{"id":10431,"date":"2023-11-28T21:34:37","date_gmt":"2023-11-28T13:34:37","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=10431"},"modified":"2023-12-07T11:25:28","modified_gmt":"2023-12-07T03:25:28","slug":"jvm-zhong-zhi-ling-zhong-pai-xu","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/11\/28\/jvm-zhong-zhi-ling-zhong-pai-xu\/","title":{"rendered":"JVM\u4e2d\u6307\u4ee4\u91cd\u6392\u5e8f\uff1f"},"content":{"rendered":"<p>\u6307\u4ee4\u91cd\u6392\u5e8f\u662f\u4e00\u79cd\u7f16\u8bd1\u5668\u548c\u5904\u7406\u5668\u4e3a\u4e86\u63d0\u9ad8\u6027\u80fd\u800c\u5bf9\u6307\u4ee4\u5e8f\u5217\u8fdb\u884c\u91cd\u65b0\u6392\u5e8f\u7684\u4f18\u5316\u6280\u672f\u3002\u91cd\u6392\u5e8f\u4e0d\u4f1a\u6539\u53d8\u5355\u7ebf\u7a0b\u7a0b\u5e8f\u7684\u6267\u884c\u7ed3\u679c\uff0c\u4f46\u53ef\u80fd\u4f1a\u5f71\u54cd\u591a\u7ebf\u7a0b\u7a0b\u5e8f\u7684\u6b63\u786e\u6027\u3002Java\u5185\u5b58\u6a21\u578b\u901a\u8fc7\u63d0\u4f9b\u4e00\u4e9b\u89c4\u5219\u548c\u7ea6\u675f\u6765\u7981\u6b62\u4e00\u4e9b\u53ef\u80fd\u5bfc\u81f4\u591a\u7ebf\u7a0b\u7a0b\u5e8f\u51fa\u73b0\u95ee\u9898\u7684\u6307\u4ee4\u91cd\u6392\u5e8f\u3002<\/p>\n<p>Java\u7a0b\u5e8f\u5458\u901a\u5e38\u662f\u5728\u4f7f\u7528volatile\u5173\u952e\u5b57\u3001synchronized\u5173\u952e\u5b57\u3001final\u5173\u952e\u5b57\u7b49\u624b\u6bb5\u6765\u4fdd\u969c\u7a0b\u5e8f\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e2d\u7684\u6b63\u786e\u6027\uff0c\u5176\u4e2d\u5c31\u5305\u542b\u4e86\u5bf9\u6307\u4ee4\u91cd\u6392\u5e8f\u7684\u4e00\u4e9b\u89c4\u8303\u3002<\/p>\n<p>\u4ee5\u4e0b\u662f\u4e00\u4e9b\u6307\u4ee4\u91cd\u6392\u5e8f\u7684\u4f8b\u5b50\uff1a<\/p>\n<ol>\n<li>\n<strong>\u7f16\u8bd1\u5668\u91cd\u6392\u5e8f\uff1a<\/strong><\/p>\n<pre><code class=\"language-java\">class ReorderExample {\n    int x = 0;\n    boolean flag = false;\n\n    public void write() {\n        x = 42;\n        flag = true;\n    }\n\n    public void read() {\n        if (flag) {\n            System.out.println(x);\n        }\n    }\n}\n<\/code><\/pre>\n<p>\u5728<code>write<\/code>\u65b9\u6cd5\u4e2d\uff0c\u7f16\u8bd1\u5668\u53ef\u80fd\u4f1a\u5148\u6267\u884c<code>flag = true<\/code>\uff0c\u7136\u540e\u518d\u6267\u884c<code>x = 42<\/code>\u3002\u5728<code>read<\/code>\u65b9\u6cd5\u4e2d\uff0c\u7531\u4e8e<code>flag<\/code>\u5df2\u7ecf\u88ab\u91cd\u6392\u5e8f\u5230\u524d\u9762\uff0c\u53ef\u80fd\u4f1a\u5bfc\u81f4<code>x<\/code>\u8f93\u51fa\u4e3a0\u3002\n<\/li>\n<li>\n<strong>\u5904\u7406\u5668\u91cd\u6392\u5e8f\uff1a<\/strong><\/p>\n<pre><code class=\"language-java\">class ReorderExample {\n    int a = 0;\n    volatile boolean flag = false;\n\n    public void write() {\n        a = 1;\n        flag = true;\n    }\n\n    public void read() {\n        if (flag) {\n            System.out.println(a);\n        }\n    }\n}\n<\/code><\/pre>\n<p>\u5728<code>write<\/code>\u65b9\u6cd5\u4e2d\uff0c\u5904\u7406\u5668\u53ef\u80fd\u4f1a\u5148\u6267\u884c<code>a = 1<\/code>\uff0c\u7136\u540e\u518d\u6267\u884c<code>flag = true<\/code>\u3002\u5728<code>read<\/code>\u65b9\u6cd5\u4e2d\uff0c\u7531\u4e8e<code>flag<\/code>\u662fvolatile\u7684\uff0c\u8bfb\u53d6<code>flag<\/code>\u4f1a\u5f3a\u5236\u5728\u8bfb\u53d6<code>a<\/code>\u4e4b\u524d\u53d1\u751f\u3002\n<\/li>\n<\/ol>\n<p>Java\u5185\u5b58\u6a21\u578b\u89c4\u5b9a\u4e86\u4e00\u7cfb\u5217 happens-before \u7684\u5173\u7cfb\uff0c\u5305\u62ec\u5bf9volatile\u5b57\u6bb5\u7684\u8bfb\u5199\u64cd\u4f5c\u3001synchronized\u5757\u7684\u8fdb\u5165\u548c\u9000\u51fa\u7b49\uff0c\u8fd9\u4e9b\u5173\u7cfb\u63d0\u4f9b\u4e86\u4e00\u4e9b\u4fdd\u8bc1\uff0c\u9632\u6b62\u4e86\u4e00\u4e9b\u53ef\u80fd\u7684\u91cd\u6392\u5e8f\u3002\u56e0\u6b64\uff0c\u5408\u7406\u4f7f\u7528volatile\u3001synchronized\u7b49\u673a\u5236\u53ef\u4ee5\u907f\u514d\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u7684\u6307\u4ee4\u91cd\u6392\u5e8f\u95ee\u9898\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6307\u4ee4\u91cd\u6392\u5e8f\u662f\u4e00\u79cd\u7f16\u8bd1\u5668\u548c\u5904\u7406\u5668\u4e3a\u4e86\u63d0\u9ad8\u6027\u80fd\u800c\u5bf9\u6307\u4ee4\u5e8f\u5217\u8fdb\u884c\u91cd\u65b0\u6392\u5e8f\u7684\u4f18\u5316\u6280\u672f\u3002\u91cd\u6392\u5e8f\u4e0d\u4f1a\u6539\u53d8\u5355\u7ebf\u7a0b\u7a0b\u5e8f\u7684\u6267\u884c\u7ed3 [&hellip;]<\/p>\n","protected":false},"author":9,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[119],"tags":[],"class_list":["post-10431","post","type-post","status-publish","format-standard","hentry","category-jvm"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/10431","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=10431"}],"version-history":[{"count":2,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/10431\/revisions"}],"predecessor-version":[{"id":16838,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/10431\/revisions\/16838"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=10431"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=10431"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=10431"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}