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Optimize leastActiveSelect and weight test case #2172

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Sep 27, 2018
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,6 @@
*/
package org.apache.dubbo.rpc.cluster.loadbalance;

import org.apache.dubbo.common.Constants;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.rpc.Invocation;
import org.apache.dubbo.rpc.Invoker;
Expand All @@ -27,7 +26,6 @@

/**
* LeastActiveLoadBalance
*
*/
public class LeastActiveLoadBalance extends AbstractLoadBalance {

Expand All @@ -39,26 +37,26 @@ protected <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation
int leastActive = -1; // The least active value of all invokers
int leastCount = 0; // The number of invokers having the same least active value (leastActive)
int[] leastIndexes = new int[length]; // The index of invokers having the same least active value (leastActive)
int totalWeight = 0; // The sum of weights
int totalWeight = 0; // The sum of with warmup weights
int firstWeight = 0; // Initial value, used for comparision
boolean sameWeight = true; // Every invoker has the same weight value?
for (int i = 0; i < length; i++) {
Invoker<T> invoker = invokers.get(i);
int active = RpcStatus.getStatus(invoker.getUrl(), invocation.getMethodName()).getActive(); // Active number
int weight = invoker.getUrl().getMethodParameter(invocation.getMethodName(), Constants.WEIGHT_KEY, Constants.DEFAULT_WEIGHT); // Weight
int afterWarmup = getWeight(invoker, invocation);
if (leastActive == -1 || active < leastActive) { // Restart, when find a invoker having smaller least active value.
leastActive = active; // Record the current least active value
leastCount = 1; // Reset leastCount, count again based on current leastCount
leastIndexes[0] = i; // Reset
totalWeight = weight; // Reset
firstWeight = weight; // Record the weight the first invoker
totalWeight = afterWarmup; // Reset
firstWeight = afterWarmup; // Record the weight the first invoker
sameWeight = true; // Reset, every invoker has the same weight value?
} else if (active == leastActive) { // If current invoker's active value equals with leaseActive, then accumulating.
leastIndexes[leastCount++] = i; // Record index number of this invoker
totalWeight += weight; // Add this invoker's weight to totalWeight.
totalWeight += afterWarmup; // Add this invoker's with warmup weight to totalWeight.
// If every invoker has the same weight?
if (sameWeight && i > 0
&& weight != firstWeight) {
&& afterWarmup != firstWeight) {
sameWeight = false;
}
}
Expand All @@ -70,7 +68,7 @@ protected <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation
}
if (!sameWeight && totalWeight > 0) {
// If (not every invoker has the same weight & at least one invoker's weight>0), select randomly based on totalWeight.
int offsetWeight = ThreadLocalRandom.current().nextInt(totalWeight);
int offsetWeight = ThreadLocalRandom.current().nextInt(totalWeight) + 1;
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Why change ThreadLocalRandom.current().nextInt(totalWeight) to ThreadLocalRandom.current().nextInt(totalWeight) + 1 ?

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Is it possible that +1 causes offset not equal or less 0?

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If not change to +1, that will cause a bug.
U can look at my unit test for more detail.

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@code4wt code4wt Nov 27, 2018

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最近正好在看 LeastActiveLoadBalance 的源码,我觉得 +1 这个逻辑有点突兀,不知道背景的同学可能不知道为什么要+1。更合理的方式,我觉得应该按照 RandomLoadBalance 逻辑去处理。将 if (offsetWeight <= 0) 改为 if (offsetWeight < 0),这样两者的逻辑能够统一起来。只要大家能看懂 RandomLoadBalance 的代码 ,那么此处的代码也一样能看懂,而不用特地去思考为什么要 +1。你觉得呢

// Return a invoker based on the random value.
for (int i = 0; i < leastCount; i++) {
int leastIndex = leastIndexes[i];
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,6 @@
package org.apache.dubbo.rpc.cluster.loadbalance;

import org.apache.dubbo.rpc.Invoker;

import org.junit.Assert;
import org.junit.Ignore;
import org.junit.Test;
Expand All @@ -39,4 +38,31 @@ public void testLeastActiveLoadBalance_select() {
}
}

@Test
public void testSelectByWeight() {
int sumInvoker1 = 0;
int sumInvoker2 = 0;
int loop = 10000;

LeastActiveLoadBalance lb = new LeastActiveLoadBalance();
for (int i = 0; i < loop; i++) {
Invoker selected = lb.select(weightInvokers, null, weightTestInvocation);

if (selected.getUrl().getProtocol().equals("test1")) {
sumInvoker1++;
}

if (selected.getUrl().getProtocol().equals("test2")) {
sumInvoker2++;
}
// never select invoker3 because it's active is more than invoker1 and invoker2
Assert.assertTrue("select is not the least active one", !selected.getUrl().getProtocol().equals("test3"));
}

// the sumInvoker1 : sumInvoker2 approximately equal to 1: 9
System.out.println(sumInvoker1);
System.out.println(sumInvoker2);

Assert.assertEquals("select failed!", sumInvoker1 + sumInvoker2, loop);
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,9 @@
import org.apache.dubbo.common.extension.ExtensionLoader;
import org.apache.dubbo.rpc.Invocation;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.RpcInvocation;
import org.apache.dubbo.rpc.RpcStatus;
import org.apache.dubbo.rpc.cluster.LoadBalance;

import org.junit.Assert;
import org.junit.Before;
import org.junit.BeforeClass;
Expand Down Expand Up @@ -50,6 +51,12 @@ public class LoadBalanceBaseTest {
Invoker<LoadBalanceBaseTest> invoker4;
Invoker<LoadBalanceBaseTest> invoker5;

RpcStatus weightTestRpcStatus1;
RpcStatus weightTestRpcStatus2;
RpcStatus weightTestRpcStatus3;

RpcInvocation weightTestInvocation;

/**
* @throws java.lang.Exception
*/
Expand Down Expand Up @@ -145,4 +152,55 @@ private static int calculateDefaultWarmupWeight(int uptime) {
return AbstractLoadBalance.calculateWarmupWeight(uptime, Constants.DEFAULT_WARMUP, Constants.DEFAULT_WEIGHT);
}

/*------------------------------------test invokers for weight---------------------------------------*/

protected List<Invoker<LoadBalanceBaseTest>> weightInvokers = new ArrayList<Invoker<LoadBalanceBaseTest>>();
protected Invoker<LoadBalanceBaseTest> weightInvoker1;
protected Invoker<LoadBalanceBaseTest> weightInvoker2;
protected Invoker<LoadBalanceBaseTest> weightInvoker3;

@Before
public void before() throws Exception {
weightInvoker1 = mock(Invoker.class);
weightInvoker2 = mock(Invoker.class);
weightInvoker3 = mock(Invoker.class);

weightTestInvocation = new RpcInvocation();
weightTestInvocation.setMethodName("test");

URL url1 = URL.valueOf("test1://0:1/DemoService");
url1 = url1.addParameter(Constants.WEIGHT_KEY, 1);
url1 = url1.addParameter(weightTestInvocation.getMethodName() + "." + Constants.WEIGHT_KEY, 1);
url1 = url1.addParameter("active", 0);

URL url2 = URL.valueOf("test2://0:9/DemoService");
url2 = url2.addParameter(Constants.WEIGHT_KEY, 9);
url2 = url2.addParameter(weightTestInvocation.getMethodName() + "." + Constants.WEIGHT_KEY, 9);
url2 = url2.addParameter("active", 0);

URL url3 = URL.valueOf("test3://1:6/DemoService");
url3 = url3.addParameter(Constants.WEIGHT_KEY, 6);
url3 = url3.addParameter(weightTestInvocation.getMethodName() + "." + Constants.WEIGHT_KEY, 6);
url3 = url3.addParameter("active", 1);

given(weightInvoker1.isAvailable()).willReturn(true);
given(weightInvoker1.getUrl()).willReturn(url1);

given(weightInvoker2.isAvailable()).willReturn(true);
given(weightInvoker2.getUrl()).willReturn(url2);

given(weightInvoker3.isAvailable()).willReturn(true);
given(weightInvoker3.getUrl()).willReturn(url3);

weightInvokers.add(weightInvoker1);
weightInvokers.add(weightInvoker2);
weightInvokers.add(weightInvoker3);

weightTestRpcStatus1 = RpcStatus.getStatus(weightInvoker1.getUrl(), weightTestInvocation.getMethodName());
weightTestRpcStatus2 = RpcStatus.getStatus(weightInvoker2.getUrl(), weightTestInvocation.getMethodName());
weightTestRpcStatus3 = RpcStatus.getStatus(weightInvoker3.getUrl(), weightTestInvocation.getMethodName());

// weightTestRpcStatus3 active is 1
RpcStatus.beginCount(weightInvoker3.getUrl(), weightTestInvocation.getMethodName());
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@

import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.RpcStatus;

import org.junit.Assert;
import org.junit.Test;

Expand Down Expand Up @@ -54,4 +53,35 @@ public void testRandomLoadBalanceSelect() {
Assert.assertEquals(0, counter.get(invoker5).intValue());
}

@Test
public void testSelectByWeight() {
int sumInvoker1 = 0;
int sumInvoker2 = 0;
int sumInvoker3 = 0;
int loop = 10000;

RandomLoadBalance lb = new RandomLoadBalance();
for (int i = 0; i < loop; i++) {
Invoker selected = lb.select(weightInvokers, null, weightTestInvocation);

if (selected.getUrl().getProtocol().equals("test1")) {
sumInvoker1++;
}

if (selected.getUrl().getProtocol().equals("test2")) {
sumInvoker2++;
}

if (selected.getUrl().getProtocol().equals("test3")) {
sumInvoker3++;
}
}

// 1 : 9 : 6
System.out.println(sumInvoker1);
System.out.println(sumInvoker2);
System.out.println(sumInvoker3);
Assert.assertEquals("select failed!", sumInvoker1 + sumInvoker2 + sumInvoker3, loop);
}

}
Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,6 @@
package org.apache.dubbo.rpc.cluster.loadbalance;

import org.apache.dubbo.rpc.Invoker;

import org.junit.Assert;
import org.junit.Test;

Expand All @@ -34,4 +33,36 @@ public void testRoundRobinLoadBalanceSelect() {
Assert.assertTrue("abs diff should < 1", Math.abs(count - runs / (0f + invokers.size())) < 1f);
}
}

@Test
public void testSelectByWeight() {
int sumInvoker1 = 0;
int sumInvoker2 = 0;
int sumInvoker3 = 0;
int loop = 10000;

RoundRobinLoadBalance lb = new RoundRobinLoadBalance();
for (int i = 0; i < loop; i++) {
Invoker selected = lb.select(weightInvokers, null, weightTestInvocation);

if (selected.getUrl().getProtocol().equals("test1")) {
sumInvoker1++;
}

if (selected.getUrl().getProtocol().equals("test2")) {
sumInvoker2++;
}

if (selected.getUrl().getProtocol().equals("test3")) {
sumInvoker3++;
}
}

// 1 : 9 : 6
System.out.println(sumInvoker1);
System.out.println(sumInvoker2);
System.out.println(sumInvoker3);
Assert.assertEquals("select failed!", sumInvoker1 + sumInvoker2 + sumInvoker3, loop);
}

}