RFR (S): JDK-8077938: Remove TraceMarkSweep

Bengt Rutisson bengt.rutisson at oracle.com
Thu Apr 16 12:43:50 UTC 2015


On 2015-04-16 14:37, Stefan Johansson wrote:
> Hi Bengt,
>
> On 2015-04-16 11:29, Bengt Rutisson wrote:
>>
>> Hi everyone,
>>
>> Could I have a couple of reviews for this small change?
>>
>> https://bugs.openjdk.java.net/browse/JDK-8077938
>> http://cr.openjdk.java.net/~brutisso/8077938/webrev.00/
>>
> Looks good.

Thanks Stefan!

Bengt

>
> Stefan
>> The flag TraceMarkSweep logs the number for the phase in the mark 
>> sweep code. This is pure debugging code that does not give much 
>> information:
>>
>> $ java -XX:+UseSerialGC -XX:+TraceMarkSweep SysGC 10
>>  1234 1234 1234 1234 1234 1234 1234 1234 1234 1234
>>
>> This does not help much even if combined with PrintGC:
>>
>> #1: [Full GC (System.gc()) 1234 310K->310K(497024K), 0,0125369 secs]
>>
>> or PrintGCDetails:
>>
>> #1: [Full GC (System.gc()) #1: [Tenured 1234: 310K->310K(342720K), 
>> 0,0087471 secs] 310K->310K(497024K), [Metaspace: 
>> 2832K->2832K(1056768K)], 0,0088441 secs] [Times: user=0,00 sys=0,00 
>> real=0,01 secs]
>>
>> There are already trace events for the phases that include 
>> information about the time for the phase and a more readable name. 
>> Thus, I think we should remove this code.
>>
>> Thanks,
>> Bengt
>



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