{"id":4066,"date":"2019-03-30T19:33:31","date_gmt":"2019-03-30T11:33:31","guid":{"rendered":"http:\/\/www.xttblog.com\/?p=4066"},"modified":"2019-03-30T19:33:31","modified_gmt":"2019-03-30T11:33:31","slug":"90%e7%9a%84%e7%a8%8b%e5%ba%8f%e5%91%98%e5%8f%af%e8%83%bd%e9%83%bd%e4%b8%8d%e4%ba%86%e8%a7%a3%e7%9a%84%e5%a0%86%e5%a4%96%e5%86%85%e5%ad%98","status":"publish","type":"post","link":"https:\/\/www.xttblog.com\/?p=4066","title":{"rendered":"90%\u7684\u7a0b\u5e8f\u5458\u53ef\u80fd\u90fd\u4e0d\u4e86\u89e3\u7684\u5806\u5916\u5185\u5b58"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">\u53bb\u5e74\u6211\u9762\u8bd5\u4e86\u4e00\u4e9b\u7a0b\u5e8f\u5458\uff0c\u7b49\u7ea7\u4ece\u4f4e\u5230\u9ad8\u90fd\u6709\u3002\u4f46\u662f\u6ca1\u6709\u4e00\u4e2a\u4eba\u80fd\u591f\u8bf4\u660e\u767d\u4ec0\u4e48\u662f\u5806\u5916\u5185\u5b58\uff01 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4eca\u5929\u6211\u4eec\u5c31\u4e00\u8d77\u6765\u7b80\u5355\u7684\u8bf4\u4e00\u8bf4 Java \u4e2d\u7684\u5806\u5916\u5185\u5b58\u3002\u8fd9\u4e00\u5757\u53ef\u80fd 90% \u7684 Java \u7a0b\u5e8f\u5458\u90fd\u4e0d\u6e05\u695a\uff0c\u5e0c\u671b\u4f60\u770b\u8fc7\u672c\u6587\u540e\uff0c\u6210\u4e3a\u90a3 10% \u4e2d\u7684\u5927\u795e\u7ea7\u522b\u7684\u6f5c\u529b\u80a1\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5806\u5916\u5185\u5b58\u662f\u76f8\u5bf9\u4e8e\u5806\u5185\u5185\u5b58\u7684\u4e00\u4e2a\u6982\u5ff5\u3002\u5806\u5185\u5185\u5b58\u662f\u7531 JVM \u6240\u7ba1\u63a7\u7684 Java \u8fdb\u7a0b\u5185\u5b58\uff0c\u6211\u4eec\u5e73\u65f6\u5728 Java \u4e2d\u521b\u5efa\u7684\u5bf9\u8c61\u90fd\u5904\u4e8e\u5806\u5185\u5185\u5b58\u4e2d\uff0c\u5e76\u4e14\u5b83\u4eec\u9075\u5faa JVM \u7684\u5185\u5b58\u7ba1\u7406\u673a\u5236\uff0cJVM \u4f1a\u91c7\u7528\u5783\u573e\u56de\u6536\u673a\u5236\u7edf\u4e00\u7ba1\u7406\u5b83\u4eec\u7684\u5185\u5b58\u3002\u90a3\u4e48\u5806\u5916\u5185\u5b58\u5c31\u662f\u5b58\u5728\u4e8e JVM \u7ba1\u63a7\u4e4b\u5916\u7684\u4e00\u5757\u5185\u5b58\u533a\u57df\uff0c\u56e0\u6b64\u5b83\u662f\u4e0d\u53d7 JVM \u7684\u7ba1\u63a7\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u73b0\u5b9e\u4e2d\u6709\u975e\u5e38\u591a\u7684\u6846\u67b6\u53ef\u80fd\u5c31\u4f7f\u7528\u4e86\u5806\u5916\u5185\u5b58\uff0c\u800c\u4e14\u8fd9\u4e9b\u6846\u67b6\u5f88\u53ef\u80fd\u4f60\u90fd\u4f7f\u7528\u8fc7\uff0c\u4f46\u662f\u4f60\u53ef\u80fd\u5e76\u4e0d\u4e86\u89e3\u5b83\u4eec\u662f\u5426\u6709\u4f7f\u7528\u8fc7\u5806\u5916\u5185\u5b58\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6bd4\u5982\uff1aEhcache \u4e2d\u7684\u4e00\u4e9b\u7248\u672c\uff0c\u5404\u79cd NIO \u6846\u67b6\uff0cDubbo\uff0cMemcache \u7b49\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728 Java \u4e2d\u6709\u51e0\u4e2a\u975e\u5e38\u91cd\u8981\u7684\u7c7b\uff0c\u6bd4\u5982\uff1aDirectByteBuffer\u3001ByteBuffer\u3001HeapByteBuffer\u7b49\u3002\u4f7f\u7528\u5b83\u4eec\u6211\u4eec\u53ef\u4ee5\u64cd\u4f5c\u5806\u5916\u5185\u5b58\u3002\u6bd4\u5982\u4e0b\u9762\u7684\u4ee3\u7801\uff1a <\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/**\n * @VM args:-XX:MaxDirectMemorySize=40m -verbose:gc -XX:+PrintGCDetails\n * -XX:+DisableExplicitGC \/\/\u589e\u52a0\u6b64\u53c2\u6570\u4e00\u4f1a\u513f\u5c31\u4f1a\u5185\u5b58\u6ea2\u51fa\n * java.lang.OutOfMemoryError: Direct buffer memory\n *\/\npublic static void TestDirectByteBuffer() {\n    List&lt;ByteBuffer&gt; list = new ArrayList&lt;ByteBuffer&gt;();\n    while(true) {\n        ByteBuffer buffer = ByteBuffer.allocateDirect(1 * 1024 * 1024);\n        \/\/list.add(buffer);\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u901a\u8fc7 ByteBuffer \u4f7f\u7528\u5806\u5916\u5185\u5b58\uff0c\u5c06\u5806\u5916\u5185\u5b58\u8bbe\u7f6e\u4e3a 40M\u3002DirectByteBuffer \u5173\u8054\u7684\u51e0\u4e2a\u7c7b\u7684\u7c7b\u56fe\u5982\u4e0b\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/images.weserv.nl\/?url=https:\/\/wx1.sinaimg.cn\/large\/8fa5dcfcgy1g1l1nu21fkj20b408aglz.jpg\" alt=\"\" \/><figcaption>Java\u64cd\u4f5c\u5806\u5916\u5185\u5b58<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">DirectByteBuffer \u8be5\u7c7b\u672c\u8eab\u8fd8\u662f\u4f4d\u4e8e Java \u5185\u5b58\u6a21\u578b\u7684\u5806\u4e2d\u3002\u5806\u5185\u5185\u5b58\u662f JVM \u53ef\u4ee5\u76f4\u63a5\u7ba1\u63a7\u3001\u64cd\u7eb5\u3002\u800c DirectByteBuffer \u4e2d\u7684 unsafe.allocateMemory(size); \u662f\u4e00\u4e2a native \u65b9\u6cd5\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u5206\u914d\u7684\u662f\u5806\u5916\u5185\u5b58\uff0c\u901a\u8fc7 C \u7684 malloc \u6765\u8fdb\u884c\u5206\u914d\u7684\u3002\u5206\u914d\u7684\u5185\u5b58\u662f\u7cfb\u7edf\u672c\u5730\u7684\u5185\u5b58\uff0c\u5e76\u4e0d\u5728 Java \u7684\u5185\u5b58\u4e2d\uff0c\u4e5f\u4e0d\u5c5e\u4e8e JVM \u7ba1\u63a7\u8303\u56f4\u3002\u90a3\u4e48\u65e2\u7136\u901a\u8fc7 DirectByteBuffer \u5206\u914d\u7684\u5806\u5916\u5185\u5b58\u4e0d\u53d7 JVM \u7ba1\u63a7\uff0c\u90a3\u4e48\u8fd9\u4e9b\u5185\u5b58\u8be5\u5982\u4f55\u56de\u6536\u5462\uff1f <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u548c\u6211\u516c\u4f17\u53f7\u4e0a\u4e00\u7bc7\u63a8\u6587\u300a<a href=\"https:\/\/mp.weixin.qq.com\/s\/bsPxOC7L3qnKN98LYAvySw\">\u624b\u628a\u624b\u6559\u4f60\u901a\u8fc7Java\u4ee3\u7801\u4f53\u9a8c\u5f3a\u5f15\u7528\u3001\u8f6f\u5f15\u7528\u3001\u5f31\u5f15\u7528\u3001\u865a\u5f15\u7528\u7684\u533a\u522b<\/a>\u300b\u7684\u5185\u5bb9\u5c31\u6709\u4e9b\u76f8\u5173\u6027\u4e86\u3002\u56e0\u4e3a DirectByteBuffer \u662f\u901a\u8fc7\u865a\u5f15\u7528(Phantom Reference)\u6765\u5b9e\u73b0\u5806\u5916\u5185\u5b58\u7684\u91ca\u653e\u7684\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">PhantomReference \u662f\u6240\u6709\u201c\u5f31\u5f15\u7528\u201d\u4e2d\u6700\u5f31\u7684\u5f15\u7528\u7c7b\u578b\u3002\u4e0d\u540c\u4e8e\u8f6f\u5f15\u7528\u548c\u5f31\u5f15\u7528\uff0c\u865a\u5f15\u7528\u65e0\u6cd5\u901a\u8fc7 get() \u65b9\u6cd5\u6765\u53d6\u5f97\u76ee\u6807\u5bf9\u8c61\u7684\u5f3a\u5f15\u7528\u4ece\u800c\u4f7f\u7528\u76ee\u6807\u5bf9\u8c61\uff0c\u89c2\u5bdf\u6e90\u7801\u53ef\u4ee5\u53d1\u73b0 get() \u88ab\u91cd\u5199\u4e3a\u6c38\u8fdc\u8fd4\u56de null\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u90a3\u865a\u5f15\u7528\u5230\u5e95\u6709\u4ec0\u4e48\u4f5c\u7528\uff1f\u5176\u5b9e\u865a\u5f15\u7528\u4e3b\u8981\u88ab\u7528\u6765\u8ddf\u8e2a\u5bf9\u8c61\u88ab\u5783\u573e\u56de\u6536\u7684\u72b6\u6001\uff0c\u901a\u8fc7\u67e5\u770b\u5f15\u7528\u961f\u5217\u4e2d\u662f\u5426\u5305\u542b\u5bf9\u8c61\u6240\u5bf9\u5e94\u7684\u865a\u5f15\u7528\u6765\u5224\u65ad\u5b83\u662f\u5426\u5373\u5c06\u88ab\u5783\u573e\u56de\u6536\uff0c\u4ece\u800c\u91c7\u53d6\u884c\u52a8\u3002\u5b83\u5e76\u4e0d\u88ab\u671f\u5f85\u7528\u6765\u53d6\u5f97\u76ee\u6807\u5bf9\u8c61\u7684\u5f15\u7528\uff0c\u800c\u76ee\u6807\u5bf9\u8c61\u88ab\u56de\u6536\u524d\uff0c\u5b83\u7684\u5f15\u7528\u4f1a\u88ab\u653e\u5165\u4e00\u4e2a ReferenceQueue \u5bf9\u8c61\u4e2d\uff0c\u4ece\u800c\u8fbe\u5230\u8ddf\u8e2a\u5bf9\u8c61\u5783\u573e\u56de\u6536\u7684\u4f5c\u7528\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3a\u4ec0\u4e48\u5f88\u591a\u9ad8\u6027\u80fd\u7684\u6846\u67b6\u4f1a\u4f7f\u7528\u5806\u5916\u5185\u5b58\u5462\uff1f\u5f88\u91cd\u8981\u7684\u4e00\u4e2a\u539f\u56e0\u5c31\u662f\u5b83\u4e0d\u53d7 JVM \u7ba1\u63a7\uff0c\u4e0d\u53d7 GC \u5f71\u54cd\u3002\u56e0\u6b64\u5806\u5916\u5185\u5b58\u7684\u4f18\u7f3a\u70b9\u53ef\u4ee5\u603b\u7ed3\u5982\u4e0b\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5806\u5916\u5185\u5b58\uff0c\u5176\u5b9e\u5c31\u662f\u4e0d\u53d7JVM\u63a7\u5236\u7684\u5185\u5b58\u3002\u76f8\u6bd4\u4e8e\u5806\u5185\u5185\u5b58\u6709\u51e0\u4e2a\u4f18\u52bf\uff1a <\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u51cf\u5c11\u4e86\u5783\u573e\u56de\u6536\u7684\u5de5\u4f5c\uff0c\u56e0\u4e3a\u5783\u573e\u56de\u6536\u4f1a\u6682\u505c\u5176\u4ed6\u7684\u5de5\u4f5c\uff08\u53ef\u80fd\u4f7f\u7528\u591a\u7ebf\u7a0b\u6216\u8005\u65f6\u95f4\u7247\u7684\u65b9\u5f0f\uff0c\u4f60\u6839\u672c\u611f\u89c9\u4e0d\u5230\uff09\u3002 <\/li><li>\u52a0\u5feb\u4e86\u590d\u5236\u7684\u901f\u5ea6\u3002\u56e0\u4e3a\u5806\u5185\u5728 flush \u5230\u8fdc\u7a0b\u65f6\uff0c\u4f1a\u5148\u590d\u5236\u5230\u76f4\u63a5\u5185\u5b58\uff08\u975e\u5806\u5185\u5b58\uff09\uff0c\u7136\u540e\u5728\u53d1\u9001\uff1b\u800c\u5806\u5916\u5185\u5b58\u76f8\u5f53\u4e8e\u7701\u7565\u6389\u4e86\u8fd9\u4e2a\u5de5\u4f5c\u3002 <\/li><li>\u53ef\u4ee5\u5728\u8fdb\u7a0b\u95f4\u5171\u4eab\uff0c\u51cf\u5c11 JVM \u95f4\u7684\u5bf9\u8c61\u590d\u5236\uff0c\u4f7f\u5f97 JVM \u7684\u5206\u5272\u90e8\u7f72\u66f4\u5bb9\u6613\u5b9e\u73b0\u3002 <\/li><li>\u53ef\u4ee5\u6269\u5c55\u81f3\u66f4\u5927\u7684\u5185\u5b58\u7a7a\u95f4\u3002\u6bd4\u5982\u8d85\u8fc7 1TB \u751a\u81f3\u6bd4\u4e3b\u5b58\u8fd8\u5927\u7684\u7a7a\u95f4\u3002 <\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u6709\u4f18\u70b9\u5c31\u6709\u7f3a\u70b9\uff0c\u7f3a\u70b9\u603b\u7ed3\u5982\u4e0b\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u5806\u5916\u5185\u5b58\u96be\u4ee5\u63a7\u5236\uff0c\u5982\u679c\u5185\u5b58\u6cc4\u6f0f\uff0c\u90a3\u4e48\u5f88\u96be\u6392\u67e5\u3002 <\/li><li>\u5806\u5916\u5185\u5b58\u76f8\u5bf9\u6765\u8bf4\uff0c\u4e0d\u9002\u5408\u5b58\u50a8\u5f88\u590d\u6742\u7684\u5bf9\u8c61\u3002\u4e00\u822c\u7b80\u5355\u7684\u5bf9\u8c61\u6216\u8005\u6241\u5e73\u5316\u7684\u6bd4\u8f83\u9002\u5408\u3002 <\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u7ad9\u5728\u7cfb\u7edf\u8bbe\u8ba1\u7684\u89d2\u5ea6\u6765\u770b\uff0c\u4f7f\u7528\u5806\u5916\u5185\u5b58\u53ef\u4ee5\u4e3a\u4f60\u7684\u8bbe\u8ba1\u63d0\u4f9b\u66f4\u591a\u53ef\u80fd\u3002\u6700\u91cd\u8981\u7684\u63d0\u5347\u5e76\u4e0d\u5728\u4e8e\u6027\u80fd\uff0c\u800c\u662f\u51b3\u5b9a\u6027\u7684\u3002 <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5173\u4e8e\u5806\u5916\u5185\u5b58\u8fd9\u4e00\u5757\uff0c\u4f60\u5728\u9762\u8bd5 Dubbo \u6216\u8005 Netty \u7b49\u6846\u67b6\u7684\u65f6\u5019\uff0c\u53ef\u80fd\u5c31\u4f1a\u9047\u5230\u3002\u6df1\u5165\u6e90\u7801\u5374\u7406\u89e3\u5b83\u4eec\uff0c\u4f1a\u6709\u4e0d\u4e00\u6837\u7684\u53d1\u73b0\u3002\u540e\u9762\u4f1a\u6709\u76f8\u5173\u7684\u8111\u56fe\u5206\u4eab\uff0c\u5177\u4f53\u770b 4 \u6708\u4efd\u7684\u65f6\u95f4\u5b89\u6392\u5427\u3002 <\/p>\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 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