RFR: 8065331: Add JVM trace events for failed allocations

Marcus Larsson marcus.larsson at oracle.com
Wed Apr 8 15:05:02 UTC 2015


Hi again,

During offline discussions with Erik Helin we decided to skip the 
gc-attempt counter altogether, since this information had little value. 
Also, as the "Collect for allocation" event would always be accompanied 
by the (already existing) garbage collection events, this event is 
unnecessary and has been removed as well. Instead, to see allocations 
pending a particular GC, one can look at "Allocations requiring GC" 
events preceding the garbage collection event sent for that GC.

New (significantly smaller) webrev:
http://cr.openjdk.java.net/~mlarsson/8065331/webrev.02/

Thanks,
Marcus


On 04/02/2015 02:55 AM, Marcus Larsson wrote:
> Hi Jon,
>
> Thank you for looking at this.
>
> The way I intended the gc count information to be useful is to indicate if/when allocations keep failing. Problematic allocations would then have a gc count higher than 1. It's not really critical that this is the exact total, as it's just an indication, so a partial GC count could work I guess. If you think it would be better I can take a look at how I can reduce the CR by being less precise with this counter.
>
> Thanks,
> Marcus
>
> ----- Original Message -----
> From: jon.masamitsu at oracle.com
> To: hotspot-gc-dev at openjdk.java.net
> Sent: Wednesday, 1 April, 2015 4:44:30 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
> Subject: Re: RFR: 8065331: Add JVM trace events for failed allocations
>
> Marcus,
>
> These changes are rather extensive and the CR is rather thin
> on details.  How will the GC count information be useful?
> Is it critical that it be the total GC count for failed allocation?
> Could some partial GC count that does not require such
> extensive changes be almost as useful?
>
> Thanks.
>
> Jon
>
> On 3/30/2015 3:54 PM, Marcus Larsson wrote:
>> Ping!
>>
>> ----- Original Message -----
>> From: marcus.larsson at oracle.com
>> To: hotspot-gc-dev at openjdk.java.net
>> Sent: Tuesday, 24 March, 2015 7:35:08 AM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
>> Subject: RFR: 8065331: Add JVM trace events for failed allocations
>>
>> Hi,
>>
>> Please review the following patch adding new trace events for allocations requiring GC, and GCs triggered by allocation. See the JEP for a description of these two new events.
>>
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8065331
>>
>> Webrev:
>> http://cr.openjdk.java.net/~mlarsson/8065331/webrev.00/
>>
>> JEP:
>> https://bugs.openjdk.java.net/browse/JDK-8060092
>>
>> Tests:
>> jprt, jtreg
>>
>> Thanks,
>> Marcus



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