JEP 248: Make G1 the Default Garbage Collector

charlie hunt charlie.hunt at
Thu Jul 30 19:16:14 UTC 2015

On Jul 30, 2015, at 1:56 PM, mark.reinhold at wrote:
> 2015/7/30 11:04 -0700, charlie.hunt at
>> ...
>> On javac, my observation is that it tends to have a very high object
>> allocation rate, and the object lifetimes are somewhat short.  And, I
>> suppose if we think about what javac does, I suppose we can come to
>> terms as to why that’s the case. I imagine if one put forth a
>> concerted effort, javac could be improved (probably true for many apps
>> too).
> If you mean to imply that high allocation rates and short lifetimes are,
> necessarily, signs of a poorly-written application then I'll have to
> disagree.  Sure, these things can be done to extremes, but I don't think
> javac does that and I'd hate to see it re-engineered to "improve" these
> particular metrics.  It might be better just to change javac's launcher
> to specify the Parallel GC, since this is most definitely an application
> for which pause times are irrelevant.

Nope, not intended to imply high object allocation rates and short object lifetimes are poorly written apps. GCs love short lived objects!

A very high number of unnecessary object allocations is my pet peeve coupled with keeping them live for much longer than necessary.


>>       Performance of javac is certainly one we want to pay close
>> attention due to its impact to the developer use case.
> No argument there!
> - Mark

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