Lambda性能改进，Java 8 vs 11 [英] Lambda performance improvement, Java 8 vs 11
本文介绍了Lambda性能改进，Java 8 vs 11的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我在lambda vs方法参考上运行了一些JMH测试，看起来类似于:
I ran some JMH-tests on lambda vs method reference, looking similar to:
IntStream......reduce(Integer::max)
vs.
IntSream.......reduce((i1, i2) -> Integer.max(i1, i2))
我注意到，在Java 8中，方法引用的执行速度比lambda快5倍. 当我在Java 11中运行测试时，这两种方法的执行时间都与Java 8中的方法引用速度差不多.因此，lambda和Java 11中的方法引用之间在性能上没有重大区别.
What I noticed was that the method reference performed about 5 times as fast as compared to the lambda, in Java 8. When i ran the test in Java 11 the execution time of the both approaches were about as fast as the method reference was in Java 8. So no major difference in performance between lambda and method reference in Java 11.
我的问题是:从Java 8到11进行了哪些改进以提高该性能? 我正在使用OpenJDK.
My question is: What improvement(s) have been made from Java 8 to 11 to boost this performance? I'm using OpenJDK.
编辑 我的基准:
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MILLISECONDS)
@State(Scope.Benchmark)
@Fork(value = 1, jvmArgs = {"-XX:CompileThreshold=5000"})
@Warmup(iterations = 2)
public class FindMaxInt {
@Param({"10000", "1000000", "10000000"})
private int n;
private List<Integer> data;
@Setup
public void setup(){
data = createData();
}
@Benchmark
public void streamWithMethodReference(final Blackhole blackhole){
int max = data.stream().mapToInt(Integer::intValue).reduce(Integer.MIN_VALUE, Integer::max);
blackhole.consume(max);
}
@Benchmark
public void streamWithLambda(final Blackhole blackhole){
int max = data.stream().mapToInt(Integer::intValue).reduce(Integer.MIN_VALUE, (i1, i2) -> Integer.max(i1, i2));
blackhole.consume(max);
}
推荐答案
Here is a combination of effects described in this and this answers.
不同的结果由不同的内联树解释.与方法引用相比，Lambda具有更高的间接级别，因此在JIT编译期间，带有lambda的表达式可能会更早达到内联深度限制.默认值为-XX:MaxInlineLevel=9.
Different results are explained by a different inlining tree. Lambda has one more level of indirection comparing to method reference, so during JIT compilation the expression with lambda may reach the inlining depth limit earlier. The default is -XX:MaxInlineLevel=9.
使用-XX:+PrintCompilation -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlining运行基准测试以查看整个内联树.这是我们在JDK 8上获得的东西:
Run the benchmark with -XX:+PrintCompilation -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlining to see the the whole inlining tree. Here is what we get on JDK 8:
1563 560 4 bench.FindMaxInt::streamWithLambda (38 bytes)
@ 3 java.util.stream.IntPipeline::<init> (7 bytes) inline (hot)
@ 3 java.util.stream.AbstractPipeline::<init> (91 bytes) inline (hot)
@ 1 java.util.stream.PipelineHelper::<init> (5 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 51 java.util.stream.StreamOpFlag::combineOpFlags (9 bytes) inline (hot)
@ 2 java.util.stream.StreamOpFlag::getMask (30 bytes) inline (hot)
@ 66 java.util.stream.IntPipeline$StatelessOp::opIsStateful (2 bytes) inline (hot)
@ 4 java.util.Collection::stream (11 bytes) inline (hot)
\-> TypeProfile (5120/5120 counts) = java/util/ArrayList
@ 1 java.util.ArrayList::spliterator (12 bytes) inline (hot)
@ 8 java.util.ArrayList$ArrayListSpliterator::<init> (26 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 7 java.util.stream.StreamSupport::stream (19 bytes) inline (hot)
@ 1 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 11 java.util.stream.StreamOpFlag::fromCharacteristics (37 bytes) inline (hot)
@ 1 java.util.ArrayList$ArrayListSpliterator::characteristics (4 bytes) inline (hot)
\-> TypeProfile (5124/5124 counts) = java/util/ArrayList$ArrayListSpliterator
@ 15 java.util.stream.ReferencePipeline$Head::<init> (8 bytes) inline (hot)
@ 4 java.util.stream.ReferencePipeline::<init> (8 bytes) inline (hot)
@ 4 java.util.stream.AbstractPipeline::<init> (55 bytes) inline (hot)
@ 1 java.util.stream.PipelineHelper::<init> (5 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 9 java.lang.invoke.LambdaForm$MH/883049899::linkToTargetMethod (8 bytes) force inline by annotation
@ 4 java.lang.invoke.LambdaForm$MH/1922154895::identity_L (8 bytes) force inline by annotation
@ 14 java.util.stream.ReferencePipeline::mapToInt (26 bytes) inline (hot)
\-> TypeProfile (5120/5120 counts) = java/util/stream/ReferencePipeline$Head
@ 1 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 22 java.util.stream.ReferencePipeline$4::<init> (20 bytes) inline (hot)
@ 16 java.util.stream.IntPipeline$StatelessOp::<init> (29 bytes) inline (hot)
@ 3 java.util.stream.IntPipeline::<init> (7 bytes) inline (hot)
@ 3 java.util.stream.AbstractPipeline::<init> (91 bytes) inline (hot)
@ 1 java.util.stream.PipelineHelper::<init> (5 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 51 java.util.stream.StreamOpFlag::combineOpFlags (9 bytes) inline (hot)
@ 2 java.util.stream.StreamOpFlag::getMask (30 bytes) inline (hot)
@ 66 java.util.stream.IntPipeline$StatelessOp::opIsStateful (2 bytes) inline (hot)
@ 21 java.lang.invoke.LambdaForm$MH/883049899::linkToTargetMethod (8 bytes) force inline by annotation
@ 4 java.lang.invoke.LambdaForm$MH/1922154895::identity_L (8 bytes) force inline by annotation
@ 26 java.util.stream.IntPipeline::reduce (16 bytes) inline (hot)
\-> TypeProfile (5120/5120 counts) = java/util/stream/ReferencePipeline$4
@ 3 java.util.stream.ReduceOps::makeInt (18 bytes) inline (hot)
@ 1 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 14 java.util.stream.ReduceOps$5::<init> (16 bytes) inline (hot)
@ 12 java.util.stream.ReduceOps$ReduceOp::<init> (10 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 6 java.util.stream.AbstractPipeline::evaluate (94 bytes) inline (hot)
@ 50 java.util.stream.AbstractPipeline::isParallel (8 bytes) inline (hot)
@ 80 java.util.stream.TerminalOp::getOpFlags (2 bytes) inline (hot)
\-> TypeProfile (5130/5130 counts) = java/util/stream/ReduceOps$5
@ 85 java.util.stream.AbstractPipeline::sourceSpliterator (265 bytes) inline (hot)
@ 79 java.util.stream.AbstractPipeline::isParallel (8 bytes) inline (hot)
@ 88 java.util.stream.ReduceOps$ReduceOp::evaluateSequential (18 bytes) inline (hot)
@ 2 java.util.stream.ReduceOps$5::makeSink (5 bytes) inline (hot)
@ 1 java.util.stream.ReduceOps$5::makeSink (16 bytes) inline (hot)
@ 12 java.util.stream.ReduceOps$5ReducingSink::<init> (15 bytes) inline (hot)
@ 11 java.lang.Object::<init> (1 bytes) inline (hot)
@ 6 java.util.stream.AbstractPipeline::wrapAndCopyInto (18 bytes) inline (hot)
@ 3 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 9 java.util.stream.AbstractPipeline::wrapSink (37 bytes) inline (hot)
@ 1 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 23 java.util.stream.ReferencePipeline$4::opWrapSink (10 bytes) inline (hot)
\-> TypeProfile (5081/5081 counts) = java/util/stream/ReferencePipeline$4
@ 6 java.util.stream.ReferencePipeline$4$1::<init> (11 bytes) inline (hot)
@ 7 java.util.stream.Sink$ChainedReference::<init> (16 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 6 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 13 java.util.stream.AbstractPipeline::copyInto (53 bytes) inline (hot)
@ 1 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 9 java.util.stream.AbstractPipeline::getStreamAndOpFlags (5 bytes) accessor
@ 12 java.util.stream.StreamOpFlag::isKnown (19 bytes) inline (hot)
@ 20 java.util.Spliterator::getExactSizeIfKnown (25 bytes) inline (hot)
\-> TypeProfile (5081/5081 counts) = java/util/ArrayList$ArrayListSpliterator
@ 1 java.util.ArrayList$ArrayListSpliterator::characteristics (4 bytes) inline (hot)
@ 19 java.util.ArrayList$ArrayListSpliterator::estimateSize (11 bytes) inline (hot)
@ 1 java.util.ArrayList$ArrayListSpliterator::getFence (48 bytes) inline (hot)
@ 38 java.util.ArrayList::access$000 (5 bytes) accessor
@ 25 java.util.stream.Sink$ChainedReference::begin (11 bytes) inline (hot)
\-> TypeProfile (5081/5081 counts) = java/util/stream/ReferencePipeline$4$1
@ 5 java.util.stream.ReduceOps$5ReducingSink::begin (9 bytes) inline (hot)
\-> TypeProfile (5079/5079 counts) = java/util/stream/ReduceOps$5ReducingSink
@ 32 java.util.ArrayList$ArrayListSpliterator::forEachRemaining (129 bytes) inline (hot)
@ 51 java.util.ArrayList::access$000 (5 bytes) accessor
@ 99 java.util.stream.ReferencePipeline$4$1::accept (23 bytes) inline (hot)
@ 12 bench.FindMaxInt$$Lambda$8/390011259::applyAsInt (8 bytes) inline (hot)
\-> TypeProfile (13752/13752 counts) = bench/FindMaxInt$$Lambda$8
@ 4 java.lang.Integer::intValue (5 bytes) accessor
@ 17 java.util.stream.ReduceOps$5ReducingSink::accept (19 bytes) inline (hot)
\-> TypeProfile (13752/13752 counts) = java/util/stream/ReduceOps$5ReducingSink
@ 10 bench.FindMaxInt$$Lambda$9/208515840::applyAsInt (6 bytes) inline (hot)
\-> TypeProfile (9107/9107 counts) = bench/FindMaxInt$$Lambda$9
@ 2 bench.FindMaxInt::lambda$streamWithLambda$0 (6 bytes) inline (hot)
@ 2 java.lang.Integer::max (6 bytes) inlining too deep
@ 38 java.util.stream.Sink$ChainedReference::end (10 bytes) inline (hot)
@ 4 java.util.stream.Sink::end (1 bytes) inline (hot)
\-> TypeProfile (5125/5125 counts) = java/util/stream/ReduceOps$5ReducingSink
@ 12 java.util.stream.ReduceOps$5ReducingSink::get (5 bytes) inline (hot)
@ 1 java.util.stream.ReduceOps$5ReducingSink::get (8 bytes) inline (hot)
@ 4 java.lang.Integer::valueOf (32 bytes) inline (hot)
@ 28 java.lang.Integer::<init> (10 bytes) inline (hot)
@ 1 java.lang.Number::<init> (5 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 12 java.lang.Integer::intValue (5 bytes) accessor
@ 34 org.openjdk.jmh.infra.Blackhole::consume (28 bytes) disallowed by CompilerOracle
关键行如下.它们表示内联恰好在最后一次调用Integer.max时中断，因为达到了默认限制9个级别.
The key lines are the following. They mean the inlining breaks exactly at the final call to Integer.max, because the default limit of 9 levels is reached.
@ 2 bench.FindMaxInt::lambda$streamWithLambda$0 (6 bytes) inline (hot)
@ 2 java.lang.Integer::max (6 bytes) inlining too deep
内联树的形状在JDK 11上非常不同:
The shape of the inlining tree is very different on JDK 11:
1588 705 4 bench.FindMaxInt::streamWithLambda (38 bytes)
@ 4 java.util.Collection::stream (11 bytes) inline (hot)
\-> TypeProfile (5263/5263 counts) = java/util/ArrayList
@ 1 java.util.ArrayList::spliterator (12 bytes) inline (hot)
@ 8 java.util.ArrayList$ArrayListSpliterator::<init> (26 bytes) inline (hot)
@ 6 java.lang.Object::<init> (1 bytes) inline (hot)
@ 7 java.util.stream.StreamSupport::stream (19 bytes) inline (hot)
@ 1 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 11 java.util.stream.StreamOpFlag::fromCharacteristics (37 bytes) inline (hot)
@ 1 java.util.ArrayList$ArrayListSpliterator::characteristics (4 bytes) inline (hot)
\-> TypeProfile (5125/5125 counts) = java/util/ArrayList$ArrayListSpliterator
@ 15 java.util.stream.ReferencePipeline$Head::<init> (8 bytes) inline (hot)
@ 4 java.util.stream.ReferencePipeline::<init> (8 bytes) inline (hot)
@ 4 java.util.stream.AbstractPipeline::<init> (55 bytes) inline (hot)
@ 1 java.util.stream.PipelineHelper::<init> (5 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 9 java.lang.invoke.Invokers$Holder::linkToTargetMethod (8 bytes) force inline by annotation
@ 4 java.lang.invoke.LambdaForm$MH/0x0000000800060440::invoke (8 bytes) force inline by annotation
@ 14 java.util.stream.ReferencePipeline::mapToInt (26 bytes) inline (hot)
\-> TypeProfile (5263/5263 counts) = java/util/stream/ReferencePipeline$Head
@ 1 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 22 java.util.stream.ReferencePipeline$4::<init> (20 bytes) inline (hot)
@ 16 java.util.stream.IntPipeline$StatelessOp::<init> (29 bytes) inline (hot)
@ 3 java.util.stream.IntPipeline::<init> (7 bytes) inline (hot)
@ 3 java.util.stream.AbstractPipeline::<init> (91 bytes) inline (hot)
@ 1 java.util.stream.PipelineHelper::<init> (5 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 51 java.util.stream.StreamOpFlag::combineOpFlags (9 bytes) inline (hot)
@ 2 java.util.stream.StreamOpFlag::getMask (30 bytes) inline (hot)
@ 66 java.util.stream.IntPipeline$StatelessOp::opIsStateful (2 bytes) inline (hot)
@ 21 java.lang.invoke.Invokers$Holder::linkToTargetMethod (8 bytes) force inline by annotation
@ 4 java.lang.invoke.LambdaForm$MH/0x0000000800060440::invoke (8 bytes) force inline by annotation
@ 26 java.util.stream.IntPipeline::reduce (16 bytes) inline (hot)
\-> TypeProfile (5263/5263 counts) = java/util/stream/ReferencePipeline$4
@ 3 java.util.stream.ReduceOps::makeInt (18 bytes) inline (hot)
@ 1 java.util.Objects::requireNonNull (14 bytes) inline (hot)
@ 14 java.util.stream.ReduceOps$6::<init> (16 bytes) inline (hot)
@ 12 java.util.stream.ReduceOps$ReduceOp::<init> (10 bytes) inline (hot)
@ 1 java.lang.Object::<init> (1 bytes) inline (hot)
@ 6 java.util.stream.AbstractPipeline::evaluate (94 bytes) inline (hot)
@ 50 java.util.stream.AbstractPipeline::isParallel (8 bytes) inline (hot)
@ 80 java.util.stream.TerminalOp::getOpFlags (2 bytes) inline (hot)
\-> TypeProfile (5362/5362 counts) = java/util/stream/ReduceOps$6
@ 85 java.util.stream.AbstractPipeline::sourceSpliterator (265 bytes) inline (hot)
@ 79 java.util.stream.AbstractPipeline::isParallel (8 bytes) inline (hot)
@ 88 java.util.stream.ReduceOps$ReduceOp::evaluateSequential (18 bytes) already compiled into a big method
@ 12 java.lang.Integer::intValue (5 bytes) accessor
@ 34 org.openjdk.jmh.infra.Blackhole::consume (28 bytes) disallowed by CompileCommand
由于其他原因，编译树更早地关闭了:
The compilation tree cuts off much earlier due to a different reason:
@ 88 java.util.stream.ReduceOps$ReduceOp::evaluateSequential (18 bytes) already compiled into a big method
在JDK 11中默认垃圾回收器已更改为G1.由于G1壁垒，编译后的代码显得更大，这就是为什么内联启发式方法阻止最热的forEachRemaining循环内联到streamWithLambda方法中的原因.
The default garbage collector has changed to G1 in JDK 11. The compiled code appears larger due to G1 barriers, that's why the inlining heuristics prevented the hottest forEachRemaining loop from inlining into the streamWithLambda method.
实际上，这不是JDK 11中的优化，而更像是反过来.但是，该特定基准的整体性能似乎更好，因为内联树剪切发生在最热的循环之外.
In fact, this is not an optimization in JDK 11, but more like the other way round. However, the overall performance of this particular benchmark appeared better, since the inlining tree cutoff happened outside the hottest loop.
这篇关于Lambda性能改进，Java 8 vs 11的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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