RFR 8251118: BiasedLocking::preserve_marks should not have a HandleMark

[Patricio Chilano]

On 8/11/20 5:29 PM, Harold Seigel wrote:
> Hi Patricio,
>
> I think your modifications of TestFullGCALot.java are fine for testing 
> your fix.  No need for a brand new test.
Great, thanks for reviewing this Harold!


Patricio
> Thanks, Harold
>
> On 8/11/2020 4:11 PM, Patricio Chilano wrote:
>> Hi Harold,
>>
>> Thanks for looking at this.
>>
>> On 8/11/20 4:11 PM, Harold Seigel wrote:
>>> Hi Patricio,
>>>
>>> The fix looks good.  Could you also add a test based on the failure 
>>> discussed in the bug description?
>> Sure. From the mach5 job I run without the patch I see that 
>> test/hotspot/jtreg/gc/TestFullGCALot.java fails pretty much 
>> consistently on all platforms and tiers 1-3. What do you think about 
>> adding a new run on that test with -XX:+UseBiasedLocking? Change 
>> would be:
>>
>> diff --git a/test/hotspot/jtreg/gc/TestFullGCALot.java 
>> b/test/hotspot/jtreg/gc/TestFullGCALot.java
>> --- a/test/hotspot/jtreg/gc/TestFullGCALot.java
>> +++ b/test/hotspot/jtreg/gc/TestFullGCALot.java
>> @@ -26,8 +26,9 @@
>>  /*
>>   * @test TestFullGCALot
>> - * @bug 4187687 8187819
>> + * @bug 4187687 8187819 8251118
>>   * @summary Ensure no access violation when using FullGCALot
>>   * @requires vm.debug
>>   * @run main/othervm -XX:NewSize=10m -XX:+FullGCALot 
>> -XX:FullGCALotInterval=120 gc.TestFullGCALot
>> + * @run main/othervm -XX:NewSize=10m -XX:+FullGCALot 
>> -XX:FullGCALotInterval=120 -XX:+UseBiasedLocking gc.TestFullGCALot
>>   */
>>
>> I would suggest adding a new run to FieldMonitor.java with 
>> -XX:+UseBiasedLocking instead, but it doesn't fail as consistently.
>>
>> Alternatively a new test would be pretty much like 
>> TestFullGCALot.java. The only change I would make is to explicitly 
>> add a synchronized statement:
>>
>> /*
>>  * @test TestFullGCOnSync
>>  * @bug 8251118
>>  * @run main/othervm -XX:NewSize=10m -XX:+FullGCALot 
>> -XX:FullGCALotInterval=120 -XX:+UseBiasedLocking TestFullGCOnSync
>>  */
>>
>> public class TestFullGCOnSync {
>>   public static void main(String args[]) throws Exception {
>>     Integer x = new Integer(10);
>>     synchronized (x) {
>>       System.gc();
>>       System.out.println("Hello world!");
>>     }
>>   }
>> }
>>
>> Thanks,
>> Patricio
>>> Thanks, Harold
>>>
>>> On 8/11/2020 2:11 PM, Patricio Chilano wrote:
>>>> Hi all,
>>>>
>>>> Please review the following small fix which involves removing the 
>>>> added HandleMark in BiasedLocking::preserve_marks():
>>>>
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8251118
>>>> Webrev: http://cr.openjdk.java.net/~pchilanomate/8251118/v1/webrev/
>>>>
>>>> I've inspected the callers of BiasedLocking::preserve_marks() and 
>>>> they all have an assert that the current thread is the VMThread. 
>>>> Since the VMThread creates a HandleMark object before executing a 
>>>> VM operation the extra HandleMark added in 8249192 is not needed.
>>>> I've run tiers1-3 in mach5 with -XX:+UseBiasedLocking and without 
>>>> the patch I get several crashes in BiasedLocking::restore_marks(). 
>>>> With the patch tests completed successfully.
>>>>
>>>> Thanks,
>>>> Patricio
>>>>
>>