nitsanw

package safepoint.profiling;

import java.util.Random;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;
import java.util.zip.Adler32;
import java.util.zip.CRC32;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;

nitsanw

public class SafepointProfiling {
  @Param("1000")
  int size;
  byte[] buffer;
  byte[] dst;
  boolean result;

  @Setup
  public final void setup() {
    buffer = new byte[size];

nitsanw

enum {
ticks_no_Java_frame         =  0, // new thread
ticks_no_class_load         = -1, // jmethodIds are not available
ticks_GC_active             = -2, // GC action
ticks_unknown_not_Java      = -3, // ¯\_(ツ)_/¯
ticks_not_walkable_not_Java = -4, // ¯\_(ツ)_/¯
ticks_unknown_Java          = -5, // ¯\_(ツ)_/¯
ticks_not_walkable_Java     = -6, // ¯\_(ツ)_/¯
ticks_unknown_state         = -7, // ¯\_(ツ)_/¯
ticks_thread_exit           = -8, // dying thread

nitsanw

typedef struct {
  jint lineno;         // BCI in the source file
  jmethodID method_id; // method executed in this frame
} ASGCT_CallFrame;

typedef struct {
  JNIEnv *env_id   //Env where trace was recorded
  jint num_frames; // number of frames in this trace
  ASGCT_CallFrame *frames;
} ASGCT_CallTrace; 

nitsanw

/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

nitsanw

/*
 * Copyright 2015 dorkbox, llc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software

nitsanw

public static void main(String[] args) throws InterruptedException {
    SampleLinkedQueue<Integer> q = new SampleLinkedQueue<>();
    q.offer(1);
    System.gc(); // N0, N1 are promoted
    Thread.sleep(100);
    q.poll(); // queue is empty, N0 is dead, N1 is alive

    while(true) {
        for (int i = 0; i < 4096; i++) {
          // queue size is kept at 0, but new nodes are created

nitsanw

public class SampleLinkedQueue<E> {
    static class Node<E> {
        Node next;
        E value;
    }

    Node<E> head;
    Node<E> tail;
    SampleLinkedQueue(){
        head = tail = new Node<E>();

nitsanw

  @Benchmark
  @CompilerControl(CompilerControl.Mode.DONT_INLINE)
  public void blameSetResultDeeper() {
    byte b = 0;
    for (int i = 0; i < size; i++) {
      b += buffer[i];
    }
    setResult8(b);
  }

nitsanw

  @Benchmark
  public void blameSetResult() {
    byte b = 0;
    for (int i = 0; i < size; i++) {
      b += buffer[i];
    }
    setResult(b); /* LINE 38 */
  }

  private void setResult(byte b) {