{"id":151,"date":"2024-12-08T22:37:53","date_gmt":"2024-12-08T22:37:53","guid":{"rendered":"https:\/\/www.isvmspace.com\/?p=151"},"modified":"2024-12-08T22:37:53","modified_gmt":"2024-12-08T22:37:53","slug":"jvm%e7%b3%bb%e5%88%97-java%e5%86%85%e5%ad%98%e6%a8%a1%e5%9e%8b%ef%bc%88jmm%ef%bc%89","status":"publish","type":"post","link":"https:\/\/www.isvmspace.com\/?p=151","title":{"rendered":"JVM\u7cfb\u5217-Java\u5185\u5b58\u6a21\u578b\uff08JMM\uff09"},"content":{"rendered":"<h1>\u4ec0\u4e48\u662fJMM\u6a21\u578b<\/h1>\n<p>Java\u5185\u5b58\u6a21\u578b(Java\u00a0Memory\u00a0Model\u7b80\u79f0JMM)\u662f\u4e00\u79cd\u62bd\u8c61\u7684\u6982\u5ff5\uff0c\u5e76\u4e0d\u771f\u5b9e\u5b58\u5728\uff0c\u5b83\u63cf\u8ff0\u7684\u662f\u4e00\u7ec4\u89c4\u5219\u6216\u89c4\u8303\uff0c\u901a\u8fc7\u8fd9\u7ec4\u89c4\u8303\u5b9a\u4e49\u4e86\u7a0b\u5e8f\u4e2d\u5404\u4e2a\u53d8\u91cf\uff08\u5305\u62ec\u5b9e\u4f8b\u5b57\u6bb5\uff0c\u9759\u6001\u5b57\u6bb5\u548c\u6784\u6210\u6570\u7ec4\u5bf9\u8c61\u7684\u5143\u7d20\uff09\u7684\u8bbf\u95ee\u65b9\u5f0f\u3002<br \/>\nJMM\u7528\u6765\u5c4f\u853d\u6389\u5404\u79cd\u786c\u4ef6\u548c\u64cd\u4f5c\u7cfb\u7edf\u7684\u5185\u5b58\u8bbf\u95ee\u5dee\u5f02\uff0c\u4ee5\u5b9e\u73b0\u8ba9Java\u7a0b\u5e8f\u5728\u5404\u4e2a\u5e73\u53f0\u4e0b\u90fd\u80fd\u4e00\u81f4\u7684\u5185\u5b58\u8bbf\u95ee\u6548\u679c\u3002JMM\u662f\u56f4\u7ed5\u7740\u539f\u5b50\u6027\uff0c\u6709\u5e8f\u6027\u3001\u53ef\u89c1\u6027\u5efa\u7acb\u7684<\/p>\n<ul>\n<li>\u539f\u5b50\u6027\uff1a\u5c31\u662f\u8bf4\u4e00\u4e2a\u64cd\u4f5c\u4e0d\u80fd\u88ab\u6253\u65ad\uff0c\u8981\u4e48\u6267\u884c\u5b8c\u8981\u4e48\u4e0d\u6267\u884c\uff0c\u7c7b\u4f3c\u4e8b\u52a1\u64cd\u4f5c\uff0cJava \u57fa\u672c\u7c7b\u578b\u6570\u636e\u7684\u8bbf\u95ee\u5927\u90fd\u662f\u539f\u5b50\u64cd\u4f5c\uff0clong \u548c double \u7c7b\u578b\u662f 64 \u4f4d\uff0c\u5728 32 \u4f4d JVM \u4e2d\u4f1a\u5c06 64 \u4f4d\u6570\u636e\u7684\u8bfb\u5199\u64cd\u4f5c\u5206\u6210\u4e24\u6b21 32 \u4f4d\u6765\u5904\u7406\uff0c\u6240\u4ee5 long \u548c double \u5728 32 \u4f4d JVM \u4e2d\u662f\u975e\u539f\u5b50\u64cd\u4f5c\uff0c\u4e5f\u5c31\u662f\u8bf4\u5728\u5e76\u53d1\u8bbf\u95ee\u65f6\u662f\u7ebf\u7a0b\u975e\u5b89\u5168\u7684\uff0c\u8981\u60f3\u4fdd\u8bc1\u539f\u5b50\u6027\u5c31\u5f97\u5bf9\u8bbf\u95ee\u8be5\u6570\u636e\u7684\u5730\u65b9\u8fdb\u884c\u540c\u6b65\u64cd\u4f5c\uff0c\u8b6c\u5982 synchronized \u7b49\u3002<\/li>\n<li>\u6709\u5e8f\u6027\uff1a\u5c31\u662f\u8bf4 Java \u5185\u5b58\u6a21\u578b\u4e2d\u7684\u6307\u4ee4\u91cd\u6392\u4e0d\u4f1a\u5f71\u54cd\u5355\u7ebf\u7a0b\u7684\u6267\u884c\u987a\u5e8f\uff0c\u4f46\u662f\u4f1a\u5f71\u54cd\u591a\u7ebf\u7a0b\u5e76\u53d1\u6267\u884c\u7684\u6b63\u786e\u6027\uff0c\u6240\u4ee5\u5728\u5e76\u53d1\u4e2d\u6211\u4eec\u5fc5\u987b\u8981\u60f3\u529e\u6cd5\u4fdd\u8bc1\u5e76\u53d1\u4ee3\u7801\u7684\u6709\u5e8f\u6027\uff1b\u5728 Java \u91cc\u53ef\u4ee5\u901a\u8fc7 volatile \u5173\u952e\u5b57\u4fdd\u8bc1\u4e00\u5b9a\u7684\u6709\u5e8f\u6027\uff0c\u8fd8\u53ef\u4ee5\u901a\u8fc7 synchronized\u3001Lock \u6765\u4fdd\u8bc1\u6709\u5e8f\u6027\uff0c\u56e0\u4e3a synchronized\u3001Lock \u4fdd\u8bc1\u4e86\u6bcf\u4e00\u65f6\u523b\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u6267\u884c\u540c\u6b65\u4ee3\u7801\u76f8\u5f53\u4e8e\u5355\u7ebf\u7a0b\u6267\u884c\uff0c\u6240\u4ee5\u81ea\u7136\u4e0d\u4f1a\u6709\u6709\u5e8f\u6027\u7684\u95ee\u9898\uff1b\u9664\u6b64\u4e4b\u5916 Java \u5185\u5b58\u6a21\u578b\u901a\u8fc7 happens-before \u539f\u5219\u5982\u679c\u80fd\u63a8\u5bfc\u51fa\u6765\u4e24\u4e2a\u64cd\u4f5c\u7684\u6267\u884c\u987a\u5e8f\u5c31\u80fd\u5148\u5929\u4fdd\u8bc1\u6709\u5e8f\u6027\uff0c\u5426\u5219\u65e0\u6cd5\u4fdd\u8bc1\uff0c\u5173\u4e8e happens-before \u539f\u5219\u53ef\u4ee5\u67e5\u9605\u76f8\u5173\u8d44\u6599\u3002<\/li>\n<li>\u53ef\u89c1\u6027\uff1a\u5c31\u662f\u8bf4\u5f53\u4e00\u4e2a\u7ebf\u7a0b\u5bf9\u5171\u4eab\u53d8\u91cf\u505a\u4e86\u4fee\u6539\u540e\u5176\u4ed6\u7ebf\u7a0b\u53ef\u4ee5\u7acb\u5373\u611f\u77e5\u5230\u8be5\u5171\u4eab\u53d8\u91cf\u7684\u6539\u53d8\uff0c\u4ece Java \u5185\u5b58\u6a21\u578b\u6211\u4eec\u5c31\u80fd\u770b\u51fa\u6765\u591a\u7ebf\u7a0b\u8bbf\u95ee\u5171\u4eab\u53d8\u91cf\u90fd\u8981\u7ecf\u8fc7\u7ebf\u7a0b\u5de5\u4f5c\u5185\u5b58\u5230\u4e3b\u5b58\u7684\u590d\u5236\u548c\u4e3b\u5b58\u5230\u7ebf\u7a0b\u5de5\u4f5c\u5185\u5b58\u7684\u590d\u5236\u64cd\u4f5c\uff0c\u6240\u4ee5\u666e\u901a\u5171\u4eab\u53d8\u91cf\u5c31\u65e0\u6cd5\u4fdd\u8bc1\u53ef\u89c1\u6027\u4e86\uff1bJava \u63d0\u4f9b\u4e86 volatile \u4fee\u9970\u7b26\u6765\u4fdd\u8bc1\u53d8\u91cf\u7684\u53ef\u89c1\u6027\uff0c\u6bcf\u6b21\u4f7f\u7528 volatile \u53d8\u91cf\u90fd\u4f1a\u4e3b\u52a8\u4ece\u4e3b\u5b58\u4e2d\u5237\u65b0\uff0c\u9664\u6b64\u4e4b\u5916 synchronized\u3001Lock\u3001final \u90fd\u53ef\u4ee5\u4fdd\u8bc1\u53d8\u91cf\u7684\u53ef\u89c1\u6027\u3002<\/li>\n<\/ul>\n<p><img decoding=\"async\" src=\"https:\/\/www.isvmspace.com\/wp-content\/uploads\/2023\/02\/JMM\u56fe.png\" alt=\"\" \/><\/p>\n<h1>Java\u5185\u5b58\u6a21\u578b\u4e0e\u5185\u5b58\u4ea4\u4e92\u64cd\u4f5c<\/h1>\n<p><img decoding=\"async\" src=\"https:\/\/www.isvmspace.com\/wp-content\/uploads\/2023\/02\/JMM\u5185\u5b58\u4ea4\u4e92.png\" alt=\"\" \/><\/p>\n<ul>\n<li>lock(\u9501\u5b9a)\uff1a\u4f5c\u7528\u4e8e\u4e3b\u5185\u5b58\u7684\u53d8\u91cf\uff0c\u628a\u4e00\u4e2a\u53d8\u91cf\u6807\u8bb0\u4e3a\u4e00\u6761\u7ebf\u7a0b\u72ec\u5360\u72b6\u6001<\/li>\n<li>unlock(\u89e3\u9501)\uff1a\u4f5c\u7528\u4e8e\u4e3b\u5185\u5b58\u7684\u53d8\u91cf\uff0c\u628a\u4e00\u4e2a\u5904\u4e8e\u9501\u5b9a\u72b6\u6001\u7684\u53d8\u91cf\u91ca\u653e\u51fa\u6765\uff0c\u91ca\u653e\u540e\u7684\u53d8\u91cf\u624d\u53ef\u4ee5\u88ab\u5176\u4ed6\u7ebf\u7a0b\u9501\u5b9a<\/li>\n<li>read(\u8bfb\u53d6)\uff1a\u4f5c\u7528\u4e8e\u4e3b\u5185\u5b58\u7684\u53d8\u91cf\uff0c\u628a\u4e00\u4e2a\u53d8\u91cf\u503c\u4ece\u4e3b\u5185\u5b58\u4f20\u8f93\u5230\u7ebf\u7a0b\u7684\u5de5\u4f5c\u5185\u5b58\u4e2d\uff0c\u4ee5\u4fbf\u968f\u540e\u7684load\u52a8\u4f5c\u4f7f\u7528<\/li>\n<li>load(\u8f7d\u5165)\uff1a\u4f5c\u7528\u4e8e\u5de5\u4f5c\u5185\u5b58\u7684\u53d8\u91cf\uff0c\u5b83\u628aread\u64cd\u4f5c\u4ece\u4e3b\u5185\u5b58\u4e2d\u5f97\u5230\u7684\u53d8\u91cf\u503c\u653e\u5165\u5de5\u4f5c\u5185\u5b58\u7684\u53d8\u91cf\u526f\u672c\u4e2d<\/li>\n<li>use(\u4f7f\u7528)\uff1a\u4f5c\u7528\u4e8e\u5de5\u4f5c\u5185\u5b58\u7684\u53d8\u91cf\uff0c\u628a\u5de5\u4f5c\u5185\u5b58\u4e2d\u7684\u4e00\u4e2a\u53d8\u91cf\u503c\u4f20\u9012\u7ed9\u6267\u884c\u5f15\u64ce<\/li>\n<li>assign(\u8d4b\u503c)\uff1a\u4f5c\u7528\u4e8e\u5de5\u4f5c\u5185\u5b58\u7684\u53d8\u91cf\uff0c\u5b83\u628a\u4e00\u4e2a\u4ece\u6267\u884c\u5f15\u64ce\u63a5\u6536\u5230\u7684\u503c\u8d4b\u7ed9\u5de5\u4f5c\u5185\u5b58\u7684\u53d8\u91cf<\/li>\n<li>store(\u5b58\u50a8)\uff1a\u4f5c\u7528\u4e8e\u5de5\u4f5c\u5185\u5b58\u7684\u53d8\u91cf\uff0c\u628a\u5de5\u4f5c\u5185\u5b58\u4e2d\u7684\u4e00\u4e2a\u53d8\u91cf\u7684\u503c\u4f20\u9001\u5230\u4e3b\u5185\u5b58\u4e2d\uff0c\u4ee5\u4fbf\u968f\u540e\u7684write\u7684\u64cd\u4f5c<\/li>\n<li>write(\u5199\u5165)\uff1a\u4f5c\u7528\u4e8e\u5de5\u4f5c\u5185\u5b58\u7684\u53d8\u91cf\uff0c\u5b83\u628astore\u64cd\u4f5c\u4ece\u5de5\u4f5c\u5185\u5b58\u4e2d\u7684\u4e00\u4e2a\u53d8\u91cf\u7684\u503c\u4f20\u9001\u5230\u4e3b\u5185\u5b58\u7684\u53d8\u91cf\u4e2d<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\u4ec0\u4e48\u662fJMM\u6a21\u578b Java\u5185\u5b58\u6a21\u578b(Java\u00a0Memory\u00a0Model\u7b80\u79f0JMM)\u662f\u4e00\u79cd\u62bd\u8c61\u7684\u6982\u5ff5\uff0c\u5e76\u4e0d\u771f\u5b9e\u5b58 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"_links":{"self":[{"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=\/wp\/v2\/posts\/151"}],"collection":[{"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=151"}],"version-history":[{"count":3,"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=\/wp\/v2\/posts\/151\/revisions"}],"predecessor-version":[{"id":195,"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=\/wp\/v2\/posts\/151\/revisions\/195"}],"wp:attachment":[{"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=151"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=151"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.isvmspace.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=151"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}