prydin

package listener

import (
	"encoding/hex"
	"github.com/twmb/murmur3"
	"unsafe"
)

func CalcTagDigest(metricName, source string, tags map[string]string) string {
	a1, a2 := hashPair("metric", metricName)

prydin

2019-11-01 09:09:29
Full thread dump Java HotSpot(TM) 64-Bit Server VM (10.0.1+10 mixed mode):

Threads class SMR info:
_java_thread_list=0x00007f9e1f019600, length=147, elements={
0x00007f9e1d807800, 0x00007f9e1d81f000, 0x00007f9e1e019800, 0x00007f9e20838800,
0x00007f9e1d823000, 0x00007f9e1e01a000, 0x00007f9e1e004000, 0x00007f9e1f807000,
0x00007f9e1f88d800, 0x00007f9e20805800, 0x00007f9e218e1800, 0x00007f9e2086b000,
0x00007f9e21113000, 0x00007f9e21906800, 0x00007f9e20dfd800, 0x00007f9e1e7f6000,
0x00007f9e1e7f7000, 0x00007f9e200b5800, 0x00007f9e1dd30800, 0x00007f9e21229800,

prydin

public class Test {
    public static void main(String[] args) {
        int value = 0;
        long now = System.currentTimeMillis();
        for(int i = 0; i < 1e8; i++) {
            value++;
        }
        System.out.println("Unsynched version took " + (System.currentTimeMillis() - now) + "ms");
        Object syncher = new Object();
        now = System.currentTimeMillis();

prydin

import java.util.HashMap;

public class HashTest {
    public static void main(String[] args) {
        HashMap<String, String> map = new HashMap<>();
        map.put("foo", "bar");
        long now = System.currentTimeMillis();
        for(int i = 0; i < 1e7; i++) {
            map.get("foo");
        }

prydin

class DoubleCheck {
  private SomeResource myResource;

  public SomeResource getResource() {
    if(myResource != null) {
      return myResource
    }
    synchronized(this) {
      if(myResource != null) {
        return myResource

prydin

class BrokenDontUse {
  private Map<String, SomeResource> aHashMap = new HashMap<>();

  public SomeResource getResource(String name) {
    SomeResource r = aHashMap.get(name);
    if(r != null) {
      return r;
    }
    synchronized(aHashMap) {
      SomeResource r = aHashMap.get(name);

prydin

int waiters = 0; 
void acquireLock() { 
  if(atomicIncrement(waiters) == 0) { 
    rerurn; 
  } 
  callSlowAndPainfulLockingLogic();
}

prydin

class QuestionableUseOfDoubleCheck {
    private long firstAccess = -1;

    public long accessSomething() {
        if (firstAccess != -1) {
            return this.firstAccess;
        }
        synchronized (this) {
            if (this.firstAccess != -1) {
                return this.firstAccess;

prydin

package main

import (
	"fmt"
	"image"
	"image/color"
	"image/png"
	"math"
	"math/cmplx"
	"os"

prydin

package main

import (
	"fmt"
	"image"
	"image/color"
	"image/png"
	"math"
	"math/cmplx"
	"os"