot of `print` statements and seeing where the daemon is getting stuck, or else with `strace`. I know that's rather obvious and perhaps unhelpful, but without any details whatsoever the only other option is wild guessing...	[reply] [d/l]
Re: Re: Daemon won't process request until next by shotgunefx (Parson) on Jul 17, 2003 at 09:21 UTC
Nothing wrong with stating the obvious. I tried the print route. I compared the output of the manually typed telnet request and the lynx/lwp requests and they all have the same exact byte per byte, input and output. Basically get_request() is not seeing the last line of the request until another request comes in.I think it's an IO::Handle thing. The machine with the problem was just for testing. I've run it on other machines since without problems so probably some deep crusty socket problem. Maybe a bad header or something. Either way I just gave up as the test machine is about to get it's OS replaced. -Lee "To be civilized is to deny one's nature."	[reply]
Re: Daemon won't process request until next by Thelonius (Priest) on Jul 16, 2003 at 19:50 UTC
Well autoflushing is on by default. It seems like there might be a bug in get_request. I'm fairly confounded here. Flushing is not enough. You must close your handles. Your response is not over until the socket is closed. That's how HTTP works.	[reply]
Re: Re: Daemon won't process request until next by sgifford (Prior) on Jul 16, 2003 at 20:20 UTC
...assuming you're not using keep-alive.	[reply]
Re: Re: Daemon won't process request until next by shotgunefx (Parson) on Jul 16, 2003 at 20:34 UTC
I am aware of this. Indeed the socket is getting closed. It seems to be a bug in HTTP::Daemon or one of the socket libraries as I have now tried it on 3 other machines without problems. Only this one machine. F**king hate problems like this, sigh. Thanks, -Lee "To be civilized is to deny one's nature."	[reply]
Re: Re: Re: Daemon won't process request until next by waswas-fng (Curate) on Jul 16, 2003 at 22:45 UTC
Do your versions of perl or HTTP::Daemon differ on this box? -Waswas	[reply]
Re: Re: Re: Re: Daemon won't process request until next by shotgunefx (Parson) on Jul 17, 2003 at 09:27 UTC
Re: Daemon won't process request until next by Aristotle (Chancellor) on Jul 16, 2003 at 18:27 UTC
I don't have any idea what I'm talking about, but the symptoms do sound like some sort of buffering issue. Make sure you close/flush any handles ASAP? Makeshifts last the longest.	[reply]
Re: Re: Daemon won't process request until next by shotgunefx (Parson) on Jul 16, 2003 at 18:53 UTC
Well autoflushing is on by default. It seems like there might be a bug in get_request. I'm fairly confounded here. -Lee "To be civilized is to deny one's nature."	[reply]