JEP 248: Make G1 the Default Garbage Collector

charlie hunt charlie.hunt at
Thu Jul 30 16:59:38 UTC 2015

> On Jul 30, 2015, at 11:50 AM, Andrew Dinn <adinn at> wrote:
> On 30/07/15 16:42, charlie hunt wrote:
>> While we really like hearing about experiences with G1 GC, (and the
>> other collectors as well), let’s try to keep the discussion on this
>> thread on the subject G1 GC being made the default GC for JDK 9 by
>> talking about the scenarios and the observations of those potentially
>> impacted.
> I think you miss my point which was not to share my experiences. Rather
> it was to rebut your suggestion that G1 is an inherently better GC than
> Parallel on the grounds of its heap usage by pointing out that the
> superiority of G1 in this regard is more apparent than real. I would
> hate to see us to fix whatever real problem we face by switching to a
> different default GC if it might be much better solved by adjusting the
> configuration of the existing GC.

You realize you had to tune Parallel GC to get the desired behavior?

Out of the box, G1 will do a better job. That’s my point. ;-)

How many novice users will figure out how to tune Parallel GC to get the desire behavior? Keep in mind we are talking about the population who do not specify a GC with this JEP.



> regards,
> Andrew Dinn
> -----------
> Senior Principal Software Engineer
> Red Hat UK Ltd
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> (USA), Michael O'Neill (Ireland)

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