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Re: Why does the Front End freeze when using a TCPIP-mode connection with the kernel?

• To: mathgroup at smc.vnet.net
• Subject: [mg124005] Re: Why does the Front End freeze when using a TCPIP-mode connection with the kernel?
• From: John Fultz <jfultz at wolfram.com>
• Date: Thu, 5 Jan 2012 05:56:26 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Reply-to: jfultz at wolfram.com

I don't know if this is the cause of the problem or not, but that's the wrong 
linkname syntax for the TCPIP protocol.  TCPIP uses *two* ports, 
comma-delimited.  One is the regular data channel, and the other is for urgent 
"messages", which includes things like interrupt, abort, and terminate.

Try doing...

LinkCreate[LinkProtocol -> "TCPIP"]

to see an example of a proper linkname.

Sincerely,

John Fultz
jfultz at wolfram.com
User Interface Group
Wolfram Research, Inc.

On Wed, 4 Jan 2012 05:01:45 -0500 (EST), Szabolcs Horvát wrote:
>
> Note: I already asked this question here, but I'm hoping to reach a
> larger audience:
>
> http://stackoverflow.com/questions/8717211/understanding-kernel-frontend-
> communication-why-does-my-front-end-freeze
>
>
> The question:
>
> When I try to connect to a remote kernel, the front end always freezes
> sooner or later.  I managed to reproduce the problem on the *local*
> machine.  Can you please take a look at what I am doing wrong, and how I
> can prevent the problem?
>
> Here's how to reproduce the problem on a single machine (no remote
> connection needed):
>
> 1. Create a new kernel configuration (Evaluation menu -> Kernel
> Configuration Options...)
>
> Select Advanced Options.
>
> Arguments to MLOpen:
>
> -LinkName "8000@YOUR-IP-HERE" -LinkMode Listen
> -LinkProtocol TCPIP -LinkHost "YOUR-IP-HERE"
> -LinkOptions MLDontInteract
>
> (Replace YOUR-IP-HERE with your computers IP address. On Windows
> you can get this by typing ipconfig in a command window.)
>
> Shell command to launch kernel: leave empty (we will do it manually)
>
> 2. Open a new notebook, set the notebook's kernel to the one you
> just set up, and evaluate something (1+1).
>
> 3. Now we need to launch the kernel manually, before the connection
> times out (do it quickly). So start a new kernel (math) in command line
> mode, and evaluate the following:
>
> link==LinkConnect["8000",LinkProtocol->"TCPIP"] (* connect to front
> end link *)
>
> $ParentLink == link (* set the front end link as parent link *)
>
> Now the connection is established, and everything appears to work
> correctly (save for the one message in the front end's pink message
> window)
>
> 4. Evaluate Manipulate[n, {n, 0, 100, 1}]. This appears to work too.
> Now play with the slider. Sooner or later the front end will freeze and
> needs to be killed. For me, dragging the slider up and down for ~10
> seconds without releasing it always suffices.
>
> Why does the Front End freeze? How can I create a TCPIP-mode connection
> between the front end and the kernel in a way that everything will be
> working correctly?
>
> Note: I am on Windows XP.  I should also link to this presentation and
> package here: http://library.wolfram.com/infocenter/Conferences/7250/
> When I use this package, I get the same freeze.
>
>
> --
> Szabolcs Horv=E1t
> Mma QA site proposal: http://area51.stackexchange.com/proposals/37304