JEP 248: Make G1 the Default Garbage Collector (original) (raw)

Ben Evans ben at jclarity.com
Fri Jun 5 09:50:15 UTC 2015

(Resend from the account that's actually subscribed to hotspot-dev ...) Hi Mark & Charlie,

Thanks for the summary.

I'm cautiously optimistic about the plan - but I would like a bit more of an idea of what quantitative data & experiences we would need to prove whether G1 was ready or not.

I've conducted a survey of apps via the user groups & should have some data on how many apps run with default collectors later on today.

Thanks,

Ben

On Thu, Jun 4, 2015 at 11:08 PM, <mark.reinhold at oracle.com> wrote:

2015/6/4 6:44 -0700, charlie.hunt at oracle.com:

Wanted to come back to this thread, continue the dialog, reiterate the objective, (try to) summarize the concerns and put forth a potential plan for this JEP going forward.

Intent: Use G1 GC as the default collector chosen by the JVM when no GC is explicitly set at the JVM command line. ... Charlie -- thanks for the excellent summary of this wide-ranging discussion! ... Suggested plan for moving forward: - Make G1 the default collector in JDK 9, continue to evaluate G1 and enhance G1 in JDK 9 - Mitigate risk by reverting back to Parallel GC before JDK 9 goes “Generally Available” (Sept 22, 2016 [1]) if warranted by continuing to monitor observations and experiences with G1 in both JDK 9 pre-releases and latest JDK 8 update releases - Address enhancing ergonomics for selecting a default GC as a separate JEP if future observations suggests its needed I think this is a fine plan. Stefan -- To move forward with JEP 248, could you please revise the second item in the "Risks and Assumptions" section to note that there is some concern that G1 might not be ready to become the default, that making it the default now will allow us to get more feedback on it, and that if it proves to be not ready then we'll revert the default to the Parallel GC in time for JDK 9 GA? Ben -- Can you live with this plan? - Mark

-- Ben Evans, Co-founder jClarity @jclarity

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