RFR (S): 8024974 - Incorrect use of GC_locker::is_active()

Per Liden per.liden at oracle.com
Thu Sep 19 22:44:55 PDT 2013

Thanks Bengt!


On 09/19/2013 02:18 PM, Bengt Rutisson wrote:
> Hi Per,
> Looks good.
> Bengt
> On 9/19/13 8:03 AM, Per Liden wrote:
>> Webrev: http://cr.openjdk.java.net/~pliden/8024974/webrev.01/
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8024974
>> SymbolTable and StringTable can make calls to GC_locker::is_active()
>> outside a safepoint. This isn't safe because the GC_locker active
>> state (lock count) is only updated at a safepoint and only remains
>> valid as long as _needs_gc is true. However, outside a safepoint
>> _needs_gc can change to false at any time, which makes it impossible
>> to do a correct call to is_active() in that context. In this case
>> these calls can just be removed since the input argument to
>> basic_add() should never be on the heap and so there's no need to
>> check the GC_locker state. This change also adjusts the assert() in
>> is_active() to makes sure all calls to this function are always done
>> under a safepoint.
>> cheers,
>> /Per

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