RFC: Epsilon GC JEP

Aleksey Shipilev shade at redhat.com
Wed Jul 19 10:32:08 UTC 2017

On 07/19/2017 11:27 AM, Thomas Schatzl wrote:
>> Okay. I am still quite a bit puzzled why "experimental" comes with
>> any notion of supportability, compatibility, testing coverage, etc. 
> Every option that is exposed to the user in the product build is part
> of the public API, and so must be supported similar to other options.
> An experimental option is just another "official" interface to the user
> as described by the CSR wiki page [1].
> Just consider this: a security issue in an experimental option is just
> as much a security issue in the product as any other. Since we do not
> want to wait that to happen, it needs the same support and testing as
> any other.

But, but... the definition in globals.hpp:

// experimental flags are in support of features that ***are not
// part of the officially supported product***, but are available
// for experimenting with. They could, for example, be performance
// features that ***may not have undergone full or rigorous QA***, but which may
// help performance in some cases and released for experimentation
// by the community of users and developers. This flag also allows one to
// be able to build a fully supported product that nonetheless also
// ships with some ***unsupported, lightly tested***, experimental features.
// Like the UnlockDiagnosticVMOptions flag above, there is a corresponding
// UnlockExperimentalVMOptions flag, which allows the control and
// modification of the experimental flags.

(emphasis mine)

Are you saying that GC group makes that definition stronger by saying
experimental flags are like product functional-stability-wise, but not
performance-wise? So, that means GC group runs the functional testing with every
combination of experimental options?


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