[racket] adding other objects to custodian

From: Jakub Piotr Cłapa (jpc-ml at zenburn.net)
Date: Mon Jul 5 19:26:01 EDT 2010

On 04.07.10 04:03, Neil Van Dyke wrote:
> I want to be sure that a host OS subprocess created with "subprocess" is
> killed when thread of my program in which it was created terminates.
> Currently, I create a custodian for the thread and explicitly call
> "custodian-shutdown-all" at the end of the thread's lifetime (in a
> "dynamic-wind" cleanup thunk).

In my experience with Windows and UNIX I found that it is best to make 
the subprocess die on stdin EOF or error. This automatically handles 
dying ssh sessions (for remote processes) and dying racket. As a bonus 
this probably is what you want (and what most truly UNIX programs do 
themselves [1]).

This is a problem with long-running, output-only programs (I wrote 
several such programs for decoding unsolicited serial port data from 
multimeters) but you can solve it by spawning a thread which hangs on 
read() and calls exit() afterwards.

[1] DJB has some nice stories about "UNIX" daemons and their authors 
funny ideas:

Jakub Piotr Cłapa

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