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From Gregory Shimansky <gshiman...@gmail.com>
Subject Re: [jira] Created: (HARMONY-4511) [drlvm][jvmti][gc] GC_gen doesn't collect tagged objects
Date Mon, 23 Jul 2007 09:46:03 GMT
Xiao-Feng Li wrote:
> Eugene, what are tagged objects? are they non-reachable objects?

Tags are JVMTI attributes that may be assigned to an object using 
SetTag() JVMTI function. These attributes may be used by heap profiler 
to analyze it. Tagged objects may be reachable or not, those that aren't 
reachable should be collected by GC. Take a look at JVMTI spec section 
that describes heap iteration API [2].

In JVMTI code tags to objects are implemented as a pair of jlong and 
object reference. These object references are enumerated as weak (see 
file jvmti_tags.cpp) using gc_add_weak_root_set_entry() so GC should not 
have a problem removing unreachable objects.

[1] http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#SetTag
[2] http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#Heap

> On 7/21/07, Eugene S. Ostrovsky (JIRA) <jira@apache.org> wrote:
>> [drlvm][jvmti][gc] GC_gen doesn't collect tagged objects
>> --------------------------------------------------------
>>                  Key: HARMONY-4511
>>                  URL: https://issues.apache.org/jira/browse/HARMONY-4511
>>              Project: Harmony
>>           Issue Type: Bug
>>           Components: DRLVM
>>          Environment: Windows x86
>>             Reporter: Eugene S. Ostrovsky
>> Objects tagged with SetTag() jvmti function are not collected by GC v5.
>> I'm not sure whether the bug is in GC or in jvmti heap iteration 
>> implementaion.
>> -- 
>> This message is automatically generated by JIRA.
>> -
>> You can reply to this email to add a comment to the issue online.


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