[#44776] [ruby-trunk - Bug #6385][Open] mtime vie File.stat(filename).utime vs File.open(filename, 'r').mtime in Windows — "kolmanv (Kolman Vornovitsky)" <kolmanv@...>

9 messages 2012/05/01

[#44782] [ruby-trunk - Bug #6387][Open] 1.9.3p194 crashed on require in ubuntu — "ywen (Yi Wen)" <hayafirst@...>

12 messages 2012/05/01

[#44795] [ruby-trunk - Bug #6391][Open] Segment Fault while execute make_encmake.rb for Ruby 1.9.3 P194 ( MinGW64) — "raylinn@... (ray linn)" <raylinn@...>

13 messages 2012/05/02

[#44911] [ruby-trunk - Bug #6408][Open] DelegateClass#eql? and <=> don't work as expected — "tenderlovemaking (Aaron Patterson)" <aaron@...>

11 messages 2012/05/06

[#44951] [ruby-trunk - Feature #6414][Open] Destructuring Assignment — "edtsech (Edward Tsech)" <edtsech@...>

14 messages 2012/05/08

[#44958] [ruby-trunk - Feature #6418][Assigned] Supporing a subset of ANSI escape code on Windows — "usa (Usaku NAKAMURA)" <usa@...>

11 messages 2012/05/09

[#45035] [ruby-trunk - Bug #6433][Open] rb_thread_blocking_region(): ubf() function is executed with GVL — ibc (Iñaki Baz Castillo) <ibc@...>

12 messages 2012/05/14

[#45180] [ruby-trunk - Feature #6478][Open] BasicObject#__class__ — "trans (Thomas Sawyer)" <transfire@...>

14 messages 2012/05/22

[#45193] [ruby-trunk - Feature #6482][Open] Add URI requested to Net::HTTP request and response objects — "drbrain (Eric Hodel)" <[email protected]>

16 messages 2012/05/23

[#45198] [ruby-trunk - Feature #6483][Open] parametric map — "prijutme4ty (Ilya Vorontsov)" <prijutme4ty@...>

14 messages 2012/05/23

[#45222] [ruby-trunk - Feature #6492][Open] Inflate all HTTP Content-Encoding: deflate, gzip, x-gzip responses by default — "drbrain (Eric Hodel)" <[email protected]>

23 messages 2012/05/24

[#45252] [ruby-trunk - Feature #6499][Open] Array::zip — "prijutme4ty (Ilya Vorontsov)" <prijutme4ty@...>

14 messages 2012/05/26

[#45272] [ruby-trunk - Feature #6503][Open] Support for the NPN extension to TLS/SSL — "igrigorik (Ilya Grigorik)" <ilya@...>

13 messages 2012/05/27

[#45316] [ruby-trunk - Feature #6515][Open] array.c: added method that verifies if an Array is part of another — "lellisga (Li Ellis Galardo)" <lellisga@...>

14 messages 2012/05/30

[ruby-core:44826] [ruby-trunk - Feature #6309] Add a reference queue for weak references

From: "mame (Yusuke Endoh)" <mame@...>
Date: 2012-05-03 02:29:18 UTC
List: ruby-core #44826
Issue #6309 has been updated by mame (Yusuke Endoh).


Ah, I knew what you are proposing by seeing Javadoc:

http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/ref/ReferenceQueue.html
http://docs.oracle.com/javase/6/docs/api/java/lang/ref/WeakReference.html#WeakReference(T, java.lang.ref.ReferenceQueue)

I don't know the (real-world) use case of the feature, though.


Anyway, I mean I'd like you to create a patch written *in C*.
If there is a patch that we can review and import "as is",
I will be happy to assign this ticket to some core committers,
such as ko1 and kosaki.

-- 
Yusuke Endoh <[email protected]>
----------------------------------------
Feature #6309: Add a reference queue for weak references
https://bugs.ruby-lang.org/issues/6309#change-26401

Author: headius (Charles Nutter)
Status: Feedback
Priority: Normal
Assignee: 
Category: 
Target version: 


Most interesting uses of WeakRef are much harder to do efficiently without a reference queue.

A reference queue, as implemented by the JVM, is basically a queue into which weak references are placed some time after the object they refer to has been collected. The queue can be polled cheaply to look for collected references.

A simple example of usage can be seen in the weakling gem, with an efficient implementation of an ID hash: https://github.com/headius/weakling/blob/master/lib/weakling/collections.rb

Notice the _cleanup method is called for every operation, to keep the hash clear of dead references. Failure to have a _cleanup method would mean the hash grows without bounds.

_cleanup cannot be implemented efficiently on MRI at present because there's no reference queue implementation. On MRI, _cleanup would have to perform a linear scan of all stored values periodically to search for dead references. For a heavily used hash with many live values, this becomes a very expensive operation.

It's probably possible to implement reference queues efficiently atop the new ObjectSpace::WeakMap internals, since it already keeps track of weak references and can run code when a weak reference no longer refers to a live object.


-- 
http://bugs.ruby-lang.org/

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