{"id":4937,"date":"2020-03-27T18:33:41","date_gmt":"2020-03-27T10:33:41","guid":{"rendered":"https:\/\/www.xttblog.com\/?p=4937"},"modified":"2020-03-27T18:33:41","modified_gmt":"2020-03-27T10:33:41","slug":"%e4%b8%80%e6%ac%a1%e9%98%bf%e9%87%8c-p8-%e7%9a%84%e9%97%ae%e7%ad%94%e4%ba%a4%e8%b0%88%e4%b9%8b%e6%97%85%ef%bc%81","status":"publish","type":"post","link":"https:\/\/www.xttblog.com\/?p=4937","title":{"rendered":"\u4e00\u6b21\u963f\u91cc P8 \u7684\u95ee\u7b54\u4ea4\u8c08\u4e4b\u65c5\uff01"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u8bf7\u6559\u4e00\u4e2a\u95ee\u9898\uff0c\u5728\u5c40\u57df\u7f51\u5185\u5bf9\u4e00\u53f0\u7070\u5ea6\u673a\u5668\u8fdb\u884c\u538b\u6d4b\uff0c\u5982\u679c\u5e26\u5bbd\u88ab\u6253\u6ee1\u540e\uff0c\u538b\u6d4b\u7684\u6548\u679c\u4e5f\u5c31\u5230\u74f6\u9888\u4e86\uff0c\u90a3\u4e48\u95ee\u9898\u6765\u4e86\uff0c\u600e\u4e48\u5224\u65ad\u8fd9\u53f0\u7070\u5ea6\u673a\u5668\u7684\u5e26\u5bbd\u662f\u5426\u88ab\u6253\u6ee1\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6211\uff1a\u6709\u51e0\u4e2a\u5de5\u5177\u90fd\u53ef\u4ee5\u770b iftop\uff08\u795e\u5668\uff09\u3001dstat\u3001sar \u90fd\u53ef\u4ee5\u770b\u3002<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u6211\u4eec\u5e38\u8bf4\u7684\u7f51\u901f\u662f\u6309\u7167 bit 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\u662f\u4e00\u4e2a\u5fc5\u4fee\u8bfe\u3002\u5938\u5f20\u4e00\u70b9\u8bf4\uff0c\u7406\u89e3\u4e86 OSGI \u7684\u6574\u5957\u6280\u672f\u4f53\u7cfb\uff0c\u65e5\u540e\u518d\u78b0\u5230 classloader \u76f8\u5173\u95ee\u9898\u65f6\u4f1a\u611f\u89c9\u6709\u4e9b\u723d\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u5982\u679c\u6211\u5199\u4e86\u4e00\u4e2a\u5c0f\u63d2\u4ef6\uff08\u7c7b\u4f3c fastjson \uff09\u8fd9\u79cd\u5de5\u5177\u7c7b\u3002\u600e\u4e48\u53bb\u5224\u65ad\u5b83\u6027\u80fd\u662f\u4e0d\u662f\u6ee1\u8db3\u8981\u6c42\u5462\uff1f\u770b\u5185\u5b58\u5806\u5360\u7528\u7684\u7a7a\u95f4\u6216\u8005\u8fd8\u662f\u5176\u5b83\u7684\u53c2\u8003\u91cf\uff1f\u8c22\u8c22\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u6bcf\u4e2a\u7ec4\u4ef6\u90fd\u6709\u5176\u5173\u6ce8\u7684\u6838\u5fc3\u76ee\u6807\uff0c\u5982\u679c\u662f\u4e00\u4e2a\u5ba2\u6237\u7aef\u5e93\uff0c\u9700\u8981\u8003\u91cf\u7684\u70b9\u662f\u6bcf\u6b21\u65b9\u6cd5\u8c03\u7528\u7684\u6267\u884c\u65f6\u95f4\uff08\u8d8a\u9ad8\u8d8a\u597d\uff09\u3001\u4f7f\u7528\u65f6\u5185\u5b58\u5360\u7528\uff08\u8d8a\u4f4e\u8d8a\u597d\uff09\u548c\u56e0\u4e3a\u672c\u7ec4\u4ef6\u5f15\u8d77\u7684GC\u6570\uff08\u8d8a\u5c11\u8d8a\u597d\uff09\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u7ebf\u4e0a CPU \u5f88\u9ad8\u3001\u5185\u5b58\u5360\u7528\u5f88\u5c11\uff0c\u6709\u80fd\u5feb\u901f\u67e5\u627e\u5230\u539f\u56e0\u7684\u65b9\u6cd5\u5417\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u7ed9\u4e00\u4e2a\u4ee3\u7801\uff0c\u5728 Linux \u4e0b\u4fdd\u5b58\u6210 .sh \u6587\u4ef6\u76f4\u63a5\u6267\u884c\u5373\u53ef\u3002<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\"><code>#!\/bin\/sh<\/code><code>ts=$(date +\"%s\")<\/code><code>jvmPid=$1<\/code><code>defaultLines=100<\/code><code>defaultTop=20<\/code><code>threadStackLines=${2:-$defaultLines}<\/code><code>topThreads=${3:-$defaultTop}<\/code><code>jvmCapture=$(top -b -n1 | grep java )<\/code><code>threadsTopCapture=$(top -b -n1 -H | grep java )<\/code><code>jstackOutput=$(echo \"$(jstack $jvmPid )\" )<\/code><code>topOutput=$(echo \"$(echo \"$threadsTopCapture\" | head -n $topThreads | perl -pe 's\/\\e\\[?.*?[\\@-~] ?\/\/g' | awk '{gsub(\/^ +\/,\"\");print}' | awk '{gsub(\/ +|[+-]\/,\" \");print}' | cut -d \" \" -f 1,9 )\\n \")<\/code><code>echo \"*************************************************************************************************************\"<\/code><code>uptime<\/code><code>echo \"Analyzing top $topThreads threads\"<\/code><code>echo \"*************************************************************************************************************\"<\/code><code>printf %s \"$topOutput\" | while IFS= read  line<\/code><code>do<\/code><code>   pid=$(echo $line | cut -d \" \" -f 1)<\/code><code>   hexapid=$(printf \"%x\" $pid)<\/code><code>   cpu=$(echo $line | cut -d \" \" -f 2)<\/code><code>   echo -n $cpu\"% [$pid] \" <\/code><code>   echo \"$jstackOutput\" | grep \"tid.*0x$hexapid \" -A $threadStackLines | sed -n -e '\/0x'$hexapid'\/,\/tid\/ p' | head -n -1<\/code><code>   echo \"\\n\"<\/code><code>done<\/code><code>echo \"\\n\" <\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4ee3\u7801\u7684\u610f\u601d\uff0c\u6253\u5370\u51fa JVM \u7684\u6240\u6709\u7ebf\u7a0b\u4ee5\u53ca\u6309\u7167 CPU \u5360\u6bd4\u6392\u5e8f\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u4e3a\u4ec0\u4e48 Java 8 \u91cd\u5199\u4e86 ConcurrentHashMap\uff1f\u57fa\u4e8e\u4ec0\u4e48\u7684\u8003\u8651\uff1f\u4f18\u5316\u4e86\u4ec0\u4e48\u7279\u6027\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u4e3a\u4e86\u83b7\u5f97\u66f4\u597d\u7684\u6027\u80fd\uff0c1.8 \u7684 ConcurrentHashMap \u5728\u539f\u6765\u7684\u57fa\u7840\u4e0a\u6027\u80fd\u505a\u4e86\u6539\u8fdb\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>table \u6bcf\u4e2a\u5143\u7d20\u4f5c\u4e3a\u4e00\u4e2a\u6876\uff0c\u9501\u7684\u7c92\u5ea6\u66f4\u7ec6\uff0c\u7528 synchronized \u5173\u952e\u5b57\u9501\u4f4f table[i]\u3002<\/li><li>\u52a0\u5165\u7ea2\u9ed1\u6811\uff0c\u5f53\u94fe\u8868\u7684\u6570\u91cf\u8d85\u8fc78\u5e76\u4e14\u5f53\u524d capacity \u5927\u4e8e 64 \u65f6\u5019\uff0c\u5c06\u94fe\u8868\u8f6c\u4e3a\u7ea2\u9ed1\u6811\uff0c\u65f6\u95f4\u590d\u6742\u5ea6 O(N)\u2192O(logN)\uff0c\u5e76\u4e14\u7ea2\u9ed1\u6811\u4e2d\u5229\u7528\u8bfb\u5199\u9501\u4fdd\u8bc1\u6dfb\u52a0\u4fee\u590d\u548c\u5220\u9664\u4fee\u590d\u65f6\u5019\u7684\u7ebf\u7a0b\u5b89\u5168\u3002<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u53e6\u5916\uff0c\u5173\u4e8e ConcurrentHashMap \u5728 1.8 \u4e2d\uff0c\u9664\u4e86\u505a\u4e86\u6269\u5bb9\u65f6\u7684\u4f18\u5316\u4ee5\u5916\uff0c\u4e5f\u53bb\u9664\u4e86\u5206\u6bb5\u9501\uff0c\u539f\u56e0\u662f\u5206\u6bb5\u9501\u7684\u5728\u6269\u5145\u5e76\u53d1\u5ea6\u4ee5\u53ca\u6574\u4e2a map \u5bb9\u91cf\u6269\u5c55\u65f6\u9700\u8981\u9501\u4f4f\u6240\u6709\u7684\u6bb5\u3002\u6240\u4ee5\uff0c1.8 \u4e2d\u5bf9 ConcurrentHashMap \u505a\u4e86\u66f4\u7ec6\u7c92\u5ea6\u7684\u4f18\u5316\uff0c\u53ea\u5728 put\u3001resize \u4ee5\u53ca\u6269\u5bb9\u662f\u52a0\u9501\uff0c\u6765\u505a\u4f18\u5316\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u5982\u679c\u7528\u5fae\u670d\u52a1\u601d\u60f3\u5f00\u53d1\uff0cDubbo \u548c Spring cloud \u90a3\u4e2a\u66f4\u597d\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1aDubbo \u548c Spring cloud \u4e0d\u662f\u4e00\u4e2a\u5c42\u9762\u4e0a\uff0c\u5982\u679c\u8981\u505a\u5fae\u670d\u52a1\u8bbe\u8ba1\uff0c\u5fc5\u7136\u4f1a\u6709\u7cfb\u7edf\u95f4\u4ea4\u4e92\uff0cRPC \u662f\u7cfb\u7edf\u95f4\u4ea4\u4e92\u7684\u4e00\u79cd\uff0c\u670d\u52a1\u6cbb\u7406\u4e5f\u662f\u5fae\u670d\u52a1\u7684\u4e00\u4e2a\u5fc5\u9700\u5b50\u96c6\uff0c\u4f46\u662f\u5fae\u670d\u52a1\u8fd8\u5305\u62ec\u5176\u5b83\u7684\u4e1c\u897f\u3002\u800c Spring Cloud \u662f\u5fae\u670d\u52a1\u7684\u4e00\u79cd\u5b9e\u73b0\uff0c\u5176\u5305\u542b\u7684\u529f\u80fd\u8981\u591a\u4e8e Dubbo\u3002<\/p>\n\n\n\n<p 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class=\"wp-block-paragraph\">\u7b54\uff1a\u591a\u91cd\u7ee7\u627f\u4e00\u822c\u4f1a\u5f15\u5165\u5f88\u591a\u9ebb\u70e6\uff0c\u6bd4\u5982\u7c7b\u5173\u7cfb\u590d\u6742\u3001\u5c42\u7ea7\u8fc7\u957f\u7b49\uff0c\u4e00\u822c\u8bed\u8a00\u4e2d\u90fd\u662f\u4f7f\u7528\u53d7\u9650\u5236\u7684\u591a\u91cd\u7ee7\u627f\u3002\u5bf9\u6bd4\u591a\u79cd\u8bed\u8a00\u6765\u770b\uff0cJava \u662f implement \u591a\u4e2a\u63a5\u53e3\uff0c\u8fd9\u79cd\u53ef\u4ee5\u8ba4\u4e3a\u662f\u7ee7\u627f\u89c4\u8303\uff08\u5b9a\u4e49\uff09\uff0c\u7136\u540e\u4f1a\u7528\u7ec4\u5408\u6a21\u5f0f\u6765\u5b8c\u6210\u7c7b\u4f3c\u591a\u91cd\u7ee7\u627f\u3002Python \u662f mixin \u7ee7\u627f\u6a21\u5f0f\uff0c\u662f\u4ee3\u7801\u7ee7\u627f\uff08\u6709\u4e00\u5b9a\u8981\u6c42\uff09\uff0c\u8be6\u7ec6\u5bf9\u6bd4\u5efa\u8bae Google \u6216\u8005\u77e5\u4e4e\u4e86\u89e3\u4e0b mixin\u3001MRO Python\uff0c\u591a\u91cd\u7ee7\u627f\u8fd9\u51e0\u4e2a\u5173\u952e\u8bcd\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u7ebf\u4e0a\u5b9a\u4f4d\u5185\u5b58 JVM \u5185\u5b58\u6ea2\u51fa\uff0c\u9664\u4e86\u6253\u5370\u5806\u6808\u62ff\u51fa\u6765\u5206\u6790\uff0c\u8fd8\u6709\u6ca1\u6709\u5176\u5b83\u7684\u65b9\u5f0f\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u5bfc\u51fa JVM dump \u6587\u4ef6\uff0c\u5728\u672c\u5730\u4f7f\u7528 Eclipse \u63d2\u4ef6 MAT \u5206\u6790\uff0c\u53ef\u89c6\u5316\u7684\u5206\u6790\u6700\u65b9\u4fbf\u3001\u76f4\u89c2\u3001\u6709\u6548\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1aThreadLocal \u5728\u4f7f\u7528\u4e0a\u6709\u4ec0\u4e48\u9700\u8981\u6ce8\u610f\u7684\uff1f\u5728\u9ad8\u5e76\u53d1\u8bf7\u6c42\u7684\u73af\u5883\u4e0b\u6027\u80fd\u5982\u4f55\uff1f\u4f1a\u6709\u4ec0\u4e48\u95ee\u9898\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a \u6ce8\u610f\u4e8b\u9879\uff0c\u4f7f\u7528\u7ed3\u675f\u4ee5\u540e\u8fdb\u884c remove \u64cd\u4f5c\uff0c\u907f\u514d ThreadLocal \u5bf9\u8c61\u8d8a\u6765\u8d8a\u5927\u3002\u9ad8\u5e76\u53d1\u7684\u573a\u666f\uff0c\u7531\u4e8e ThreadLocal \u5185\u90e8\u4f7f\u7528 HashMap \u7684\u539f\u7406\uff0ckey = currentThread\uff0c\u56e0\u4e3a HashMap \u662f\u975e\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u4e00\u5b9a\u8981\u6ce8\u610f hashmap.resize \u7684\u65f6\u5019\uff0c\u53ef\u80fd\u4f1a\u5bfc\u81f4\u67d0\u51e0\u4e2a CPU 100% \u7684\u95ee\u9898\uff0c\u8fdb\u800c\u5bfc\u81f4\u5e94\u7528\u51fa\u73b0\u8d44\u6e90\u8017\u5c3d\u7b49\u4e0d\u53ef\u9884\u77e5\u7684\u95ee\u9898\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u5047\u8bbe\u73b0\u5728\u6709\u4e00\u4e2a\u5de5\u4f5c\u4e86\u4e09\u5e74\u7684 Java \u5de5\u7a0b\u5e08\uff0c\u60f3\u505a\u5230\u6280\u672f\u4e13\u5bb6\u4f60\u8ba4\u4e3a\u5e94\u8be5\u5177\u5907\u4ec0\u4e48\u6837\u7684\u80fd\u529b\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u7f16\u7801\u5b9e\u8df5\uff0c\u4f8b\u5982\u575a\u6301\u5728 GitHub \u4e0a\u5199\u4e00\u4e9b\u4e3a\u4e86\u5e94\u7528\u6280\u672f\u800c\u5e94\u7528\u7684 example\u3002\u8bfb\u4ed6\u4eba\u4ee3\u7801\uff0c\u5404\u79cd\u5f00\u6e90\u6846\u67b6\u7684\u6e90\u7801\u3002\u591a\u8bfb\u4e66\uff0c\u591a\u770b Importnew\u3001InfoQ\u3001www.xttblog.com \u4e4b\u7c7b\u7684\u6587\u7ae0\uff0c\u591a\u95ee\uff0c\u770b\u5230\u76f8\u4f3c\u70b9\u65f6\u56de\u8fc7\u53bb\u770b\u770b\u81ea\u5df1\u505a\u7684\u662f\u5426\u8fd8\u6709\u6539\u8fdb\u7684\u7a7a\u95f4\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u514b\u9686\u5bf9\u8c61\u65f6\uff0c\u4e3a\u4ec0\u4e48\u8981\u5728\u5bf9\u8c61\u4e2d\u91cd\u5199\u4e00\u4e2a public \u7c7b\u578b\u7684 clone() \u65b9\u6cd5\u5462\uff1fObject \u7c7b\u4e2d\u6709\u4e00\u4e2a protected \u7c7b\u578b\u7684 clone() \u65b9\u6cd5\uff0c\u4f46\u662f\u8981\u514b\u9686\u7684\u5bf9\u8c61\u662f Object \u7c7b\u7684\u5b50\u7c7b\u554a\uff0c\u5728\u4e0d\u540c\u5305\u4e0b\u5e76\u5b58\u5728\u7ee7\u627f\u5173\u7cfb\u7684\u6761\u4ef6\u4e0b\u5e94\u8be5\u53ef\u4ee5\u8bbf\u95ee Object \u7684 protected \u65b9\u6cd5\u554a\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u9996\u5148 Java \u7684 clone \u662f\u8bbe\u8ba1\u6a21\u5f0f\u4e2d\u539f\u578b\u6a21\u5f0f\u7684\u4e00\u4e2a\u5178\u578b\u5e94\u7528\uff0c\u514b\u9686\u5206\u6d45\u62f7\u8d1d\u548c\u6df1\u62f7\u8d1d\uff0c\u4e8c\u8005\u7684\u533a\u522b\u81ea\u884c\u641c\u7d22\u3002Object.clone() \u662f\u6d45\u62f7\u8d1d\uff0c\u4e00\u822c\u590d\u6742\u5bf9\u8c61\u7684 clone \u6700\u597d\u4f7f\u7528\u6df1\u62f7\u8d1d\uff0c\u6240\u4ee5\u9700\u8981\u91cd\u5199 clone \u65b9\u6cd5\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1aJVM\uff08\u57fa\u4e8eJDK 1.8\uff09\u5728\u6267\u884c\u5783\u573e\u56de\u6536\u7684\u65f6\u5019\uff0c\u5bf9\u4e8e\u5806\u533a\u5e74\u8f7b\u4ee3\u5185\u5b58\u533a\u57df\u56de\u6536\u8f83\u9891\u7e41\uff0c\u8bf7\u95ee\u5982\u4f55\u66f4\u597d\u7684\u63a7\u5236 JVM \u6267\u884c\u56de\u6536\u7684\u8282\u594f\uff1f \u53e6\u5916\uff0c\u5982\u679c\u5408\u7406\u5730\u63a7\u5236\u597d\u5e74\u8f7b\u4ee3\u548c\u5e74\u8001\u4ee3\u7684\u5360\u6bd4\u4ee5\u53ca\u5e74\u8f7b\u4ee3\u91cc\u9762\u7684 eden \u533a\u548c\u4e24\u4e2a\u5e78\u5b58\u533a\u7684\u5360\u6bd4\uff0c\u80fd\u5f88\u597d\u7684\u8fbe\u5230\u5783\u573e\u56de\u6536\u6548\u679c\uff0c\u8bf7\u95ee\u4e0b\uff0c\u5982\u4f55\u5408\u7406\u7684\u63a7\u5236\u5806\u533a\u7684\u5e74\u8001\u4ee3\u548c\u5e74\u8f7b\u4ee3\u7684\u5185\u5b58\u5206\u914d\u5360\u6bd4\uff1f\u8fd8\u6709\u5982\u4f55\u66f4\u597d\u5730\u63a7\u5236\u5e74\u8f7b\u4ee3\u4e2d\uff0ceden \u533a\u548c\u4e24\u4e2a\u5e78\u5b58\u533a\u7684\u5360\u6bd4\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u5e74\u8f7b\u4ee3\u5927\u5c0f\u9009\u62e9\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u54cd\u5e94\u65f6\u95f4\u4f18\u5148\u7684\u5e94\u7528\uff1a\u5c3d\u53ef\u80fd\u8bbe\u7f6e\u5927\uff0c\u76f4\u5230\u63a5\u8fd1\u7cfb\u7edf\u7684\u6700\u4f4e\u54cd\u5e94\u65f6\u95f4\u9650\u5236\uff08\u6839\u636e\u5b9e\u9645\u60c5\u51b5\u9009\u62e9\uff09\u3002\u5728\u6b64\u79cd\u60c5\u51b5\u4e0b\uff0c\u5e74\u8f7b\u4ee3\u6536\u96c6\u53d1\u751f\u7684\u9891\u7387\u4e5f\u662f\u6700\u5c0f\u7684\u3002\u540c\u65f6\uff0c\u51cf\u5c11\u5230\u8fbe\u5e74\u8001\u4ee3\u7684\u5bf9\u8c61\u3002<\/li><li>\u541e\u5410\u91cf\u4f18\u5148\u7684\u5e94\u7528\uff1a\u5c3d\u53ef\u80fd\u8bbe\u7f6e\u5927\uff0c\u53ef\u80fd\u5230\u8fbe Gbit \u7684\u7a0b\u5ea6\u3002\u56e0\u4e3a\u5bf9\u54cd\u5e94\u65f6\u95f4\u6ca1\u6709\u8981\u6c42\uff0c\u5783\u573e\u6536\u96c6\u53ef\u4ee5\u5e76\u884c\u8fdb\u884c\uff0c\u4e00\u822c\u9002\u5408 8 CPU \u4ee5\u4e0a\u7684\u5e94\u7528\u3002<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u5e74\u8001\u4ee3\u5927\u5c0f\u9009\u62e9\u3002\u54cd\u5e94\u65f6\u95f4\u4f18\u5148\u7684\u5e94\u7528\uff1a\u5e74\u8001\u4ee3\u4f7f\u7528\u5e76\u53d1\u6536\u96c6\u5668\uff0c\u6240\u4ee5\u5176\u5927\u5c0f\u9700\u8981\u5c0f\u5fc3\u8bbe\u7f6e\uff0c\u4e00\u822c\u8981\u8003\u8651\u5e76\u53d1\u4f1a\u8bdd\u7387\u548c\u4f1a\u8bdd\u6301\u7eed\u65f6\u95f4\u7b49\u4e00\u4e9b\u53c2\u6570\u3002\u5982\u679c\u5806\u8bbe\u7f6e\u5c0f\u4e86\uff0c\u53ef\u4ee5\u4f1a\u9020\u6210\u5185\u5b58\u788e\u7247\u3001\u9ad8\u56de\u6536\u9891\u7387\u4ee5\u53ca\u5e94\u7528\u6682\u505c\u800c\u4f7f\u7528\u4f20\u7edf\u7684\u6807\u8bb0\u6e05\u9664\u65b9\u5f0f\uff1b\u5982\u679c\u5806\u5927\u4e86\uff0c\u5219\u9700\u8981\u8f83\u957f\u7684\u6536\u96c6\u65f6\u95f4\u3002\u6700\u4f18\u5316\u7684\u65b9\u6848\uff0c\u4e00\u822c\u9700\u8981\u53c2\u8003\u4ee5\u4e0b\u6570\u636e\u83b7\u5f97\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u5e76\u53d1\u5783\u573e\u6536\u96c6\u4fe1\u606f<\/li><li>\u6301\u4e45\u4ee3\u5e76\u53d1\u6536\u96c6\u6b21\u6570<\/li><li>\u4f20\u7edf GC \u4fe1\u606f<\/li><li>\u82b1\u5728\u5e74\u8f7b\u4ee3\u548c\u5e74\u8001\u4ee3\u56de\u6536\u4e0a\u7684\u65f6\u95f4\u6bd4\u4f8b<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u51cf\u5c11\u5e74\u8f7b\u4ee3\u548c\u5e74\u8001\u4ee3\u82b1\u8d39\u7684\u65f6\u95f4\uff0c\u4e00\u822c\u4f1a\u63d0\u9ad8\u5e94\u7528\u7684\u6548\u7387\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u5982\u4f55\u907f\u5f00\u6cdb\u578b\u7c7b\u578b\u64e6\u9664\u5e26\u6765\u7684\u9650\u5236\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u4e2a\u4eba\u89c9\u5f97\u6362\u4e2a\u4e0d\u4f1a\u6cdb\u578b\u64e6\u9664\u7684\u8bed\u8a00\uff0c\u5982 C#\uff0c\u8981\u4e0d\u6362\u5176\u4ed6\u5f31\u7c7b\u578b\u8bed\u8a00\u6216\u8005 Kotlin \u8fd9\u79cd\uff0c\u53ef\u4ee5\u7f16\u8bd1\u671f\u63a8\u5bfc\u51fa\u7c7b\u578b\u7684\u8bed\u8a00\u3002Java \u7684\u8bdd\u53ea\u80fd\u5f00\u53d1\u65f6\u591a\u6ce8\u610f\u4e86\u3002<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\"><code>public static void main(String[] args) {<\/code><code>   List&lt;Integer&gt; intList = new ArrayList&lt;&gt;();<\/code><code>   intList.add(1);<\/code><code>   try {<\/code><code>       Method method = intList.getClass().getDeclaredMethod(\"add\", Object.class);<\/code><code>       try {<\/code><code>           method.invoke(intList, \"string1\");<\/code><code>           method.invoke(intList, 0.5f);<\/code><code>       } catch (IllegalAccessException e) {<\/code><code>           e.printStackTrace();<\/code><code>       } catch (InvocationTargetException e) {<\/code><code>           e.printStackTrace();<\/code><code>       }<\/code><code>   } catch (NoSuchMethodException e) {<\/code><code>       e.printStackTrace();<\/code><code>   }<\/code><code>   for (Object i : intList) {<\/code><code>       System.out.println(i.toString());<\/code><code>   }<\/code><code>}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1aJVM \u5982\u4f55\u8fdb\u9636\uff0c\u76ee\u524d\u5468\u5fd7\u660e\u7684\u300a\u6df1\u5165\u7406\u89e3 JVM\u300b\u7b2c2\u7248\u770b\u4e86\u4e24\u904d\uff0c\u80fd\u591f\u6839\u636e\u76ee\u5f55\u53e3\u8ff0\u4e66\u4e2d\u5927\u90e8\u5206\u5185\u5bb9\uff0c\u8fd8\u9700\u8981\u4e86\u89e3\u54ea\u4e9b\u77e5\u8bc6\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u5468\u5fd7\u660e\u7684\u4e66\u53ea\u80fd\u7b97\u662f JVM \u7684\u5165\u95e8\u4e66\u7c4d\u3002\u63a5\u4e0b\u6765\u4f60\u5e94\u8be5\u53bb\u8bfb\u4e00\u8bfb\u300aJava \u865a\u62df\u673a\u89c4\u8303\u300b\uff0c\u5468\u5fd7\u660e\u7684\u4e66\u5f88\u591a\u5185\u5bb9\u662f\u4ece\u91cc\u9762\u6765\u7684\uff0c\u4f46\u662f\u89c4\u8303\u672c\u8eab\u6bd4\u8f83\u8be6\u7ec6\uff0c\u6ce8\u610f\u8bfb\u82f1\u6587\u539f\u7248\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5176\u6b21\u53bb\u8bfb\u4e00\u4e0b Oralce \u7684\u6587\u6863\uff1a\u300aHotspot Memory Management white paper\u300b, \u300aJava Platform, Standard Edition HotSpot Virtual Machine Garbage Collection Tuning Guide\u300b\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u73b0\u5728\u4f60\u9700\u8981\u8fdb\u4e00\u6b65\u4fee\u70bc\u5173\u4e8e\u5185\u5b58\u7ba1\u7406\u7684\u90e8\u5206\uff0c\u9605\u8bfb\u6bd4\u5982\u300a\u5783\u573e\u56de\u6536\u7b97\u6cd5\u4e0e\u5b9e\u73b0\u300b\uff0c\u5982\u679c\u8fd9\u672c\u8bfb\u5b8c\u8fd8\u4e0d\u6ee1\u8db3\uff0c\u90a3\u4e48\u9605\u8bfb\u300a\u81ea\u52a8\u5185\u5b58\u7ba1\u7406\u827a\u672f\u2014\u2014\u5783\u573e\u56de\u6536\u7b97\u6cd5\u624b\u518c\u300b\u3002\u5230\u4e86\u8fd9\u4e00\u6b65\uff0c\u7406\u8bba\u4f60\u5df2\u7ecf\u638c\u63e1\u5f97\u5f88\u597d\u4e86\uff0c\u662f\u65f6\u5019\u628a Hotspot \u6e90\u7801 download \u4e0b\u6765\u7f16\u8bd1\u597d\u4e4b\u540e\u65ad\u70b9\u8c03\u8bd5\u73a9\u73a9\u4e86\uff0c\u8fd9\u4e2a\u65f6\u5019\u6211\u8981\u63a8\u8350\u4f60\u4eca\u5e74\u963f\u91cc\u4eba\u521a\u51fa\u7684\u300a\u63ed\u79d8Java\u865a\u62df\u673a\u300b\uff0c\u4e0d\u8fc7\u9605\u8bfb\u8fd9\u672c\u4e66\u4e4b\u524d\u4f60\u8981\u662f\u613f\u610f\u5148\u8bfb\u5b8c\u300a\u6df1\u5165\u7406\u89e3\u8ba1\u7b97\u673a\u7cfb\u7edf\u300b\u6548\u679c\u66f4\u597d\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u5982\u4f55\u66f4\u597d\u7684\u4f7f\u7528\u591a\u7ebf\u7a0b\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u2460 \u9ad8\u5e76\u53d1\u3001\u4efb\u52a1\u6267\u884c\u65f6\u95f4\u77ed\u7684\u4e1a\u52a1\uff0c\u7ebf\u7a0b\u6c60\u7ebf\u7a0b\u6570\u53ef\u4ee5\u8bbe\u7f6e\u4e3aCPU\u6838\u6570+1\uff0c\u51cf\u5c11\u7ebf\u7a0b\u4e0a\u4e0b\u6587\u7684\u5207\u6362\u3002\n\u2461 \u5e76\u53d1\u4e0d\u9ad8\u3001\u4efb\u52a1\u6267\u884c\u65f6\u95f4\u957f\u7684\u4e1a\u52a1\u8981\u533a\u5206\u5f00\u770b\uff1a\u3000\u3000<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u5047\u5982\u662f\u4e1a\u52a1\u65f6\u95f4\u957f\u96c6\u4e2d\u5728 I\/O \u64cd\u4f5c\u4e0a\uff0c\u4e5f\u5c31\u662f I\/O \u5bc6\u96c6\u578b\u7684\u4efb\u52a1\uff0c\u56e0\u4e3a I\/O \u64cd\u4f5c\u5e76\u4e0d\u5360\u7528 CPU\uff0c\u6240\u4ee5\u4e0d\u8981\u8ba9\u6240\u6709\u7684 CPU \u95f2\u4e0b\u6765\uff0c\u53ef\u4ee5\u52a0\u5927\u7ebf\u7a0b\u6c60\u4e2d\u7684\u7ebf\u7a0b\u6570\u76ee\uff0c\u8ba9 CPU \u5904\u7406\u66f4\u591a\u7684\u4e1a\u52a1\u3002\u3000\u3000<\/li><li>\u5047\u5982\u662f\u4e1a\u52a1\u65f6\u95f4\u957f\u96c6\u4e2d\u5728\u8ba1\u7b97\u64cd\u4f5c\u4e0a\uff0c\u4e5f\u5c31\u662f\u8ba1\u7b97\u5bc6\u96c6\u578b\u4efb\u52a1\uff0c\u8fd9\u4e2a\u5c31\u6ca1\u529e\u6cd5\u4e86\uff0c\u548c\u2460\u4e00\u6837\u5427\uff0c\u7ebf\u7a0b\u6c60\u4e2d\u7684\u7ebf\u7a0b\u6570\u8bbe\u7f6e\u5f97\u5c11\u4e00\u4e9b\uff0c\u51cf\u5c11\u7ebf\u7a0b\u4e0a\u4e0b\u6587\u7684\u5207\u6362\u3002<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u2462 \u5e76\u53d1\u9ad8\u3001\u4e1a\u52a1\u6267\u884c\u65f6\u95f4\u957f\uff0c\u89e3\u51b3\u8fd9\u79cd\u7c7b\u578b\u4efb\u52a1\u7684\u5173\u952e\u4e0d\u5728\u4e8e\u7ebf\u7a0b\u6c60\u800c\u5728\u4e8e\u6574\u4f53\u67b6\u6784\u7684\u8bbe\u8ba1\uff0c\u770b\u770b\u8fd9\u4e9b\u4e1a\u52a1\u91cc\u9762\u67d0\u4e9b\u6570\u636e\u662f\u5426\u80fd\u505a\u7f13\u5b58\u662f\u7b2c\u4e00\u6b65\uff0c\u589e\u52a0\u670d\u52a1\u5668\u662f\u7b2c\u4e8c\u6b65\uff0c\u81f3\u4e8e\u7ebf\u7a0b\u6c60\u7684\u8bbe\u7f6e\uff0c\u8bbe\u7f6e\u53c2\u8003 \u2461\u3002\n\u6700\u540e\uff0c\u4e1a\u52a1\u6267\u884c\u65f6\u95f4\u957f\u7684\u95ee\u9898\uff0c\u4e5f\u53ef\u80fd\u9700\u8981\u5206\u6790\u4e00\u4e0b\uff0c\u770b\u770b\u80fd\u4e0d\u80fd\u4f7f\u7528\u4e2d\u95f4\u4ef6\u5bf9\u4efb\u52a1\u8fdb\u884c\u62c6\u5206\u548c\u89e3\u8026\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u8bf7\u95ee Java \u963b\u585e\u9501\u4e2d\u504f\u5411\u9501\u8f6c\u4e3a\u8f7b\u91cf\u7ea7\u9501\u7684\u5177\u4f53\u6761\u4ef6\u4e48\uff1f\u6211\u5728\u7f51\u4e0a\u641c\u7d22\u5230\u7684\u548c\u4e66\u4e0a\u770b\u5230\u7684\u5927\u591a\u662f\u4e00\u7b14\u7565\u8fc7\u4e86\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5347\u7ea7\u7684\u4ee3\u7801\u53ef\u4ee5\u5728 biasedLock.cpp\uff08openjdk1.8\uff09\u91cc\u7684\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\"><code>if (highest_lock != NULL) {<\/code><code>    \/\/ Fix up highest lock to contain displaced header and point<\/code><code>    \/\/ object at it<\/code><code>    highest_lock-&gt;set_displaced_header(unbiased_prototype);<\/code><code>    \/\/ Reset object header to point to displaced mark<\/code><code>    obj-&gt;set_mark(markOopDesc::encode(highest_lock));<\/code><code>    assert(!obj-&gt;mark()-&gt;has_bias_pattern(), \"illegal mark state: stack lock used bias bit\");<\/code><code>    if (TraceBiasedLocking &amp;&amp; (Verbose || !is_bulk)) {<\/code><code>      tty-&gt;print_cr(\"  Revoked bias of currently-locked object\");<\/code><code>    }<\/code><code>  }<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u9644\u4e0a\uff08\u6211\u7406\u89e3\u7684\uff09\u504f\u5411\u9501\u5347\u7ea7\u7684\u6d41\u7a0b\u56fe\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/gitee.com\/xmtblog\/img\/raw\/master\/WX20200327.png\" alt=\"\u504f\u5411\u9501\u5347\u7ea7\u6d41\u7a0b\u56fe\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u5728\u5b9e\u9645\u8fd0\u7528\u4e2d\u5982\u4f55\u6e05\u6670\u660e\u4e86\u5730\u89c2\u5bdf JVM \u7684\u8fd0\u7528\u8fc7\u7a0b\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u56fe\u5f62\u5de5\u5177 JProfiler\u3001JConsole\u3001Java VisualVM\uff0c\u547d\u4ee4jps\u3001jstack\u3001jmap\u3001jhat\u3001jstat\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u6570\u636e\u5e93\u66f4\u65b0\u65f6\u5019\u4f1a\u6709\u5931\u8d25\u60c5\u51b5\uff0c\u4e00\u822c\u4fee\u590d\u6570\u636e\u9700\u8981\u600e\u4e48\u64cd\u4f5c\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u8865\u507f\u548c\u91cd\u8bd5\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u95ee\uff1a\u4f7f\u7528 Spring data JPA \u65f6\uff0c\u662f\u76f4\u63a5\u5e8f\u5217\u5316 entity\uff0c\u8fd8\u662f\u518d\u5199\u4e00\u4e2a dto\uff0c\u5b58\u5165 ID \u52a0\u4e0a\u4e00\u4e9b\u5197\u4f59\u7684\u7528\u6237\u4fe1\u606f\u6765\u7684\u597d\uff0c\u5404\u6709\u4ec0\u4e48\u4f18\u7f3a\u70b9\uff1f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b54\uff1a\u4f01\u4e1a\u8bbe\u8ba1\u6a21\u5f0f\u4e2d\u6709\u4e00\u4e2a Active Record\uff0c\u5177\u4f53\u5185\u5bb9\u5fd8\u7684\u5dee\u4e0d\u591a\u4e86\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5176\u4ed6\u4e00\u4e9b\u4ea7\u54c1\u548c\u7ba1\u7406\u65b9\u9762\u7684\u975e\u6280\u672f\u95ee\u9898\u672c\u6587\u7565\u8fc7\uff01<\/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 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=4937\">\u4e00\u6b21\u963f\u91cc P8 \u7684\u95ee\u7b54\u4ea4\u8c08\u4e4b\u65c5\uff01<\/a><\/p><!-- <div class=\"bd-reward-stl\"><button id=\"bdRewardBtn\"><span><\/span><\/button><\/div> -->","protected":false},"excerpt":{"rendered":"<p>\u95ee\uff1a\u8bf7\u6559\u4e00\u4e2a\u95ee\u9898\uff0c\u5728\u5c40\u57df\u7f51\u5185\u5bf9\u4e00\u53f0\u7070\u5ea6\u673a\u5668\u8fdb\u884c\u538b\u6d4b\uff0c\u5982\u679c\u5e26\u5bbd\u88ab\u6253\u6ee1\u540e\uff0c\u538b\u6d4b\u7684\u6548\u679c\u4e5f\u5c31\u5230\u74f6\u9888\u4e86\uff0c\u90a3\u4e48\u95ee\u9898\u6765\u4e86\uff0c\u600e [&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":[1845,1846,1706,731,40],"class_list":["post-4937","post","type-post","status-publish","format-standard","hentry","category-java","tag-jconsole","tag-jmap","tag-jstat","tag-jvm","tag-visualvm"],"_links":{"self":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4937","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=4937"}],"version-history":[{"count":1,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4937\/revisions"}],"predecessor-version":[{"id":4938,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4937\/revisions\/4938"}],"wp:attachment":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4937"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4937"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4937"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}