测试特性
- 最大线程数量为n，有界队列为m,当向线程池提交n+m个任务时，线程池中的线程池大小为n
环境
- jdk 1.8
- maven
<!-- junit test -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
测试
测试用例
package concurrent;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import util.StdOut;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
/**
* ThreadPoolExecutor测试类
*/
public class ThreadPoolExecutorTest {
/**
* 线程池中线程索引
*/
private final AtomicInteger pooledThreadIdx = new AtomicInteger(0);
/**
* 核心线程数
*/
private final int coreSizeN = 1;
/**
* 最大线程数
*/
private final int maxSizeN = 3;
/**
* 任务最大排队数量
*/
private final int queueSizeM = 10;
/**
* 线程池中大于coreSize的线程空闲时间，单位：毫秒
*/
private final long keepAliveTime = 60L * 1000;
/**
* 线程池
*/
private ThreadPoolExecutor threadPoolExecutor;
/**
* 控制线程池任务执行开关
*/
private final AtomicBoolean pass = new AtomicBoolean(false);
@Before
public void before() {
// 新建线程池
threadPoolExecutor = new ThreadPoolExecutor(
coreSizeN,
maxSizeN,
keepAliveTime,
TimeUnit.MILLISECONDS,
// 任务队列为最大排队为10的任务队列
new ArrayBlockingQueue<>(queueSizeM),
// 定制ThreadFactory，定义线程名称，以在多个线程池场景下区分业务线程
r -> new Thread(r, "executor-tester-" + pooledThreadIdx.getAndIncrement()),
// 如果排队数量超过10，且线程最大已经达到maximumPoolSize时，再有任务提交时的拒绝策略
// 一般是直接拒绝：表示服务仅能支撑这么多
new ThreadPoolExecutor.AbortPolicy()
);
}
/**
* 测试线程池线程数量等于最大线程数用例
* @throws InterruptedException
*/
@Test
public void testThreadCountGreaterThanCoreSize() throws InterruptedException {
// 向线程池提交n + m个任务
submitTask(threadPoolExecutor, pass, maxSizeN + queueSizeM);
startControlThread(pass, maxSizeN, threadPoolExecutor);
}
/**
* 提交任务到线程池
* @param threadPoolExecutor 线程池
* @param pass 任务控制开关
* @param taskCount 任务数量
*/
private void submitTask(ThreadPoolExecutor threadPoolExecutor, AtomicBoolean pass, int taskCount) {
for (int i = 0; i < taskCount; i++) {
threadPoolExecutor.submit(() -> {
while (!pass.get()) {
StdOut.println(Thread.currentThread().getName() + ": Thread running..." );
sleep(1000);
}
});
}
}
/**
* 睡眠
* @param millis 睡眠时间，单位：毫秒
*/
public static void sleep(long millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 控制线程池中任务执行的线程
* @param pass 任务执行开关 true:任务执行，false：任务睡眠
* @param maxSizeN 线程池中最大线程数量
* @param threadPoolExecutor 线程池
* @throws InterruptedException
*/
private void startControlThread(AtomicBoolean pass, int maxSizeN, ThreadPoolExecutor threadPoolExecutor) throws InterruptedException {
// 控制线程
Thread controlThread = new Thread(() -> {
int i = 0;
while (i++ < 10) {
// 先将自己睡眠一秒防止线程池还没有“反应过来”就获取活动线程数量为0的问题
sleep(1000);
// 睡眠一秒后再获取活动的线程数量应该为1,
Assert.assertEquals(maxSizeN, threadPoolExecutor.getActiveCount());
StdOut.println("thread pool running workers: " + threadPoolExecutor.getActiveCount());
}
// 将线程中的任务全部放行
pass.set(true);
i = 0;
// 等待大约2秒时间再判断线程池中的活动线程数量应该为0
// 因为任务已经执行完成了
while (i++ < 10) {
sleep(200);
StdOut.println("thread pool running workers: " + threadPoolExecutor.getActiveCount());
}
Assert.assertEquals(0, threadPoolExecutor.getActiveCount());
StdOut.println("thread pool running workers: " + threadPoolExecutor.getActiveCount());
});
controlThread.start();
controlThread.join();
}
}
Console输出
executor-tester-0: Thread running...
executor-tester-1: Thread running...
executor-tester-2: Thread running...
executor-tester-2: Thread running...
executor-tester-1: Thread running...
executor-tester-0: Thread running...
thread pool running workers: 3
executor-tester-0: Thread running...
thread pool running workers: 3
executor-tester-2: Thread running...
executor-tester-1: Thread running...
executor-tester-2: Thread running...
executor-tester-1: Thread running...
executor-tester-0: Thread running...
thread pool running workers: 3
executor-tester-2: Thread running...
thread pool running workers: 3
executor-tester-1: Thread running...
executor-tester-0: Thread running...
executor-tester-2: Thread running...
executor-tester-1: Thread running...
executor-tester-0: Thread running...
thread pool running workers: 3
executor-tester-0: Thread running...
thread pool running workers: 3
executor-tester-1: Thread running...
executor-tester-2: Thread running...
executor-tester-2: Thread running...
thread pool running workers: 3
executor-tester-0: Thread running...
executor-tester-1: Thread running...
executor-tester-2: Thread running...
executor-tester-1: Thread running...
executor-tester-0: Thread running...
thread pool running workers: 3
executor-tester-0: Thread running...
executor-tester-1: Thread running...
thread pool running workers: 3
executor-tester-2: Thread running...
executor-tester-1: Thread running...
executor-tester-0: Thread running...
executor-tester-2: Thread running...
thread pool running workers: 3
thread pool running workers: 3
thread pool running workers: 3
thread pool running workers: 3
thread pool running workers: 3
thread pool running workers: 0
thread pool running workers: 0
thread pool running workers: 0
thread pool running workers: 0
thread pool running workers: 0
thread pool running workers: 0
thread pool running workers: 0
