RFR: 8246241: LambdaFormEditor should use a transform lookup key that is not a SoftReference

[Claes Redestad]

On 2020-06-01 20:48, Paul Sandoz wrote:
> Looks good. I sent some trivial comments offline.

Thanks!

Adjusted the webrev in-place based on your comments (A few methods were
public that should be private, etc..)

/Claes
> 
> Paul.
> 
>> On Jun 1, 2020, at 4:07 AM, Claes Redestad <claes.redestad at oracle.com> wrote:
>>
>> Hi,
>>
>> the LambdaFormEditor uses a SoftReference-based cache to avoid
>> generating LambdaForms we have already generated. By introducing a
>> lookup key that is not a SoftReference we can improve this by allocating
>> less up front and by inducing less work for the GC later on.
>>
>> I also refactored a few cases where I had neglected to add a static
>> factory method to create the Transform (now TransformKey). For the
>> transform types affected this helps further reduce allocations.
>>
>> Bug:    https://bugs.openjdk.java.net/browse/JDK-8246241
>> Webrev: http://cr.openjdk.java.net/~redestad/8246241/open.00/
>>
>> Testing: tier1-2, java/lang/invoke locally with STRESS_TEST=true
>>
>> Verified a speed-up on the micro added by JDK-8246152)[1], and
>> on related startup tests[2].
>>
>> Thanks!
>>
>> /Claes
>>
>> [1]
>> Before (JDK-8246152):
>> Benchmark Mode Cnt Score Error Units
>> StringConcatFactoryBootstraps.makeConcatWithConstants avgt 10 2764.634 ± 56.244 ns/op
>> StringConcatFactoryBootstraps.makeConcatWithConstants:·gc.alloc.rate.norm avgt 10 4136.187 ± 0.013 B/op
>>
>> After:
>> Benchmark                Mode  Cnt     Score     Error   Units
>> StringConcatFactoryBootstraps.makeConcatWithConstants avgt 10 2299.919 ± 58.003 ns/op
>> StringConcatFactoryBootstraps.makeConcatWithConstants:·gc.alloc.rate.norm avgt 10 3308.145 ± 6.378 B/op
>>
>> [2] http://cr.openjdk.java.net/~redestad/scratch/erase_scf_types.00/ObjStringCombos.java
>>
>> Before (JDK-8246152):
>>      3,485,679,714      instructions              #    1.09  insn per cycle           ( +-  0.90% )
>>        692,247,529      branches                  #  491.822 M/sec          ( +-  0.92% )
>>         28,939,534      branch-misses             #    4.18% of all branches          ( +-  0.90% )
>>
>>        0.291642667 seconds time elapsed          ( +-  0.93% )
>>
>> After:
>>      3,411,619,586      instructions              #    1.09  insn per cycle           ( +-  0.63% )
>>        677,767,258      branches                  #  493.911 M/sec               ( +-  0.64% )
>>         28,337,022      branch-misses             #    4.18% of all branches          ( +-  0.63% )
>>
>>        0.288959534 seconds time elapsed          ( +-  0.86% )
>