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Groups > comp.lang.java.programmer > #35321

Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?)

From j4n bur53 <janburse@fastmail.fm>
Newsgroups comp.lang.java.programmer
Subject Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?)
Date 2016-08-14 12:06 +0200
Organization albasani.net
Message-ID <nopfqi$h4a$1@news.albasani.net> (permalink)
References (7 earlier) <e16p89FdmcoU1@mid.individual.net> <nompol$fqt$1@news.albasani.net> <e19h9vF37j0U1@mid.individual.net> <nopee6$efa$1@news.albasani.net> <nopes8$f45$1@news.albasani.net>

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j4n bur53 schrieb:
> Ordinary Java cannot do it, class loading is usually
> serialized by a single lock. But there are also
> parallel class loader options around.

They call this "heavy-handed" or "not sufficiently granular"
http://docs.oracle.com/javase/7/docs/technotes/guides/lang/cl-mt.html

You really need to think from another prespective about
the escalable locks. Deadlock-freeness is least of concern
at the moment.

The escalation problem is a problem inside the same thread.
So it doesn't have to do with deadlock per se. Its more a
problem of extending the transition matrix of the lock.

Of course this transition matrix takes also into account the
votes of other threads. But since we extend the transition
matrix, we allow more transitions.

But these more transitions do not considerably increase or
decrease some likelihood of deadlock-freeness. They only
allow to enlarge the atomic regions.

<>: Atomic

With RW, we would be forced to do:
<A_r_T> <A_w_T>
- or -
<A_w_T> <A_r_T>

With ERW, we can do:
<A_r_T A_w_T>
- or -
<A_w_T A_r_T>

So Robert Klemme(*) jumped to the following conclusions:

    larger atomics <=> lower deadlock-freeness

But he didn't give some concrete arguments or examples
for that. I don't believe in the above law. It could
be even vice versa.

Bye

(*)

Robert Klemme wrote (13.08.16, 23:21):
 > > Deadlock-freeness is a property of the application program
 > > that uses parallel components and some synchronization
 > > primitives.
 > Right.  But there are lock types with higher and lower likelihood of 
 > deadlocks.  As far as I can see your lock which allows escalation
 > from shared read to exclusive write is one of the kind with higher
 > likelihood.

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Thread

Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-07 18:55 +0200
  Re: Library for Escalable Locks, Slimmest API? Andreas Leitgeb <avl@logic.at> - 2016-08-08 01:10 +0000
    Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-08 09:38 +0200
      Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-08 09:47 +0200
      Re: Library for Escalable Locks, Slimmest API? Andreas Leitgeb <avl@logic.at> - 2016-08-10 14:39 +0000
        Re: Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-10 18:05 +0200
          Re: Library for Escalable Locks, Slimmest API? Lew <lewbloch@gmail.com> - 2016-08-10 17:44 -0700
            Re: Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-11 12:43 +0200
              Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-12 22:18 +0200
                Re: Library for Escalable Locks, Slimmest API? Andreas Leitgeb <avl@logic.at> - 2016-08-13 05:56 +0000
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-13 11:08 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-13 11:37 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-13 11:39 +0200
                Re: Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-13 12:27 +0200
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-13 23:21 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 11:42 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 11:50 +0200
                Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:06 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 13:08 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) Robert Klemme <shortcutter@googlemail.com> - 2016-08-14 13:45 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:01 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:01 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:07 +0200
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-14 12:13 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:25 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:36 +0200
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-14 13:41 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:45 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:49 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 13:45 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 13:48 +0200
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-14 14:29 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:56 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:59 +0200
                Re: Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-14 18:10 +0200
  Simpler requirements on the horizon! (Re: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 13:18 +0200
  I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-31 01:23 +0200
    Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) bursejan@gmail.com - 2016-08-30 16:35 -0700
      Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) bursejan@gmail.com - 2016-08-30 16:45 -0700
        Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Andreas Leitgeb <avl@logic.at> - 2016-08-31 09:23 +0000
          Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Andreas Leitgeb <avl@logic.at> - 2016-08-31 10:13 +0000
          Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-31 14:00 +0200
        Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-31 07:49 -0400
          Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-31 14:13 +0200
            Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-31 12:55 -0400
    Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-31 07:54 -0400

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