[ruby-core:66431] [ruby-trunk - Bug #10537] Repeated creation and garbage collection of WeakRef instances against a single object leaks memory

Issue #10537 has been updated by Eric Wong.


 Thanks, the following patch should fix it.  Your test runs much in less
 than 20s and uses 10M on my older x86-64 machine.   It took over 2
 minutes before.
 
 (lightly tested, and I'm unfamiliar with the weakmap code):
 
 --- a/gc.c
 +++ b/gc.c
 @@ -2360,6 +2360,21 @@ define_final0(VALUE obj, VALUE block)
  
      if (st_lookup(finalizer_table, obj, &data)) {
  	table = (VALUE)data;
 +
 +	/* avoid duplicate block, table is usually small */
 +	{
 +	    const VALUE *ptr = RARRAY_CONST_PTR(table);
 +	    long len = RARRAY_LEN(table);
 +	    long i;
 +
 +	    for (i = 0; i < len; i++, ptr++) {
 +		if (rb_funcall(*ptr, idEq, 1, block)) {
 +		    rb_gc_force_recycle(block);
 +		    return *ptr;
 +		}
 +	    }
 +	}
 +
  	rb_ary_push(table, block);
      }
      else {

----------------------------------------
Bug #10537: Repeated creation and garbage collection of WeakRef instances against a single object leaks memory
https://bugs.ruby-lang.org/issues/10537#change-50062

* Author: Alex Boyd
* Status: Open
* Priority: Normal
* Assignee: 
* Category: lib
* Target version: 
* ruby -v: ruby 2.2.0dev (2014-11-24 trunk 48552) [x86_64-darwin14]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
~~~
require 'weakref'
a = Object.new
1_000_000.times do
  WeakRef.new a
end
GC.start
~~~

The above results in Ruby consuming ~150 MB of RAM, all of which can only be freed by dropping `a`. This should not be the case - an object being weakly referenced should not itself hold a reference to the WeakRef (or any associated data) pointing at it.



-- 
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