jmh

问题 In my scenario, the methods in benchmark should run sequentially in one thread and modify the state in order. For example, there is a List<Integer> called num in the benchmark class. What I want is: first, run add() to append a number into the list. Then, run remove() to remove the number from the list. The calling sequence must be add() --> remove() . If remove() runs before add() or they run concurrently, they would raise exceptions because there's no element in the list. That is, add() and

问题 I'm trying to measure the memory consumed when running the benchmark. I found out on the internet that I can use GC profiler to measure that. I tried but I don't understand the answer as well as see the amount of consumed memory. Can anyone explain the results? Thanks. MyBenchmark.testMethod_width_2_attribute_text ss 60 32.345 ± 1.759 ms/op MyBenchmark.testMethod_width_2_attribute_text:·gc.alloc.rate ss 60 26.904 ± 0.217 MB/sec MyBenchmark.testMethod_width_2_attribute_text:·gc.alloc.rate.norm

问题 I'm trying to measure the memory consumed when running the benchmark. I found out on the internet that I can use GC profiler to measure that. I tried but I don't understand the answer as well as see the amount of consumed memory. Can anyone explain the results? Thanks. MyBenchmark.testMethod_width_2_attribute_text ss 60 32.345 ± 1.759 ms/op MyBenchmark.testMethod_width_2_attribute_text:·gc.alloc.rate ss 60 26.904 ± 0.217 MB/sec MyBenchmark.testMethod_width_2_attribute_text:·gc.alloc.rate.norm

问题 I'm trying to measure the memory consumed when running the benchmark. I found out on the internet that I can use GC profiler to measure that. I tried but I don't understand the answer as well as see the amount of consumed memory. Can anyone explain the results? Thanks. MyBenchmark.testMethod_width_2_attribute_text ss 60 32.345 ± 1.759 ms/op MyBenchmark.testMethod_width_2_attribute_text:·gc.alloc.rate ss 60 26.904 ± 0.217 MB/sec MyBenchmark.testMethod_width_2_attribute_text:·gc.alloc.rate.norm

问题 I wrote a JMH test about the cost of new instruction, and checked the class files it generates. Except the usual classes, there're tons of derived classes in generated folder: This really shocked me, for just few annotations will lead to so many class bounded together through inheritance. I am curious about what things are in those class, so I use a decompile tool (BTW I learned this tool from one talk on KotlinConf 2019) called procyon to decompile these generated class, most of them are

问题 I have written some Scala code to perform an element-wise operation on a collection. Here I defined two methods that perform the same task. One method uses zip and the other uses zipped . def ES (arr :Array[Double], arr1 :Array[Double]) :Array[Double] = arr.zip(arr1).map(x => x._1 + x._2) def ES1(arr :Array[Double], arr1 :Array[Double]) :Array[Double] = (arr,arr1).zipped.map((x,y) => x + y) To compare these two methods in terms of speed, I wrote the following code: def fun (arr : Array[Double

问题 I've set up a JMH benchmark to measure what would be faster Arrays.fill with null, System.arraycopy from a null array, zeroying a DirectByteBuffer or zeroying an unsafe memory block trying to answer this question Let's put aside that zeroying a directly allocated memory is a rare case, and discuss the results of my benchmark. Here's the JMH benchmark snippet (full code available via a gist) including unsafe.setMemory case as suggested by @apangin in the original post, byteBuffer.put(byte[],

问题 I have: Methods like this: @GenerateMicroBenchmark public static void calculateArraySummary(String[] args) { // create a random data set /* PROBLEM HERE: * now I measure not only pool.invoke(finder) time, * but also generateRandomArray method time */ final int[] array = generateRandomArray(1000000); // submit the task to the pool final ForkJoinPool pool = new ForkJoinPool(4); final ArraySummator finder = new ArraySummator(array); System.out.println(pool.invoke(finder)); } private static int[]

问题 I have a several heavy benchmark classes annotated with @Benchmark. After bulding jar with benchmarks I can run all of them with following command java -Xmx4G -jar benchmarks.jar -f 1 -wi 3 -i 10 How to specify benchmarks to run, if I don't want to run all of them? 回答1: When in doubt, ask for command line help. In fact, running the JAR with -h yields: Usage: java -jar ... [regexp*] [options] [opt] means optional argument. <opt> means required argument. "+" means comma-separated list of values

问题 I have some JMH benchmarks that I'm trying to analyze. I want to enable GC logging to see how much garbage is being generated, but I can't figure out how to pass JVM arguments. I know JMH runs benchmarks in a forked JVM, so it's not immediately obvious to me how to do this. I'm using SBT. 回答1: If I read sbt-jmh docs right, it passes the application options to JMH runner with jmh:run ... . So, having that JMH command line accepts --jvmArgs "..." , I would try to do jmh:run --jvmArgs "-XX: