[ruby-core:99674] [Ruby master Feature#6309] Add a reference queue for weak references
From:
samuel@...
Date:
2020-08-23 21:07:33 UTC
List:
ruby-core #99674
Issue #6309 has been updated by ioquatix (Samuel Williams). This still seems like a good idea. Any update? ---------------------------------------- Feature #6309: Add a reference queue for weak references https://bugs.ruby-lang.org/issues/6309#change-87161 * Author: headius (Charles Nutter) * Status: Assigned * Priority: Normal * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- 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. -- https://bugs.ruby-lang.org/ Unsubscribe: <mailto:[email protected]?subject=unsubscribe> <http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>