{"id":4633,"date":"2020-01-11T21:14:00","date_gmt":"2020-01-11T13:14:00","guid":{"rendered":"https:\/\/www.xttblog.com\/?p=4633"},"modified":"2020-01-12T17:27:05","modified_gmt":"2020-01-12T09:27:05","slug":"volatile%e5%8f%af%e8%a7%81%e6%80%a7%e5%8e%9f%e7%90%86%e6%9c%80%e5%bc%ba%e6%80%bb%e7%bb%93","status":"publish","type":"post","link":"https:\/\/www.xttblog.com\/?p=4633","title":{"rendered":"volatile\u53ef\u89c1\u6027\u539f\u7406\u6700\u5f3a\u603b\u7ed3"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">\u6700\u8fd1\u770b\u5230\u4e00\u7bc7\u5f88\u597d\u7684 volatile \u53ef\u89c1\u6027\u539f\u7406\u603b\u7ed3\uff0c\u5206\u4eab\u7ed9\u5927\u5bb6\uff01<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">volatile \u662f\u4e00\u79cd\u8f7b\u91cf\u4e14\u5728\u6709\u9650\u7684\u6761\u4ef6\u4e0b\u7ebf\u7a0b\u5b89\u5168\u6280\u672f\uff0c\u5b83\u4fdd\u8bc1\u4fee\u9970\u7684\u53d8\u91cf\u7684\u53ef\u89c1\u6027\u548c\u6709\u5e8f\u6027\uff0c\u4f46\u975e\u539f\u5b50\u6027\u3002\u76f8\u5bf9\u4e8e synchronize \u9ad8\u6548\uff0c\u800c\u5e38\u5e38\u8ddf synchronize \u914d\u5408\u4f7f\u7528\u3002<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter\"><img decoding=\"async\" src=\"https:\/\/images.weserv.nl\/?url=https:\/\/wx2.sinaimg.cn\/mw690\/8fa5dcfcgy1gaswg0m17ij21q80fc4qp.jpg\" alt=\"\" \/><figcaption>volatile \u539f\u7406<\/figcaption><\/figure><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">\u5148\u7b80\u5355\u8bf4\u4e00\u4e0b Java \u5185\u5b58\u6a21\u578b\u3002\u8fd9\u91cc\u4e3b\u8981\u63cf\u8ff0\u7684\u7ebf\u7a0b\uff0c\u5de5\u4f5c\u5185\u5b58\uff0c\u4e3b\u5b58\u7684\u53d8\u91cf\u7684\u8bfb\u5199\u5173\u7cfb\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u4e3b\u5b58\u5b58\u653e\u7ebf\u7a0b\u9700\u8981\u64cd\u4f5c\u7684\u53d8\u91cf\uff0c\u4f46\u7ebf\u7a0b\u5e76\u4e0d\u76f4\u63a5\u64cd\u4f5c\u4e3b\u5b58\u3002<\/li><li>\u6bcf\u4e2a\u7ebf\u7a0b\u8bfb\u53d6\u4e3b\u5b58\u53d8\u91cf\u90fd\u662f\u5148\u62f7\u8d1d\u4e00\u4efd\u5230\u5de5\u4f5c\u5185\u5b58\u4e2d\uff0c\u4e0d\u540c\u7ebf\u7a0b\u5de5\u4f5c\u5185\u5b58\u4e92\u4e0d\u5e72\u6270\u3002<\/li><li>\u7ebf\u7a0b\u4fee\u6539\u4e86\u5de5\u4f5c\u5185\u5b58\u540e\uff0c\u518d\u5199\u56de\u4e3b\u5b58\u4e2d\u3002<\/li><li>\u6bcf\u6b21\u4ece\u4e3b\u5b58\u8bfb\u5199\u7684\u8fc7\u7a0b\u90fd\u9700\u8981\u7ecf\u8fc78\u539f\u5b50\u6027\u64cd\u4f5c\u3002<\/li><\/ul>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter\"><img decoding=\"async\" src=\"https:\/\/images.weserv.nl\/?url=https:\/\/wx1.sinaimg.cn\/mw690\/8fa5dcfcgy1gaswg0ccwkj20h50f4wfn.jpg\" alt=\"\" \/><figcaption>volatile \u53ef\u89c1\u6027<\/figcaption><\/figure><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">volatile \u53ef\u89c1\u6027\u7684\u7279\u6b8a\u6027\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>\u64cd\u4f5c use \u4e4b\u524d\u5fc5\u987b\u5148\u6267\u884c read \u548c load \u64cd\u4f5c\u3002<\/li><li>\u64cd\u4f5c assign \u4e4b\u540e\u5fc5\u987b\u6267\u884c store \u548c write \u64cd\u4f5c\u3002<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u7531\u7279\u6027\u6027\u4fdd\u8bc1\u4e86 read\u3001load \u548c use \u7684\u64cd\u4f5c\u8fde\u7eed\u6027\uff0cassign\u3001store \u548c write \u7684\u64cd\u4f5c\u8fde\u7eed\u6027\uff0c\u4ece\u800c\u8fbe\u5230\u5de5\u4f5c\u5185\u5b58\u8bfb\u53d6\u524d\u5fc5\u987b\u5237\u65b0\u4e3b\u5b58\u6700\u65b0\u503c\uff1b\u5de5\u4f5c\u5185\u5b58\u5199\u5165\u540e\u5fc5\u987b\u540c\u6b65\u5230\u4e3b\u5b58\u4e2d\u3002\u8bfb\u53d6\u7684\u8fde\u7eed\u6027\u548c\u5199\u5165\u7684\u8fde\u7eed\u6027\uff0c\u770b\u4e0a\u53bb\u50cf\u7ebf\u7a0b\u76f4\u63a5\u64cd\u4f5c\u4e86\u4e3b\u5b58\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6269\u5c55\uff1alock \u548c unlock \u64cd\u4f5c\u5e76\u4e0d\u76f4\u63a5\u5f00\u653e\u7ed9\u7528\u6237\u4f7f\u7528\uff0c\u800c\u662f\u63d0\u4f9b\u7ed9\u50cf Synchronize \u5173\u952e\u5b57\u6307\u5b9a monitorenter \u548c monitorexit \u9690\u5f0f\u4f7f\u7528\u3002\u5173\u4e8e Synchronize \u7684\u76d1\u542c\u5668\u9501 monitor\uff0cjavac \u7f16\u8bd1\u540e\u4f1a\u5728\u4f5c\u7528\u7684\u65b9\u6cd5\u524d\u540e\u589e\u52a0 monitorenter \u548c monitorexit \u6307\u4ee4\uff0c\u8be6\u7ec6\u7684\u53ef\u4ee5\u67e5\u770b synchronize \u539f\u7406\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0b\u9762\u4f7f\u7528 Java \u4ee3\u7801\u9a8c\u8bc1 volatile \u53ef\u89c1\u6027\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class VolatileVisibility {\n    public static class TestData {\n        volatile int num = 0;\n        public void updateNum(){\n            num = 1;\n        }\n    }\n    public static void main(String[] args) {\n        final TestData testData = new TestData();\n        new Thread(new Runnable() {\n            @Override\n            public void run() {\n                System.out.println(\"ChildThread num--&gt;\"+testData.num);\n                try {\n                    Thread.sleep(1000);\n                } catch (InterruptedException e) {\n                    e.printStackTrace();\n                }\n                testData.updateNum();\n                System.out.println(\"ChildThread update num--&gt;\"+testData.num);\n            }\n        }).start();\n        while (testData.num == 0){}\n        System.out.println(\"MainThread num--&gt;\"+testData.num);\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4ee3\u7801\u7b80\u5355\u89e3\u91ca\u4e00\u4e0b\uff0c\u5206\u4e24\u79cd\u60c5\u51b5\uff0c\u5927\u5bb6\u53ef\u4ee5\u81ea\u5df1\u6539\u52a8\u8fdb\u884c\u6d4b\u8bd5\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>TestData \u4e2d\u7684 num \u5982\u679c\u4e0d\u6dfb\u52a0 volatile \u5173\u952e\u5b57\uff0cSystem.out.println(&#8220;MainThread num&#8211;&gt;&#8221;+testData.num);\u8fd9\u4e00\u53e5\u4e00\u76f4\u4e0d\u4f1a\u6267\u884c\u3002\u8868\u793a while \u4e2d\u7684\u6761\u4ef6 testData.num == 0 \u4e00\u76f4\u4e3a 0\uff0c\u5b50\u7ebf\u7a0b\u4fee\u6539\u4e86num \u5bf9\u4e3b\u7ebf\u7a0b\u4e0d\u8d77\u4f5c\u7528\u3002<\/li><li> TestData \u4e2d\u7684 num \u5982\u679c\u6dfb\u52a0\u4e86 volatile \u5173\u952e\u5b57\uff0cSystem.out.println(&#8220;MainThread num&#8211;&gt;&#8221;+testData.num); \u4f1a\u6267\u884c\uff0c\u7ed3\u679c\u5982\u4e0b\u3002<\/li><\/ol>\n\n\n\n<pre class=\"wp-block-code\"><code>ChildThread num--&gt;0\nChildThread update num--&gt;1\nMainThread num--&gt;1<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">volatile \u662f\u975e\u539f\u5b50\u6027\u7684\uff0c\u5373\u5b83\u4e0d\u5177\u5907\u539f\u5b50\u6027\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>use \u548c assign \u8fd9\u4e24\u4e2a\u64cd\u4f5c\u6574\u4f53\u4e0a\u4e0d\u662f\u4e00\u4e2a\u8fde\u7eed\u6027\u7684\u539f\u5b50\u64cd\u4f5c\u3002volatile \u672c\u8eab\u5e76\u4e0d\u5bf9\u6570\u636e\u8fd0\u7b97\u5904\u7406\u7ef4\u6301\u539f\u5b50\u6027\uff0c\u5f3a\u8c03\u7684\u662f\u8bfb\u5199\u53ca\u65f6\u5f71\u54cd\u4e3b\u5b58\u3002<\/li><li>\u975e\u539f\u5b50\u6027\u64cd\u4f5c\u4e3e\u4f8b\uff1avolatile \u4fee\u9970 num\uff0cnum++\uff1bnum = num+1\uff1b\u8fd9\u79cd\u5c31\u662f\u975e\u539f\u5b50\u6027\u64cd\u4f5c\u3002\u5b83\u662f\u5206\u6b65\u8fdb\u884c\u64cd\u4f5c\u7684\uff1a\u5148\u4e3b\u5b58\u8bfb\u53d6 num \u7684\u503c\uff1b\u518d\u8fdb\u884c num++ \u8fd0\u7b97\uff1b\u7136\u540e\u5c06 num \u503c\u5199\u5230\u4e3b\u5b58\u3002<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u50cf\u79cd\u64cd\u4f5c\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e2d\uff0cuse \u548c assign \u662f\u591a\u6b21\u51fa\u73b0\uff0c\u5982\u679c\u6709\u4e24\u4e2a\u7ebf\u7a0b\u4e2d\u8bfb\u53d6\u5230\u4e3b\u5b58\u7684 num \u90fd\u662f 2\uff0c\u4e14\u540c\u65f6\u6267\u884c num++\uff0c\u4e24\u4e2a\u7ebf\u7a0b\u7684\u7ed3\u679c\u90fd\u662f 3\uff0c\u8fd9\u6837\u5c31\u4ea7\u751f\u4e86\u810f\u6570\u636e\uff0c\u518d\u5199\u5165\u4e3b\u5b58\u4e2d\u90fd\u662f 3\u3002\u6838\u5fc3 num++ \u8fd0\u7b97\u5e76\u6ca1\u4fdd\u8bc1\u5148\u540e\u987a\u5e8f\u6267\u884c\u3002\u4e3a\u4e86\u4fdd\u8bc1\u6267\u884c\u8fd0\u7b97\u7684\u7ebf\u7a0b\u987a\u5e8f\uff0c\u53ef\u4ee5\u9009\u62e9 synchronize\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0b\u9762\u4f7f\u7528\u4e00\u6bb5 Java \u4ee3\u7801\u9a8c\u8bc1 volatile \u7684\u975e\u539f\u5b50\u6027\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class ValatileAtomic {\n    public static class TestData {\n        volatile int num = 0;\n        \/\/synchronized\n        public void updateNum(){\n            num++;\n        }\n    }\n    public static void main(String[] args) {\n        final TestData testData = new TestData();\n        for(int i = 1; i &lt;= 10; i++) {\n            new Thread(new Runnable() {\n                @Override\n                public void run() {\n                    for (int j = 1; j &lt;= 1000; j++) {\n                        testData.updateNum();\n                    }\n                }\n            }).start();\n        }\n        while (Thread.activeCount() &gt; 2) {\n            Thread.yield();\n        }\n        System.out.println(\"\u6700\u7ec8\u7ed3\u679c\uff1a\" + testData.num);\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u6309\u6211\u4eec\u7684\u610f\u613f\u521b\u5efa 10 \u4e2a\u7ebf\u7a0b\uff0c\u6bcf\u4e2a\u7ebf\u7a0b\u7d2f\u52a0\u7ebf\u7a0b\u7d2f\u52a0 1000\uff0c\u4e00\u5171\u662f 10 * 1000 = 10000\u3002\u4f46\u662f volatile int num = 0; \u4f7f\u7528 volatile \u4e0e\u5426\u90fd\u662f\u4f53\u73b0\u975e\u539f\u5b50\u6027\uff0c\u8fd0\u884c\u7684\u7ed3\u679c\u90fd\u6bd4 10000 \u5c0f\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\u6700\u7ec8\u7ed3\u679c\uff1a9701<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3a\u4e86\u5b9e\u73b0\u540c\u6b65\u64cd\u4f5c\uff0c\u5728\u65b9\u6cd5 updateNum() \u524d\u6dfb\u52a0\u5173\u952e\u5b57 synchronize \u5373\u53ef\uff0c\u52a0\u4e86\u5173\u952e\u5b57\u4e4b\u540e\uff0c\u7ed3\u679c\u5c31\u7b26\u5408\u6211\u4eec\u7684\u9884\u671f\u4e86\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\u6700\u7ec8\u7ed3\u679c\uff1a10000<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">volatile \u7684\u6709\u5e8f\u6027\uff0cvolatile \u80fd\u591f\u7981\u6b62\u6307\u4ee4\u91cd\u6392\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6307\u4ee4\u91cd\u6392\u662f\u6307\uff1a\u4e3a\u4e86\u63d0\u9ad8\u6027\u80fd\uff0c\u7f16\u8bd1\u5668\u548c\u548c\u5904\u7406\u5668\u901a\u5e38\u4f1a\u5bf9\u6307\u4ee4\u8fdb\u884c\u6307\u4ee4\u91cd\u6392\u5e8f\u3002<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter\"><img decoding=\"async\" src=\"https:\/\/images.weserv.nl\/?url=https:\/\/wx2.sinaimg.cn\/mw690\/8fa5dcfcgy1gaswg0hizzj21bw05076m.jpg\" alt=\"\" \/><figcaption>volatile \u7684\u6709\u5e8f\u6027\u548c\u7981\u6b62\u6307\u4ee4\u91cd\u6392<\/figcaption><\/figure><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0a\u56fe\u4e2d\u7684\u4e09\u4e2a\u91cd\u6392\u4f4d\u7f6e\u53ef\u4ee5\u8c03\u6362\u7684\uff0c\u6839\u636e\u7cfb\u7edf\u4f18\u5316\u9700\u8981\u8fdb\u884c\u91cd\u6392\u3002\u9075\u5faa\u7684\u539f\u5219\u662f\u5355\u7ebf\u7a0b\u91cd\u6392\u540e\u7684\u6267\u884c\u7ed3\u679c\u8981\u4e0e\u987a\u5e8f\u6267\u884c\u7ed3\u679c\u76f8\u540c\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5185\u5b58\u5c4f\u969c\u6307\u4ee4\uff1avolatile \u5728\u6307\u4ee4\u4e4b\u95f4\u63d2\u5165\u5185\u5b58\u5c4f\u969c\uff0c\u4fdd\u8bc1\u6309\u7167\u7279\u5b9a\u987a\u5e8f\u6267\u884c\u548c\u67d0\u4e9b\u53d8\u91cf\u7684\u53ef\u89c1\u6027\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">volatile \u5c31\u662f\u901a\u8fc7\u5185\u5b58\u5c4f\u969c\u901a\u77e5 cpu \u548c\u7f16\u8bd1\u5668\u4e0d\u505a\u6307\u4ee4\u91cd\u6392\u4f18\u5316\u6765\u7ef4\u6301\u6709\u5e8f\u6027\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0e synchronize \u7684\u4e32\u884c\u63a7\u5236\u7684\u533a\u522b\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>synchronize \u65e0\u7981\u6b62\u6307\u4ee4\u91cd\u6392\u3002<\/li><li> \u4e00\u4e2a\u53d8\u91cf\u5728\u540c\u4e00\u65f6\u523b\u53ea\u5141\u8bb8\u4e00\u6761\u7ebf\u7a0b\u5bf9\u5176\u8fdb\u884c lock \u64cd\u4f5c\uff0c\u83b7\u53d6\u5bf9\u8c61\u9501\uff0c\u4e92\u65a5\u6392\u4ed6\u6027\u8fbe\u5230\u4e24\u4e2a\u540c\u6b65\u5757\u4e32\u884c\u6267\u884c\u3002<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">volatile \u7684\u7ebf\u7a0b\u5b89\u5168\u9002\u7528\u8303\u56f4\u662f\u6709\u6761\u4ef6\u7684\u3002\u7531\u4e8e volatile \u7684\u975e\u539f\u5b50\u6027\u539f\u56e0\uff0c\u6240\u4ee5\u5b83\u7684\u7ebf\u7a0b\u5b89\u5168\u662f\u6709\u6761\u4ef6\u7684\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>\u8fd0\u7b97\u7ed3\u679c\u4e0d\u4f9d\u8d56\u4f46\u524d\u7f6e\uff0c\u6216\u8005\u80fd\u4fdd\u8bc1\u81ea\u7531\u4e00\u4e2a\u5355\u4e00\u7ebf\u7a0b\u4fee\u6539\u53d8\u91cf\u503c\u3002<\/li><li>\u53d8\u91cf\u4e0d\u9700\u8981\u4e0e\u5176\u4ed6\u7684\u72b6\u6001\u53d8\u91cf\u5171\u540c\u53c2\u4e0e\u4e0d\u53d8\u7684\u7ea6\u675f\u3002 \u8fd9\u4e24\u6761\u4ef6\u63cf\u8ff0\u51fa\u81ea\u4e8e\u300a\u6df1\u5165\u7406\u89e3java\u865a\u62df\u673a\u300b\u3002<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">volatile \u4e0e synchronize \u914d\u5408\u4f7f\u7528\uff0c\u5148\u770b\u4e00\u4e2a DCL\uff08Double Check Lock\uff09 \u5355\u4f8b\u4ee3\u7801\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class Singleton {\n    private volatile static Singleton instance = null;\n    private Singleton(){}\n    public static Singleton getInstance(){\n        if(instance == null){ \/\/ \u7b2c\u2460\u5904\n            synchronized (Singleton.class) {\n                if(instance == null){  \/\/ \u7b2c\u2461\u5904\n                    instance = new Singleton();\n                }\n            }\n        }\n        return instance;\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0a\u9762\u7684\u4ee3\u7801\u4e3a\u4ec0\u4e48\u8fd8\u8981\u4f7f\u7528 volatile \u6765\u4fee\u9970\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6309\u7167\u6211\u4eec\u4e0a\u8fb9\u7684\u5199\u6cd5\u5df2\u7ecf\u5bf9 new Singleton(); \u8fd9\u4e2a\u64cd\u4f5c\u8fdb\u884c\u4e86 synchronize \u64cd\u4f5c\uff0c\u5df2\u7ecf\u4fdd\u8bc1\u4e86\u591a\u7ebf\u7a0b\u53ea\u80fd\u4e32\u884c\u6267\u884c\u8fd9\u4e2a\u5b9e\u4f8b\u5316\u4ee3\u7801\u3002\u4e8b\u5b9e\u4e0a\uff0csynchronize \u4fdd\u8bc1\u4e86\u7ebf\u7a0b\u6267\u884c\u5b9e\u4f8b\u5316\u8fd9\u6bb5\u4ee3\u7801\u662f\u4e32\u884c\u7684\uff0c\u4f46\u662f synchronize \u5e76\u4e0d\u5177\u5907\u7981\u6b62\u6307\u4ee4\u91cd\u6392\u7684\u7279\u6027\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u800c instance = new Singleton(); \u4e3b\u8981\u505a\u4e86 3 \u4ef6\u4e8b\u60c5\uff1a<\/p>\n\n\n\n<ol><li>java \u865a\u62df\u673a\u4e3a\u5bf9\u8c61\u5206\u914d\u4e00\u5757\u5185\u5b58 x\u3002<\/li><li> \u5728\u5185\u5b58 x \u4e0a\u4e3a\u5bf9\u8c61\u8fdb\u884c\u521d\u59cb\u5316\u3002<\/li><li> \u5c06\u5185\u5b58 x \u7684\u5730\u5740\u8d4b\u503c\u7ed9 instance \u53d8\u91cf\u3002<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u5982\u679c\u7f16\u8bd1\u5668\u8fdb\u884c\u91cd\u6392\u4e3a\uff1a<\/p>\n\n\n\n<ol><li>java \u865a\u62df\u673a\u4e3a\u5bf9\u8c61\u5206\u914d\u4e00\u5757\u5185\u5b58 x\u3002<\/li><li> \u5c06\u5185\u5b58 x \u7684\u5730\u5740\u8d4b\u503c\u7ed9 instance \u53d8\u91cf\u3002<\/li><li> \u5728\u5185\u5b58 x \u4e0a\u4e3a\u5bf9\u8c61\u8fdb\u884c\u521d\u59cb\u5316\u3002<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b2c\u4e00\u79cd\u60c5\u51b5\uff0c\u65e0 volatile \u4fee\u9970\uff1a\u6b64\u65f6\uff0c\u6709\u4e24\u4e2a\u7ebf\u7a0b\u6267\u884c getInstance() \u65b9\u6cd5\uff0c\u52a0\u5165\u7ebf\u7a0b A \u8fdb\u5165\u4ee3\u7801\u7684\u6ce8\u91ca\u4e2d\u7684\u7b2c\u2461\u5904\uff0c\u5e76\u6267\u884c\u5230\u4e86\u91cd\u6392\u6307\u4ee4\u7684\uff082\uff09\uff0c\u4e0e\u5176\u540c\u65f6\u7ebf\u7a0bB\u521a\u597d\u4ee3\u7801\u6ce8\u91ca\u4e2d\u7684\u7b2c\u2460\u5904\u7684 if \u5224\u65ad\u3002\u6b64\u65f6\uff0cinstance \u6709\u7ebf\u7a0b A \u628a\u5185\u5b58\u5730\u5740 x \u5730\u5740\u8d4b\u503c\u7ed9\u4e86 instance\uff0c\u90a3\u4e48 instance \u5df2\u7ecf\u4e0d\u4e3a\u7a7a\u53ea\u662f\u6ca1\u6709\u521d\u59cb\u5316\u5b8c\u6210\uff0c\u7ebf\u7a0b B \u5c31\u8fd4\u56de\u4e86\u4e00\u4e2a\u6ca1\u6709\u5b8c\u6210\u521d\u59cb\u5316\u7684 instance\uff0c\u6700\u7ec8\u4f7f\u7528\u65f6\u5019\u4f1a\u51fa\u73b0\u7a7a\u6307\u9488\u7684\u9519\u8bef\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b2c\u4e8c\u79cd\u60c5\u51b5\uff0c\u6709 volatile \u4fee\u9970\uff1ainstance \u56e0\u4e3a\u88ab volatile \u7684\u7981\u6b62\u6307\u4ee4\u91cd\u6392\u7684\u7279\u6027\uff0c\u90a3\u53ea\u4f1a\u5b89\u88c5\u5148\u521d\u59cb\u5316\u5bf9\u8c61\u518d\u8d4b\u503c\u7ed9 instance \u8fd9\u6837\u987a\u5e8f\u6267\u884c\uff0c\u8fd9\u6837\u5c31\u80fd\u4fdd\u8bc1\u8fd4\u56de\u6b63\u5e38\u7684\u5b9e\u4f8b\u5316\u7684\u5bf9\u8c61\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6700\u540e\u505a\u4e2a\u603b\u7ed3\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>volatile \u5177\u6709\u53ef\u89c1\u6027\u548c\u6709\u5e8f\u6027\uff0c\u4e0d\u80fd\u4fdd\u8bc1\u539f\u5b50\u6027\u3002<\/li><li>volatile \u5728\u7279\u5b9a\u60c5\u51b5\u4e0b\u7ebf\u7a0b\u5b89\u5168\uff0c\u6bd4\u5982\u81ea\u8eab\u4e0d\u505a\u975e\u539f\u5b50\u6027\u8fd0\u7b97\u3002<\/li><li>synchronize \u901a\u8fc7\u83b7\u53d6\u5bf9\u8c61\u9501\uff0c\u4fdd\u8bc1\u4ee3\u7801\u5757\u4e32\u884c\u6267\u884c\uff0c\u65e0\u7981\u6b62\u6307\u4ee4\u91cd\u6392\u80fd\u529b\u3002<\/li><li>DCL \u5355\u4f8b\u64cd\u4f5c\u9700\u8981 volatile \u548c synchronize \u4fdd\u8bc1\u7ebf\u7a0b\u5b89\u5168\u3002<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u53c2\u8003\u8d44\u6599\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><a href=\"https:\/\/zh.wikipedia.org\/zh-hans\/Volatile%E5%8F%98%E9%87%8F\">https:\/\/zh.wikipedia.org\/zh-hans\/Volatile%E5%8F%98%E9%87%8F<\/a><\/li><li><a rel=\"noreferrer noopener\" aria-label=\"\uff08\u5728\u65b0\u7a97\u53e3\u6253\u5f00\uff09\" href=\"https:\/\/baike.baidu.com\/item\/volatile\" target=\"_blank\">https:\/\/baike.baidu.com\/item\/volatile<\/a><\/li><li><a rel=\"noreferrer noopener\" aria-label=\"\uff08\u5728\u65b0\u7a97\u53e3\u6253\u5f00\uff09\" href=\"https:\/\/juejin.im\/post\/5e17a5735188254c0a0409f1\" target=\"_blank\">https:\/\/juejin.im\/post\/5e17a5735188254c0a0409f1<\/a><\/li><li><a href=\"https:\/\/www.ibm.com\/developerworks\/cn\/java\/j-jtp06197.html\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"\uff08\u5728\u65b0\u7a97\u53e3\u6253\u5f00\uff09\">https:\/\/www.ibm.com\/developerworks\/cn\/java\/j-jtp06197.html<\/a><\/li><\/ul>\n<!-- <audio autoplay=\"autoplay\" height=\"100\" width=\"100\" hidden=\"true\"><source src=\"https:\/\/c.coka.la\/orAvPR.mp3\" type=\"audio\/mp3\"\/><\/audio><img decoding=\"async\" src=\"https:\/\/images.weserv.nl\/?url=https:\/\/ws3.sinaimg.cn\/large\/8fa5dcfcgy1g4em3rzar5j20ib089ae0.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/> --><p><!-- <img decoding=\"async\" src=\"https:\/\/raw.githubusercontent.com\/xmt1139057136\/xttblog\/master\/8fa5dcfcgy1g4em3rzar5j20ib089ae0.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/>--><img decoding=\"async\" src=\"https:\/\/saas.51autoparts.cn\/api\/admin\/sys-file\/oss\/file?fileName=84db51f8561e448f9a4fda2eff0811f9.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/><\/p><p>\u6700\u540e\uff0c\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u4e2a\u4eba\u5fae\u4fe1\u516c\u4f17\u53f7\uff1a\u4e1a\u4f59\u8349\uff08yyucao\uff09\uff01<b>\u53ef\u52a0\u4f5c\u8005\u5fae\u4fe1\u53f7\uff1a<font color=\"red\">xttblog2<\/font>\u3002\u5907\u6ce8\uff1a\u201c1\u201d\uff0c\u6dfb\u52a0\u535a\u4e3b\u5fae\u4fe1\u62c9\u4f60\u8fdb\u5fae\u4fe1\u7fa4\u3002\u5907\u6ce8\u9519\u8bef\u4e0d\u4f1a\u540c\u610f\u597d\u53cb\u7533\u8bf7\u3002<\/b>\u518d\u6b21\u611f\u8c22\u60a8\u7684\u5173\u6ce8\uff01\u540e\u7eed\u6709\u7cbe\u5f69\u5185\u5bb9\u4f1a\u7b2c\u4e00\u65f6\u95f4\u53d1\u7ed9\u60a8\uff01\u539f\u521b\u6587\u7ae0\u6295\u7a3f\u8bf7\u53d1\u9001\u81f3532009913@qq.com\u90ae\u7bb1\u3002\u5546\u52a1\u5408\u4f5c\u4e5f\u53ef\u6dfb\u52a0\u4f5c\u8005\u5fae\u4fe1\u8fdb\u884c\u8054\u7cfb\uff01<\/p><p>\u672c\u6587\u539f\u6587\u51fa\u5904\uff1a<a href=\"https:\/\/www.xttblog.com\">\u4e1a\u4f59\u8349<\/a>\uff1a &raquo; <a href=\"https:\/\/www.xttblog.com\/?p=4633\">volatile\u53ef\u89c1\u6027\u539f\u7406\u6700\u5f3a\u603b\u7ed3<\/a><\/p><!-- <div class=\"bd-reward-stl\"><button id=\"bdRewardBtn\"><span><\/span><\/button><\/div> -->","protected":false},"excerpt":{"rendered":"<p>\u6700\u8fd1\u770b\u5230\u4e00\u7bc7\u5f88\u597d\u7684 volatile \u53ef\u89c1\u6027\u539f\u7406\u603b\u7ed3\uff0c\u5206\u4eab\u7ed9\u5927\u5bb6\uff01 volatile \u662f\u4e00\u79cd\u8f7b\u91cf\u4e14\u5728\u6709\u9650\u7684\u6761\u4ef6 [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[565,426,1335,531,1931],"class_list":["post-4633","post","type-post","status-publish","format-standard","hentry","category-java","tag-java-","tag-synchronized","tag-volatile","tag-531","tag-1931"],"_links":{"self":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4633","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4633"}],"version-history":[{"count":2,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4633\/revisions"}],"predecessor-version":[{"id":4635,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4633\/revisions\/4635"}],"wp:attachment":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4633"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4633"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4633"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}