文章目錄

• 背景
• 多線(xiàn)程場(chǎng)景測(cè)試代碼
• 結(jié)論

背景

ThreadLocal原理以及基本概念這里我就不介紹了，這里我們主要關(guān)注ThreadLocal是否是線(xiàn)程安全嗎？其實(shí)如果我們知道ThreadLocal原理我們肯定知道它是線(xiàn)程安全的，但是我在開(kāi)發(fā)的時(shí)候不放心做了個(gè)測(cè)試，也順便把測(cè)試demo貼一下

多線(xiàn)程場(chǎng)景測(cè)試代碼

多線(xiàn)程測(cè)試代碼：

package net.dreamzuora.utils;import java.util.UUID; import java.util.concurrent.*;public class ThreadLocalMultiThread {ThreadLocal<String> threadLocal = new ThreadLocal<>();public static void main(String[] args) throws InterruptedException {CountDownLatch countDownLatch = new CountDownLatch(1);ThreadPoolExecutor.CallerRunsPolicy callerRunsPolicy = new ThreadPoolExecutor.CallerRunsPolicy();ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10, 3, TimeUnit.SECONDS, new ArrayBlockingQueue<>(200), new MyThreadFactory(), callerRunsPolicy);ThreadLocalMultiThread threadLocalMultiThread = new ThreadLocalMultiThread();for (int k =0; k < 500; k++){threadPoolExecutor.execute(threadLocalMultiThread.new TestWorker());}countDownLatch.await();}class TestWorker implements Runnable{@Overridepublic void run() {try {String s = UUID.randomUUID().toString();System.out.println(System.currentTimeMillis() + " " + Thread.currentThread().getName() + " producer : " + s);threadLocal.set(s);TimeUnit.SECONDS.sleep(1);System.out.println(System.currentTimeMillis() + " " + Thread.currentThread().getName() + "consumer : " + threadLocal.get());threadLocal.remove();} catch (InterruptedException e) {e.printStackTrace();}}}static int i = 0;static class MyThreadFactory implements ThreadFactory{@Overridepublic Thread newThread(Runnable r) {return new Thread(r, "my thread-" + i++);}}}

輸出結(jié)果：

結(jié)論

最終可以發(fā)現(xiàn)在用一個(gè)線(xiàn)程中生產(chǎn)和消費(fèi)他們的UUID始終是一致的，因而可以通過(guò)測(cè)試案例證明他們是線(xiàn)程安全的，可以放心使用啦

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