JEP proposed to target JDK 11: 318: Epsilon: An Arbitrarily Low-Overhead Garbage Collector (original) (raw)

Aleksey Shipilev shade at redhat.com
Wed Jan 17 10:15:42 UTC 2018

On 01/17/2018 11:12 AM, Roman Kennke wrote:

Am 17.01.2018 um 11:03 schrieb Andrew Dinn:

On 17/01/18 09:43, Aleksey Shipilev wrote:

How very unpoetical :) Epsilon has the origin story for its name, see the JEP. Most people, including prospective users, know this feature under "Epsilon" and some expressed the love for the name. So, as long as there is no overwhelming amount of strong opinions against it, I'd keep the name as is. "With arbitrarily large TLABs and arbitrarily large heap, the latency overhead can be described by an arbitrarily low positive value, hence the name."

Much as I relish poetry in engineered artefacts I am willing to accept it as optional (now, as to elegance, that's another matter). However, I agree with Aleksey that this case is more than just poetry trumping the prosaic. The name declares a significant property of epsilon, affirming that GC overheads can be removed for specific uses by suitable (hw and sw) configuration but, unlike NoGC, making no claim that they can be simply ignored. Oh, also ... poetry! Why not also add -XX:+UseNoGC as alias for -XX:+UseEpsilonGC ? :-)

I think it would unprecedented to have aliases for exactly the same GC implementation?

But tell you what, if we rename to -XX:+UseNoGC, this obviously tells the users what is the consequence of using the collector. So, the part of JEP that has to "Expectations" that guard from accidental enabling with experimental/diagnostic flag stops being that relevant. Therefore, -XX:+UseNoGC can and should be available in product builds under product option! :)

-Aleksey

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