Classfile API performance and caching in Constant API

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Sure. My patches for new Constant API and caching will not migrate
existing parts using ASM or other libraries to Classfile API, if that
is what you mean.

In addition, I have another patch that provides general improvements
to MethodTypeDesc https://github.com/openjdk/jdk/pull/13186 while
fixing its mutability bug,
and wishes to add two new APIs MethodTypeDesc.of(ClassDesc returnType)
and MethodTypeDesc.of(ClassDesc returnType, Collection<ClassDesc>
parameterTypes) as well.

So, in general, what I want to accomplish in the Constant API is these:
1. Add ClassDesc.internalName() which returns a string suitable for
CONSTANT_Class_info for better performance
2. Add caching to this internalName and MethodTypeDesc.descriptorString()
3. Add MethodTypeDesc.of(ClassDesc returnType) and
MethodTypeDesc.of(ClassDesc returnType, Collection<ClassDesc>
parameterTypes) for convenience
4. Fix the bug that MethodTypeDesc.of(ClassDesc, ClassDesc[]) can be
mutated by input array
5. Move the storage of parameters in MethodTypeDesc from ClassDesc[]
to List<ClassDesc> (using List.of immutable lists) to speed up
parameterList()
6. Optimize MethodTypeDesc.resolveConstantDesc() to resolve from class
descs (parsing raw descriptor strings take longer from my benchmarks)
and reject more-than-255-slot descs more eagerly

Should I submit separate patches, one for each?

Chen

On Fri, Apr 21, 2023 at 11:29 AM Brian Goetz <brian.goetz at oracle.com> wrote:
>
> Can you separate the pure JDK implementation improvements (e.g., making j.u.c more efficient) from the "switch to using classfile API in X" into separate patches?
>
> On 4/21/2023 12:23 PM, - wrote:
>
> If there is no objection, I will submit a patch incorporating the
> caching and internalName method to the Constant API, to make the
> Classfile API more efficient.
>
> Chen
>
> On Wed, Apr 19, 2023 at 11:15 PM - <liangchenblue at gmail.com> wrote:
>
> Hello,
> Since Adam has revealed that Classfile API is somewhat hampered by
> performance issues and added a few patches in
> https://github.com/openjdk/jdk/pull/12945/ that performs caching,
>
> His patch focuses on two optimizations:
> 1. Speed up construction of descriptor string for MethodTypeDesc
> 2. Caching of ClassDesc symbol in ClassEntry (representing CONSTANT_Class_info)
>
> Inspired by and in addition to his patches, I decided to try and see
> the extent of performance impact of repeated string computation and
> allocations from:
> 1. Creation of internal names from ClassDesc
>     I added a temporary API, String internalName(), to ClassDesc. This
> API is forward-compatible with Valhalla, that it returns a String
> suitable for a CONSTANT_Class_info.
> 2. Repeated descriptorString calls on MethodTypeDesc
>     I added a simple caching logic, much like the existing one in
> java.lang.invoke.MethodType.
> In addition, if the internal name and descriptor string are already
> available via factory methods, the cache fields are immediately
> assigned as well.
>
> The results are promising: In jdk.classfile.Write benchmark
> https://github.com/openjdk/jdk/blob/master/test/micro/org/openjdk/bench/jdk/classfile/Write.java,
> The throughput with Classfile API increased by 1/3.
>
> Master (Patch of https://bugs.openjdk.org/browse/JDK-8305669, since
> otherwise cannot run JMH with make on Windows):
> Benchmark                Mode  Cnt      Score     Error  Units
> Write.asmStream         thrpt    5  44866.172 ± 144.049  ops/s
> Write.jdkTree           thrpt    5  16282.041 ±  95.782  ops/s
> Write.jdkTreePrimitive  thrpt    5  16352.972 ± 280.751  ops/s
>
> New (https://github.com/liachmodded/jdk/commit/e33261ad197c33836d56b4b48acabc04880a780b)
> Benchmark                Mode  Cnt      Score     Error  Units
> Write.asmStream         thrpt    5  45695.225 ± 649.249  ops/s
> Write.jdkTree           thrpt    5  22786.872 ± 256.329  ops/s
> Write.jdkTreePrimitive  thrpt    5  22437.085 ± 397.090  ops/s
>
> As a result, I believe it may be worth to update the Constant API to
> offer ClassDesc::internalName() and method type descriptor string
> caching, to enable better performance in the Classfile API.
>
> Thanks for reading,
> Chen Liang
>
>