JEP 248: Make G1 the Default Garbage Collector

Ben Evans ben at
Mon Jun 1 17:54:37 UTC 2015

>>> 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".


Ben Evans, Co-founder jClarity @jclarity

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