RFR: 8168640: (fc) Avoiding AtomicBoolean in FileInput/-OutputStream improves startup

[Alan Bateman]

On 26/10/2016 13:11, Claes Redestad wrote:

> Hi,
>
> does this commentary suffice?
>
> http://cr.openjdk.java.net/~redestad/8168640/webrev.02/
>
> To answer Paul's question about the exact startup gain:
>
> 20 named classes observable with -Xlog:class+load (11
> additional anonymous show up in heap dumps), for example:
>
>   java.lang.invoke.MethodType$ConcurrentWeakInternSet
>   java.lang.invoke.MethodType$ConcurrentWeakInternSet$WeakEntry
>   java.lang.invoke.MethodTypeForm
>   java.lang.invoke.VarHandle$1
>   java.lang.invoke.VarHandle$AccessDescriptor
>   java.lang.invoke.VarHandle$AccessMode
>   java.lang.invoke.VarHandle$AccessType
>   java.lang.invoke.VarHandleGuards
>   java.lang.invoke.VarHandleInts$FieldInstanceReadOnly
>   java.lang.invoke.VarHandleInts$FieldInstanceReadWrite
>   java.lang.invoke.VarHandles
>   java.lang.invoke.VarHandle$TypesAndInvokers
>
> Not initializing this eagerly drops retained heap on a minimal
> Hello World by ~17Kb, and a 3-10ms startup improvement
> on similar programs (naturally varies a lot between systems
> due to timing of when/if JIT compilations happen during early
> execution).
I assume these classes will be loaded by anything non-trivial but having 
them but keeping them out of hello world/short running tools is good.

The updated webrev looks okay to me.

-Alan