{"id":306,"date":"2012-09-08T13:55:38","date_gmt":"2012-09-08T05:55:38","guid":{"rendered":"http:\/\/www.sulabs.net\/?p=306"},"modified":"2012-09-18T09:58:30","modified_gmt":"2012-09-18T01:58:30","slug":"jvm-%e5%8f%82%e6%95%b0%e8%ae%be%e7%bd%ae%e8%af%a6%e7%bb%86%e8%af%b4%e6%98%8e","status":"publish","type":"post","link":"https:\/\/www.sulabs.net\/?p=306","title":{"rendered":"JVM \u53c2\u6570\u8bbe\u7f6e\u8be6\u7ec6\u8bf4\u660e"},"content":{"rendered":"<p>\u8f6c\u81eahttp:\/\/17studio.javaeye.com\/blog\/443439<\/p>\n<p>JVM \u53c2\u6570\u8bbe\u7f6e\u8be6\u7ec6\u8bf4\u660e<\/p>\n<p>1: heap size<br \/>\na: -Xmx&lt;n&gt;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u6307\u5b9a jvm \u7684\u6700\u5927 heap \u5927\u5c0f , \u5982 :-Xmx=2g<\/p>\n<p>b: -Xms&lt;n&gt;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u6307\u5b9a jvm \u7684\u6700\u5c0f heap \u5927\u5c0f , \u5982 :-Xms=2g \uff0c \u9ad8\u5e76\u53d1\u5e94\u7528\uff0c \u5efa\u8bae\u548c-Xmx\u4e00\u6837\uff0c \u9632\u6b62\u56e0\u4e3a\u5185\u5b58\u6536\u7f29\uff0f\u7a81\u7136\u589e\u5927\u5e26\u6765\u7684\u6027\u80fd\u5f71\u54cd\u3002<\/p>\n<p>c: -Xmn&lt;n&gt;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u6307\u5b9a jvm \u4e2d New Generation \u7684\u5927\u5c0f , \u5982 :-Xmn256m\u3002 \u8fd9\u4e2a\u53c2\u6570\u5f88\u5f71\u54cd\u6027\u80fd\uff0c \u5982\u679c\u4f60\u7684\u7a0b\u5e8f\u9700\u8981\u6bd4\u8f83\u591a\u7684\u4e34\u65f6\u5185\u5b58\uff0c \u5efa\u8bae\u8bbe\u7f6e\u5230512M\uff0c \u5982\u679c\u7528\u7684\u5c11\uff0c \u5c3d\u91cf\u964d\u4f4e\u8fd9\u4e2a\u6570\u503c\uff0c \u4e00\u822c\u6765\u8bf4128\uff0f256\u8db3\u4ee5\u4f7f\u7528\u4e86\u3002<br \/>\n<!--more--><br \/>\nd: -XX:PermSize=&lt;n&gt;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u6307\u5b9a jvm \u4e2d Perm Generation \u7684\u6700\u5c0f\u503c , \u5982 :-XX:PermSize=32m\u3002 \u8fd9\u4e2a\u53c2\u6570\u9700\u8981\u770b\u4f60\u7684\u5b9e\u9645\u60c5\u51b5\uff0c\u3002 \u53ef\u4ee5\u901a\u8fc7jmap \u547d\u4ee4\u770b\u770b\u5230\u5e95\u9700\u8981\u591a\u5c11\u3002<\/p>\n<p>e: -XX:MaxPermSize=&lt;n&gt;\u00a0\u00a0 \u6307\u5b9a Perm Generation \u7684\u6700\u5927\u503c , \u5982 :-XX:MaxPermSize=64m<\/p>\n<p>f: -Xss&lt;n&gt;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u6307\u5b9a\u7ebf\u7a0b\u685f\u5927\u5c0f , \u5982 :-Xss128k\uff0c \u4e00\u822c\u6765\u8bf4\uff0cwebx\u6846\u67b6\u4e0b\u7684\u5e94\u7528\u9700\u8981256K\u3002 \u5982\u679c\u4f60\u7684\u7a0b\u5e8f\u6709\u5927\u89c4\u6a21\u7684\u9012\u5f52\u884c\u4e3a\uff0c \u8bf7\u8003\u8651\u8bbe\u7f6e\u5230512K\uff0f1M\u3002 \u8fd9\u4e2a\u9700\u8981\u5168\u9762\u7684\u6d4b\u8bd5\u624d\u80fd\u77e5\u9053\u3002 \u4e0d\u8fc7\uff0c 256K\u5df2\u7ecf\u5f88\u5927\u4e86\u3002 \u8fd9\u4e2a\u53c2\u6570\u5bf9\u6027\u80fd\u7684\u5f71\u54cd\u6bd4\u8f83\u5927\u7684\u3002<\/p>\n<p>g: -XX:NewRatio=&lt;n&gt;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u6307\u5b9a jvm \u4e2d Old Generation heap size \u4e0e New Generation \u7684\u6bd4\u4f8b , \u5728\u4f7f\u7528 CMS GC \u7684\u60c5\u51b5\u4e0b\u6b64\u53c2\u6570\u5931\u6548 , \u5982 :-XX:NewRatio=2<\/p>\n<p>h: -XX:SurvivorRatio=&lt;n&gt;\u00a0 \u00a0\u6307\u5b9a New Generation \u4e2d Eden Space \u4e0e\u4e00\u4e2a Survivor Space \u7684 heap size \u6bd4\u4f8b ,-XX:SurvivorRatio=8, \u90a3\u4e48\u5728\u603b\u5171 New Generation \u4e3a 10m \u7684\u60c5\u51b5\u4e0b ,Eden Space \u4e3a 8m<\/p>\n<p>i: -XX:MinHeapFreeRatio=&lt;n&gt; \u6307\u5b9a jvm heap \u5728\u4f7f\u7528\u7387\u5c0f\u4e8e n \u7684\u60c5\u51b5\u4e0b ,heap \u8fdb\u884c\u6536\u7f29 ,Xmx==Xms \u7684\u60c5\u51b5\u4e0b\u65e0\u6548 , \u5982 :-XX:MinHeapFreeRatio=30<\/p>\n<p>j: -XX:MaxHeapFreeRatio=&lt;n&gt; \u6307\u5b9a jvm heap \u5728\u4f7f\u7528\u7387\u5927\u4e8e n \u7684\u60c5\u51b5\u4e0b ,heap \u8fdb\u884c\u6269\u5f20 ,Xmx==Xms \u7684\u60c5\u51b5\u4e0b\u65e0\u6548 , \u5982 :-XX:MaxHeapFreeRatio=70<\/p>\n<p>k: -XX:LargePageSizeInBytes=&lt;n&gt; \u6307\u5b9a Java heap \u7684\u5206\u9875\u9875\u9762\u5927\u5c0f , \u5982 :-XX:LargePageSizeInBytes=128m<\/p>\n<p>2: garbage collector<br \/>\na: -XX:+UseParallelGC \u6307\u5b9a\u5728 New Generation \u4f7f\u7528 parallel collector, \u5e76\u884c\u6536\u96c6 , \u6682\u505c app threads, \u540c\u65f6\u542f\u52a8\u591a\u4e2a\u5783\u573e\u56de\u6536 thread, \u4e0d\u80fd\u548c CMS gc \u4e00\u8d77\u4f7f\u7528 . \u7cfb\u7edf\u5428\u5410\u91cf\u4f18\u5148 , \u4f46\u662f\u4f1a\u6709\u8f83\u957f\u957f\u65f6\u95f4\u7684 app pause, \u540e\u53f0\u7cfb\u7edf\u4efb\u52a1\u53ef\u4ee5\u4f7f\u7528\u6b64 gc<\/p>\n<p>b: -XX:ParallelGCThreads=&lt;n&gt; \u6307\u5b9a parallel collection \u65f6\u542f\u52a8\u7684 thread \u4e2a\u6570 , \u9ed8\u8ba4\u662f\u7269\u7406 processor \u7684\u4e2a\u6570 ,<\/p>\n<p>c: -XX:+UseParallelOldGC \u6307\u5b9a\u5728 Old Generation \u4f7f\u7528 parallel collector<\/p>\n<p>d: -XX:+UseParNewGC \u6307\u5b9a\u5728 New Generation \u4f7f\u7528 parallel collector, \u662f UseParallelGC \u7684 gc \u7684\u5347\u7ea7\u7248\u672c , \u6709\u66f4\u597d\u7684\u6027\u80fd\u6216\u8005\u4f18\u70b9 , \u53ef\u4ee5\u548c CMS gc \u4e00\u8d77\u4f7f\u7528<\/p>\n<p>e: -XX:+CMSParallelRemarkEnabled \u5728\u4f7f\u7528 UseParNewGC \u7684\u60c5\u51b5\u4e0b , \u5c3d\u91cf\u51cf\u5c11 mark \u7684\u65f6\u95f4<\/p>\n<p>f: -XX:+UseConcMarkSweepGC \u6307\u5b9a\u5728 Old Generation \u4f7f\u7528 concurrent cmark sweep gc,gc thread \u548c app thread \u5e76\u884c ( \u5728 init-mark \u548c remark \u65f6 pause app thread). app pause \u65f6\u95f4\u8f83\u77ed , \u9002\u5408\u4ea4\u4e92\u6027\u5f3a\u7684\u7cfb\u7edf , \u5982 web server<\/p>\n<p>g: -XX:+UseCMSCompactAtFullCollection \u5728\u4f7f\u7528 concurrent gc \u7684\u60c5\u51b5\u4e0b , \u9632\u6b62 memory fragmention, \u5bf9 live object \u8fdb\u884c\u6574\u7406 , \u4f7f memory \u788e\u7247\u51cf\u5c11<\/p>\n<p>h: -XX:CMSInitiatingOccupancyFraction=&lt;n&gt; \u6307\u793a\u5728 old generation \u5728\u4f7f\u7528\u4e86 n% \u7684\u6bd4\u4f8b\u540e , \u542f\u52a8 concurrent collector, \u9ed8\u8ba4\u503c\u662f 68, \u5982 :-XX:CMSInitiatingOccupancyFraction=70 \u6709\u4e2a bug, \u5728\u4f4e\u7248\u672c(1.5.09 and early)\u7684 jvm \u4e0a\u51fa\u73b0 , <a href=\"http:\/\/bugs.sun.com\/bugdatabase\/view_bug.do?bug_id=6486089\">http:\/\/bugs.sun.com\/bugdatabase\/view_bug.do?bug_id=6486089<\/a><\/p>\n<p>i: -XX:+UseCMSInitiatingOccupancyOnly \u6307\u793a\u53ea\u6709\u5728 old generation \u5728\u4f7f\u7528\u4e86\u521d\u59cb\u5316\u7684\u6bd4\u4f8b\u540e concurrent collector \u542f\u52a8\u6536\u96c6<\/p>\n<p>3:others<br \/>\na: -XX:MaxTenuringThreshold=&lt;n&gt; \u6307\u5b9a\u4e00\u4e2a object \u5728\u7ecf\u5386\u4e86 n \u6b21 young gc \u540e\u8f6c\u79fb\u5230 old generation \u533a , \u5728 linux64 \u7684 java6 \u4e0b\u9ed8\u8ba4\u503c\u662f 15, \u6b64\u53c2\u6570\u5bf9\u4e8e throughput collector \u65e0\u6548 , \u5982 :-XX:MaxTenuringThreshold=31<\/p>\n<p>b: -XX:+DisableExplicitGC \u7981\u6b62 java \u7a0b\u5e8f\u4e2d\u7684 full gc, \u5982 System.gc() \u7684\u8c03\u7528. \u6700\u597d\u52a0\u4e0a\u4e48\uff0c \u9632\u6b62\u7a0b\u5e8f\u5728\u4ee3\u7801\u91cc\u8bef\u7528\u4e86\u3002\u5bf9\u6027\u80fd\u9020\u6210\u51b2\u51fb\u3002<\/p>\n<p>c: -XX:+UseFastAccessorMethods get,set \u65b9\u6cd5\u8f6c\u6210\u672c\u5730\u4ee3\u7801<\/p>\n<p>d: -XX:+PrintGCDetails \u6253\u5e94\u5783\u573e\u6536\u96c6\u7684\u60c5\u51b5\u5982 : [GC 15610.466: [ParNew: 229689K-&gt;20221K(235968K), 0.0194460 secs] 1159829K-&gt;953935K(2070976K), 0.0196420 secs] \u00a0 e: -XX:+PrintGCTimeStamps \u6253\u5e94\u5783\u573e\u6536\u96c6\u7684\u65f6\u95f4\u60c5\u51b5 , \u5982 : [Times: user=0.09 sys=0.00, real=0.02 secs]<\/p>\n<p>f: -XX:+PrintGCApplicationStoppedTime \u6253\u5e94\u5783\u573e\u6536\u96c6\u65f6 , \u7cfb\u7edf\u7684\u505c\u987f\u65f6\u95f4 , \u5982 : Total time for which application threads were stopped: 0.0225920 seconds<\/p>\n<p>4: a web server product sample and process<br \/>\nJAVA_OPTS=\" -server -Xmx2g -Xms2g -Xmn256m -XX:PermSize=128m -Xss256k -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSParallelRemarkEnabled -XX:+UseCMSCompactAtFullCollection -XX:LargePageSizeInBytes=128m -XX:+UseFastAccessorMethods -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=70 \" \u00a0 \u6700\u521d\u7684\u65f6\u5019\u6211\u4eec\u7528 UseParallelGC \u548c UseParallelOldGC,heap \u5f00\u4e86 3G,NewRatio \u8bbe\u6210 1. \u8fd9\u6837\u7684\u914d\u7f6e\u4e0b young gc \u53d1\u751f\u9891\u7387\u7ea6 12,3 \u79d2\u4e00\u6b21 , \u5e73\u5747\u6bcf\u6b21\u82b1\u8d39 80ms \u5de6\u53f3 ,full gc \u53d1\u751f\u7684\u9891\u7387\u6781\u4f4e , \u6bcf\u6b21\u6d88\u8017 1s \u5de6\u53f3 . \u4ece\u6240\u6709 gc \u6d88\u8017\u7cfb\u7edf\u65f6\u95f4\u770b , \u7cfb\u7edf\u4f7f\u7528\u7387\u8fd8\u662f\u6ee1\u9ad8\u7684 , \u4f46\u662f\u4e0d\u8bba\u662f young gc \u8fd8\u662f old gc,applicaton thread pause \u7684\u65f6\u95f4\u6bd4\u8f83\u957f , \u4e0d\u5408\u9002 web \u5e94\u7528 . \u6211\u4eec\u4e5f\u8c03\u5c0f New Generation \u7684 , \u4f46\u662f\u8fd9\u6837\u4f1a\u4f7f full gc \u65f6\u95f4\u52a0\u957f . \u00a0 \u540e\u6765\u6211\u4eec\u5c31\u7528 CMS gc(-XX:+UseConcMarkSweepGC), \u5f53\u65f6\u7684\u603b heap \u8fd8\u662f 3g, \u65b0\u751f\u4ee3 1.5g \u540e , \u89c2\u5bdf\u4e0d\u662f\u5f88\u7406\u60f3 , \u6539\u4e3a jvm heap \u4e3a 2g \u65b0\u751f\u4ee3\u8bbe\u7f6e -Xmn1g, \u5728\u8fd9\u6837\u7684\u60c5\u51b5\u4e0b young gc \u53d1\u751f\u7684\u9891\u7387\u53d8\u6210 ,7,8 \u5999\u4e00\u6b21 , \u5e73\u5747\u6bcf\u6b21\u65f6\u95f4 40~50 \u6beb\u79d2\u5de6\u53f3 ,CMS gc \u5f88\u5c11\u53d1\u751f , \u6bcf\u6b21\u65f6\u95f4\u5728 init-mark \u548c remark(two steps stop all app thread) \u603b\u5171\u5e73\u5747\u82b1\u8d39 80~90ms \u5de6\u53f3 . \u00a0 \u5728\u8fd9\u91cc\u6211\u4eec\u66fe\u7ecf New Generation \u8c03\u5927\u5230 1400m, \u603b\u5171 2g \u7684 jvm heap, \u5e73\u5747\u6bcf\u6b21 ygc \u82b1\u8d39\u65f6\u95f4 60~70ms \u5de6\u53f3 ,CMS gc \u7684 init-mark \u548c remark \u4e4b\u548c\u5e73\u5747\u5728 50ms \u5de6\u53f3 , \u8fd9\u91cc\u6211\u4eec\u610f\u8bc6\u5230\u9519\u8bef\u7684\u65b9\u5411 , \u6216\u8005\u8bf4 CMS \u7684\u4f5c\u7528 , \u6240\u4ee5\u8fdb\u884c\u4e86\u4fee\u6539 \u00a0 \u6700\u540e\u6211\u4eec\u8c03\u5c0f New Generation \u4e3a 256m,young gc 2,3 \u79d2\u53d1\u751f\u4e00\u6b21 , \u5e73\u5747\u505c\u987f\u65f6\u95f4\u5728 25 \u6beb\u79d2\u5de6\u53f3 ,CMS gc \u7684 init-mark \u548c remark \u4e4b\u548c\u5e73\u5747\u5728 50ms \u5de6\u53f3 , \u8fd9\u6837\u4f7f\u7cfb\u7edf\u6bd4\u8f83\u5e73\u6ed1 , \u7ecf\u538b\u529b\u6d4b\u8bd5 , \u8fd9\u4e2a\u914d\u7f6e\u4e0b\u7cfb\u7edf\u6027\u80fd\u662f\u6bd4\u8f83\u9ad8\u7684 \u00a0 \u5728\u4f7f\u7528 CMS gc \u7684\u65f6\u5019\u4ed6\u6709\u4e24\u79cd\u89e6\u53d1 gc \u7684\u65b9\u5f0f :gc \u4f30\u7b97\u89e6\u53d1\u548c heap \u5360\u7528\u89e6\u53d1 . \u6211\u4eec\u7684 1.5.0.09 \u73af\u5883\u4e0b\u6709\u6b21 old \u533a heap \u5360\u7528\u518d 30% \u5de6\u53f3 , \u5979\u5c31\u9891\u7e41 gc, \u4e2a\u4eba\u611f\u89c9\u7cfb\u7edf\u4f30\u7b97\u89e6\u53d1\u8fd9\u79cd\u65b9\u5f0f\u4e0d\u9760\u8c31 , \u8fd8\u662f\u7528 heap \u4f7f\u7528\u6bd4\u7387\u89e6\u53d1\u6bd4\u8f83\u7a33\u59a5 . \u00a0 \u8fd9\u4e9b\u6570\u636e\u90fd\u6765\u81ea 64 \u4f4d\u6d4b\u8bd5\u673a , \u8fc7\u7a0b\u4e2d\u7684\u6570\u636e\u90fd\u662f\u6211\u5728 jboss log \u627e\u7684 , \u5f53\u65f6\u6ca1\u6709\u8bb0\u4e0b\u6765 , \u53ef\u80fd\u5b58\u5728\u4e00\u70b9\u70b9\u504f\u5dee , \u4f46\u4e0d\u4f1a\u5f88\u5927 , \u57fa\u672c\u8fc7\u7a0b\u5c31\u662f\u8fd9\u6837 .<\/p>\n<p>5: \u603b\u7ed3 web server \u4f5c\u4e3a\u4ea4\u4e92\u6027\u8981\u6c42\u8f83\u9ad8\u7684\u5e94\u7528 , \u6211\u4eec\u5e94\u8be5\u4f7f\u7528 Parallel+CMS,UseParNewGC \u8fd9\u4e2a\u5728 jdk6 -server \u4e0a\u662f\u9ed8\u8ba4\u7684 ,new generation gc, \u65b0\u751f\u4ee3\u4e0d\u80fd\u592a\u5927 , \u8fd9\u6837\u6bcf\u6b21 pause \u4f1a\u77ed\u4e00\u4e9b .CMS mark-sweep generation \u53ef\u4ee5\u5927\u4e00\u4e9b , \u53ef\u4ee5\u6839\u636e pause time \u5b9e\u9645\u60c5\u51b5\u63a7\u5236<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u8f6c\u81eahttp:\/\/17studio.javaeye.com\/blog\/44343 &hellip;<\/p>\n<p class=\"read-more\"><a href=\"https:\/\/www.sulabs.net\/?p=306\">\u7ee7\u7eed\u9605\u8bfb &raquo;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[68,67],"class_list":["post-306","post","type-post","status-publish","format-standard","hentry","category-lamp","tag-jvm","tag-tomcat"],"_links":{"self":[{"href":"https:\/\/www.sulabs.net\/index.php?rest_route=\/wp\/v2\/posts\/306","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sulabs.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sulabs.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sulabs.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sulabs.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=306"}],"version-history":[{"count":6,"href":"https:\/\/www.sulabs.net\/index.php?rest_route=\/wp\/v2\/posts\/306\/revisions"}],"predecessor-version":[{"id":321,"href":"https:\/\/www.sulabs.net\/index.php?rest_route=\/wp\/v2\/posts\/306\/revisions\/321"}],"wp:attachment":[{"href":"https:\/\/www.sulabs.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=306"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sulabs.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=306"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sulabs.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=306"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}