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

Groups > comp.lang.java.programmer > #20978

Re: single instance

From "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org>
Newsgroups comp.lang.java.programmer
References <iah6e8hb9ssp4q46ukh3scb81bjb9fdq1k@4ax.com><sm7be8dvh8ulkncsrh3s5a1f0a0h3d6ah3@4ax.com><ml38v8maw1s1$.1gx93ez99j3rq$.dlg@40tude.net> <kc4rpu$4at$1@localhost.localdomain>
Subject Re: single instance
Date 2013-01-05 12:48 +0000
Message-ID <PNidnQgKw5vavHXNnZ2dnUVZ8t-dnZ2d@bt.com> (permalink)

Show all headers | View raw

Martin Gregorie wrote:

> A common approach for *NIXen is to use a file with a known absolute
> pathname that contains the process PID. The clever trick is that the
> program that creates the file immediately closes and reopens it for
> reading and then deletes the file without closing it: this works because
> file deletion is deferred until there are no longer any processes that
> have the file open. When a process dies or is killed, all the files it
> had open are closed.

I don't believe this would work on any variant on *NIX that I've used.  When a 
process deletes a file that it (or some other) process has open, then the file 
handles stay valid, but the /filename/ is removed from the file system, the 
file itself remaining on-disk, but no longer accessible.  (More accurately, 
/that/ filename is removed from the FS, there may well be other links to the 
same physical file with different names elsewhere.  Once all the links have 
gone, and all the processes have either died or closed their open file 
descriptors, the physical file is removed from the disk).

This is an old technique for generating almost perfectly reliable temporary 
files, but it can't work for creating /shared/ temporary files (without a lot 
more work and co-ordination between processes) precisely because the file 
becomes "invisible" as soon as it is unlinked.

There may be something added to modern Linux (or whatever) that makes it easier 
to create shared temporary files (not the requirement here, of course).  But 
there's nothing in "classic" *NIX (say from around the time of SysV).

    -- chris

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-01 12:23 -0800
  Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-01 16:40 -0500
    Re: single instance Robert Tomsick <robert+usenet@tomsick.net> - 2013-01-03 01:20 -0500
  Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-03 00:55 -0800
    Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-03 19:31 -0800
      Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-03 19:49 -0800
      Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-03 19:56 -0800
        Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-04 12:18 -0500
          Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-04 10:22 -0800
            Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-04 13:44 -0500
              Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-04 11:03 -0800
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-04 14:12 -0500
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 21:56 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 19:22 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:23 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:43 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:47 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:51 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:24 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:46 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:58 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 21:08 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 21:19 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 21:31 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 21:41 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 22:00 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 22:11 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-07 00:23 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-02-24 18:20 -0500
                Re: single instance Joshua Cranmer <Pidgeot18@verizon.invalid> - 2013-01-06 21:39 -0600
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-07 00:30 -0500
                Re: single instance lipska the kat <lipskathekat@yahoo.co.uk> - 2013-01-07 08:53 +0000
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-02-24 18:18 -0500
                Re: single instance lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-25 08:31 +0000
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-02-24 18:17 -0500
                Re: single instance Lew <lewbloch@gmail.com> - 2013-01-06 17:32 -0800
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:47 -0500
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:53 -0500
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 21:01 -0500
          Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 21:59 -0500
            Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 19:34 -0500
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:00 -0500
  Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-03 07:12 -0800
    Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-03 09:56 -0800
      Re: single instance Martin Gregorie <martin@address-in-sig.invalid> - 2013-01-03 21:05 +0000
        Re: single instance Martin Gregorie <martin@address-in-sig.invalid> - 2013-01-03 22:08 +0000
        Re: single instance "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-01-05 12:48 +0000
          Re: single instance Martin Gregorie <martin@address-in-sig.invalid> - 2013-01-05 17:43 +0000
            Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-05 09:49 -0800
            Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-05 13:02 -0500
              Re: single instance Martin Gregorie <martin@address-in-sig.invalid> - 2013-01-05 20:29 +0000
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-05 19:07 -0800
                Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-06 20:04 -0500
            Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 21:40 -0500
    Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 22:10 -0500
      Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-05 19:49 -0800
        Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-05 23:09 -0500
          Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 11:00 -0500
            Re: single instance Lew <lewbloch@gmail.com> - 2013-01-06 09:41 -0800
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-06 20:41 -0500
        Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 22:51 -0800
          Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 23:12 -0800
            Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-15 23:49 -0800
          Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 23:16 -0800
            Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-15 23:52 -0800
            Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-16 08:46 -0800
              Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 10:46 -0800
                Re: single instance markspace <markspace@nospam.nospam> - 2013-01-16 13:01 -0800
                Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-16 17:10 -0800
          Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 23:50 -0800
            Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-16 00:13 -0800
              Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 02:48 -0800
                Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-16 07:28 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 10:46 -0800
                Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-16 16:53 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 23:44 -0800
                Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-17 07:03 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-17 14:25 -0800
                Re: single instance Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-17 16:31 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-17 22:11 -0800
                Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-17 22:36 -0800
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-16 13:34 -0500
          Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-16 08:45 -0800
          Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-16 13:29 -0500
            Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-16 17:14 -0800
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-16 20:20 -0500
              Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-16 23:52 -0800
              Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-17 01:44 -0800
        Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-18 01:47 -0800
          Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-18 20:50 -0800
            Re: single instance Roedy Green <see_website@mindprod.com.invalid> - 2013-01-20 00:53 -0800
              Re: single instance Lew <lewbloch@gmail.com> - 2013-01-20 12:00 -0800
                Re: single instance Knute Johnson <nospam@knutejohnson.com> - 2013-01-20 13:33 -0800
                Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-02-24 18:12 -0500
              Re: single instance Arne Vajhøj <arne@vajhoej.dk> - 2013-01-20 21:33 -0500
      Re: single instance "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-01-06 13:34 +0000
  Re: single instance Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-01-04 10:26 -0800
    Re: single instance Twirlip of the Mists <twirlip@killfile.me.now.invalid> - 2013-01-04 14:04 -0500
  Re: single instance stledger@lanl.gov - 2013-01-16 14:51 -0800
    Re: single instance stledger@lanl.gov - 2013-01-16 15:09 -0800

csiph-web