Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.arch.embedded > #12713

Re: Resource revocation

From Paul Rubin <no.email@nospam.invalid>
Newsgroups comp.arch.embedded, comp.realtime
Subject Re: Resource revocation
Date 2013-07-25 19:38 -0700
Organization Nightsong/Fort GNOX
Message-ID <7xr4emjbaq.fsf@ruckus.brouhaha.com> (permalink)
References <ksrtvv$kmp$1@speranza.aioe.org> <7xehame7ut.fsf@ruckus.brouhaha.com> <kss75t$dgh$1@speranza.aioe.org>

Cross-posted to 2 groups.

Show all headers | View raw

Don Y <this@isnotme.com> writes:
> I don't see how reliance on a particular language keyword or OS hook
> would matter when considering the way in which this *functionality* is
> availed to the developer.

Different languages and OS's lend themselves to different styles.  The
application's requirements also matter.  E.g. the Erlang approach to
infrequent failures (which this resource being preempted might amount
to) is to just let the failing process crash, and restart it through
supervision.  That might not be ok if you can't tolerate a few
milliseconds of delay doing that stuff now and then.

> But, there are noticeable differences (and attendant risk) with each
> of the following *different* "stylistic" approaches to the problem:
> ...

Most of those don't seem to handle the issue of the resource being
preempted while the process in question is trying to use it.

>> http://jlouisramblings.blogspot.com/2012/08/getting-25-megalines-of-code-to-behave.html

> I didn't see anything in there germane to my question.  Did I miss
> something? 

I don't know if you missed anything.  The article suggests uses message
passing for concurrency.  In that scheme, each task typically is
organized as a synchronous event loop where each pass through the loop
happens rather quickly.  In that situation, resource preemption can just
be a matter of sending a message saying the process with the resource
must be released.  

Most of my stuff is coded in that style these days.  One drawback is
that it tends to use more threads than a traditional approach would, so
there is a memory and context switching cost.  I don't know if that's an
issue for you.  It does seem easier (at least to me) to keep stuff
straight with this approach, with fewer ways to go wrong.

Or, as you say, you can just kill the target process, in which case it
helps if the OS or runtime environment automatically reclaims the
resource you wanted.  Again under Erlang, the runtime has a nice
framework for restarting killed processes.  You could have a priority
queue of processes waiting to acquire the resource.  So if the resource
must be preempted, the preempting process puts in a high priority
request, then kills the process with the resource, which (on restart)
tries to get the resource back, but (since it has lower priority) it has
to wait for the preempting process to finish.

Back to comp.arch.embedded | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Resource revocation Don Y <this@isnotme.com> - 2013-07-25 12:23 -0700
  Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-25 12:51 -0700
    Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-25 15:00 -0700
      Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-25 19:38 -0700
        Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-25 22:12 -0700
          Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-25 23:37 -0700
            Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 01:13 -0700
              Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 02:48 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 04:19 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 09:46 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 10:21 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 19:30 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 11:56 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 20:08 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 13:11 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 12:31 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 11:08 -0700
                Re: Resource revocation Rob Gaddi <rgaddi@technologyhighland.invalid> - 2013-07-29 09:16 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-29 10:22 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 11:22 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 08:56 -0700
                Re: Resource revocation Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2013-07-26 19:25 +0200
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 10:51 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 19:21 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 11:50 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 19:42 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 12:43 -0700
                Does the Buddha have a real time nature? ;)  (was Resource revocation) Roberto Waltman <usenet@rwaltman.com> - 2013-07-26 17:06 -0400
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Don Y <this@isnotme.com> - 2013-07-26 17:12 -0700
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 09:44 +0100
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 09:45 +0100
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Don Y <this@isnotme.com> - 2013-07-27 12:28 -0700
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2013-07-27 14:11 +0200
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 12:40 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 21:29 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 13:52 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 22:55 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 17:22 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 10:02 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 09:29 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 18:20 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 12:48 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 22:57 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 16:18 -0700
                Re: Resource revocation Roberto Waltman <usenet@rwaltman.com> - 2013-07-31 16:33 -0400
                Re: Resource revocation upsidedown@downunder.com - 2013-07-27 22:53 +0300
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 22:42 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 16:41 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 16:49 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-28 08:39 +0300
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 23:11 -0700
                Re: Resource revocation Roberto Waltman <usenet@rwaltman.com> - 2013-07-31 16:15 -0400
                Re: Resource revocation upsidedown@downunder.com - 2013-08-01 00:13 +0300
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 15:16 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 23:05 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 15:37 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 23:38 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 16:08 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-28 01:16 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 18:43 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-28 09:01 +0300
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 15:21 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 23:07 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 12:00 -0700
                Re: Resource revocation stephenXXX@mpeforth.com (Stephen Pelc) - 2013-07-27 16:49 +0000
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-28 18:31 -0400
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-28 15:51 -0700
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-28 20:12 -0400
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-28 18:35 -0700
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-29 00:10 -0400
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 00:23 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-29 01:05 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 12:07 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-30 01:11 +0300
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 15:20 -0700
                Re: Resource revocation Rob Gaddi <rgaddi@technologyhighland.invalid> - 2013-07-29 15:42 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 16:41 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-30 08:51 +0300
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-30 09:09 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 01:30 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-30 10:04 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-30 02:55 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 07:12 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-30 16:59 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 13:17 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-30 10:12 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-30 18:48 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 20:18 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-31 09:27 +0300
                Re: Resource revocation [long] Don Y <this@isnotme.com> - 2013-07-31 00:47 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-30 02:50 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-30 13:22 +0300
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 07:24 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 01:17 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-29 19:28 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-29 11:40 +0300
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 11:44 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-29 20:56 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 13:16 -0700
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-30 00:08 -0400
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 23:41 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-31 00:58 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-31 10:18 -0700
                Re: Resource revocation George Neuner <gneuner2@comcast.net> - 2013-08-02 06:19 -0400
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-08-03 02:26 -0400
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-28 19:31 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 00:44 -0700
  Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-25 22:42 -0400
    Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-25 22:12 -0700
  Re: Resource revocation "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2013-07-31 13:41 +0200
    Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-31 07:51 -0700
      Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-31 08:07 -0700
        Re: Resource revocation Anders.Montonen@kapsi.spam.stop.fi.invalid - 2013-07-31 15:55 +0000
          Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-31 10:18 -0700
      Re: Resource revocation "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2013-08-01 14:42 +0200
        Re: Resource revocation Don Y <this@isnotme.com> - 2013-08-01 14:34 -0700
      Re: Resource revocation upsidedown@downunder.com - 2013-08-02 09:08 +0300
        Re: Resource revocation Don Y <this@isnotme.com> - 2013-08-02 07:26 -0700

csiph-web