JEP 248: Make G1 the Default Garbage Collector

charlie hunt charlie.hunt at
Mon Jun 1 18:25:28 UTC 2015

> On Jun 1, 2015, at 12:54 PM, Ben Evans <ben at> wrote:
>>>> One question that may be worth pondering … suppose G1 happened to be the default GC today, and there was a JEP to make Parallel GC the default GC. What would your reaction to that JEP be?  I’m asking that question since I’d like to get a sense if your concerns are more about conservatism (not wanting to change behavior), stability of G1 or otherwise.
>>> Primarily conservatism. Of course, if G1 had been default, the
>>> "unknown unknowns" would have been resolved by now, so there would be
>>> no need to worry.
>>> I think that if G1 was default, and the platform was as successful
>>> across the same range of workloads as it is today, I'd be advocating
>>> for no change.
>> Is that because you think G1 would offer a better out of the box experience than Parallel GC, or because you would not want to see a change made to the JVM’s default GC?
> I would not want to see a change made to the default behaviour that
> could potentially negatively affect a large number of apps and in
> doing so harm the long-term perception of the platform as a "safe pair
> of hands”.

And you also realize there could be a certain number (maybe as many as, or more) applications that could realize a better out of the box experience with G1 as the default versus Parallel GC being the default?  Implying of course that the “safe pair of hands” would have a better experience.


> Thanks,
> Ben
> -- 
> Ben Evans, Co-founder jClarity @jclarity

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