{"id":646,"date":"2013-12-16T15:55:47","date_gmt":"2013-12-16T07:55:47","guid":{"rendered":"http:\/\/coderbee.net\/?p=646"},"modified":"2017-12-18T11:59:30","modified_gmt":"2017-12-18T03:59:30","slug":"gc-%e6%97%a5%e5%bf%97%e5%88%86%e6%9e%90","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/jvm\/20131216\/646","title":{"rendered":"GC \u65e5\u5fd7\u5206\u6790"},"content":{"rendered":"<p><strong>\u4e0d\u540c\u7684JVM\u53ca\u5176\u9009\u9879\u4f1a\u8f93\u51fa\u4e0d\u540c\u7684\u65e5\u5fd7\u3002<\/strong><\/p>\n<h2>GC \u65e5\u5fd7<\/h2>\n<p>\u751f\u6210\u4e0b\u9762\u65e5\u5fd7\u4f7f\u7528\u7684\u9009\u9879\uff1a<code>-XX:+PrintGCTimeStamps   -XX:+PrintGCDetails  -Xloggc:d:\/GClogs\/tomcat6-gc.log<\/code>\u3002<\/p>\n<pre>\r\n4.231: [GC 4.231: [DefNew: 4928K->512K(4928K), 0.0044047 secs] 6835K->3468K(15872K), 0.0045291 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]\r\n \r\n4.445: [Full GC (System) 4.445: [Tenured: 2956K->3043K(10944K), 0.1869806 secs] 4034K->3043K(15872K), [Perm : 3400K->3400K(12288K)], 0.1870847 secs] [Times: user=0.05 sys=0.00, real=0.19 secs] \r\n<\/pre>\n<p>\u6700\u524d\u9762\u7684\u6570\u5b57 <code>4.231<\/code> \u548c <code>4.445<\/code> \u4ee3\u8868\u865a\u62df\u673a\u542f\u52a8\u4ee5\u6765\u7684\u79d2\u6570\u3002<\/p>\n<p><code>[GC<\/code> \u548c <code>[Full GC<\/code> \u662f\u5783\u573e\u56de\u6536\u7684\u505c\u987f\u7c7b\u578b\uff0c\u800c\u4e0d\u662f\u533a\u5206\u662f\u65b0\u751f\u4ee3\u8fd8\u662f\u5e74\u8001\u4ee3\uff0c\u5982\u679c\u6709 <code>Full<\/code> \u8bf4\u660e\u53d1\u751f\u4e86 <code>Stop-The-World<\/code> \u3002\u5982\u679c\u662f\u8c03\u7528 <code>System.gc()<\/code> \u89e6\u53d1\u7684\uff0c\u90a3\u4e48\u5c06\u663e\u793a\u7684\u662f <code>[Full GC (System)<\/code> \u3002<\/p>\n<p>\u63a5\u4e0b\u6765\u7684 <code>[DefNew<\/code>,  <code>[Tenured<\/code>,  <code>[Perm<\/code> \u8868\u793a GC \u53d1\u751f\u7684\u533a\u57df\uff0c\u533a\u57df\u7684\u540d\u79f0\u4e0e\u4f7f\u7528\u7684 GC \u6536\u96c6\u5668\u76f8\u5173\u3002<br \/>\nSerial \u6536\u96c6\u5668\u4e2d\u65b0\u751f\u4ee3\u540d\u4e3a &#8220;Default New Generation&#8221;\uff0c\u663e\u793a\u7684\u540d\u5b57\u4e3a &#8220;[DefNew&#8221;\u3002\u5bf9\u4e8eParNew\u6536\u96c6\u5668\uff0c\u663e\u793a\u7684\u662f &#8220;[ParNew&#8221;\uff0c\u8868\u793a \u201cParallel New Generation\u201d\u3002 \u5bf9\u4e8e Parallel Scavenge \u6536\u96c6\u5668\uff0c\u65b0\u751f\u4ee3\u540d\u4e3a &#8220;PSYoungGen&#8221;\u3002\u5e74\u8001\u4ee3\u548c\u6c38\u4e45\u4ee3\u4e5f\u76f8\u540c\uff0c\u540d\u79f0\u90fd\u7531\u6536\u96c6\u5668\u51b3\u5b9a\u3002<\/p>\n<p>\u65b9\u62ec\u53f7\u5185\u90e8\u663e\u793a\u7684 \u201c4928K->512K(4928K)\u201d \u8868\u793a \u201cGC \u524d\u8be5\u533a\u57df\u5df2\u4f7f\u7528\u5bb9\u91cf  -> GC \u540e\u8be5\u533a\u57df\u5df2\u4f7f\u7528\u5bb9\u91cf (\u8be5\u533a\u57df\u5185\u5b58\u603b\u5bb9\u91cf) \u201d\u3002<\/p>\n<p>\u518d\u5f80\u540e\u7684 \u201c0.0044047 secs\u201d \u8868\u793a\u8be5\u533a\u57dfGC\u6240\u7528\u65f6\u95f4\uff0c\u5355\u4f4d\u662f\u79d2\u3002<\/p>\n<p>\u518d\u5f80\u540e\u7684 \u201c6835K->3468K(15872K)\u201d \u8868\u793a \u201cGC \u524dJava\u5806\u5df2\u4f7f\u7528\u5bb9\u91cf  ->  GC\u540eJava\u5806\u5df2\u4f7f\u7528\u5bb9\u91cf \uff08Java\u5806\u603b\u5bb9\u91cf\uff09\u201d\u3002<\/p>\n<p>\u518d\u5f80\u540e\u7684 \u201c0.0045291 secs\u201d \u662fJava\u5806GC\u6240\u7528\u7684\u603b\u65f6\u95f4\u3002<\/p>\n<p>\u6700\u540e\u7684 \u201c[Times: user=0.00 sys=0.00, real=0.00 secs]\u201d \u5206\u522b\u4ee3\u8868 \u7528\u6237\u6001\u6d88\u8017\u7684CPU\u65f6\u95f4\u3001\u5185\u6838\u6001\u6d88\u8017\u7684CPU\u65f6\u95f4 \u548c \u64cd\u4f5c\u4ece\u5f00\u59cb\u5230\u7ed3\u675f\u6240\u7ecf\u8fc7\u7684\u5899\u949f\u65f6\u95f4\u3002\u5899\u949f\u65f6\u95f4\u5305\u62ec\u5404\u79cd\u975e\u8fd0\u7b97\u7684\u7b49\u5f85\u8017\u65f6\uff0c\u5982IO\u7b49\u5f85\u3001\u7ebf\u7a0b\u963b\u585e\u3002CPU\u65f6\u95f4\u4e0d\u5305\u62ec\u7b49\u5f85\u65f6\u95f4\uff0c\u5f53\u7cfb\u7edf\u6709\u591a\u6838\u65f6\uff0c\u591a\u7ebf\u7a0b\u64cd\u4f5c\u4f1a\u53e0\u52a0\u8fd9\u4e9bCPU\u65f6\u95f4\uff0c\u6240\u4ee5user\u6216sys\u65f6\u95f4\u4f1a\u8d85\u8fc7real\u65f6\u95f4\u3002<\/p>\n<h2>\u5806\u7684\u5206\u4ee3<\/h2>\n<p><img decoding=\"async\" src=\"\/\/coderbee.net\/wp-content\/uploads\/2013\/12\/JVM-heap-generations.png\" alt=\"JVM-heap-generations\" \/><\/a><\/p>\n<p>\u5728\u4e0a\u56fe\u4e2d\uff1a<\/p>\n<ul>\n<li>young\u533a\u57df\u5c31\u662f\u65b0\u751f\u4ee3\uff0c\u5b58\u653e\u65b0\u521b\u5efa\u5bf9\u8c61\uff1b<\/li>\n<li>tenured\u662f\u5e74\u8001\u4ee3\uff0c\u5b58\u653e\u5728\u65b0\u751f\u4ee3\u7ecf\u5386\u591a\u6b21\u5783\u573e\u56de\u6536\u540e\u4ecd\u5b58\u6d3b\u7684\u5bf9\u8c61\uff1b<\/li>\n<li>perm\u662f\u6c38\u751f\u4ee3\uff0c\u5b58\u653e\u7c7b\u5b9a\u4e49\u4fe1\u606f\u3001\u5143\u6570\u636e\u7b49\u4fe1\u606f\u3002<\/li>\n<\/ul>\n<p>\u5f53GC\u53d1\u751f\u5728\u65b0\u751f\u4ee3\u65f6\uff0c\u79f0\u4e3aMinor GC\uff0c\u6b21\u6536\u96c6\uff1b\u5f53GC\u53d1\u751f\u5728\u5e74\u8001\u4ee3\u65f6\uff0c\u79f0\u4e3aMajor GC\uff0c\u4e3b\u6536\u96c6\u3002 \u4e00\u822c\u7684\uff0cMinor GC\u7684\u53d1\u751f\u9891\u7387\u8981\u6bd4Major GC\u9ad8\u5f88\u591a\u3002<\/p>\n<h2>JVM GC \u76f8\u5173\u7684\u9009\u9879<\/h2>\n<pre>\r\n-XX:+PrintGC \u8f93\u51faGC\u65e5\u5fd7\r\n-XX:+PrintGCDetails \u8f93\u51faGC\u7684\u8be6\u7ec6\u65e5\u5fd7\r\n-XX:+PrintGCTimeStamps \u8f93\u51faGC\u7684\u65f6\u95f4\u6233\uff08\u4ee5\u57fa\u51c6\u65f6\u95f4\u7684\u5f62\u5f0f\uff09\r\n-XX:+PrintGCDateStamps \u8f93\u51faGC\u7684\u65f6\u95f4\u6233\uff08\u4ee5\u65e5\u671f\u7684\u5f62\u5f0f\uff0c\u5982 2013-05-04T21:53:59.234+0800\uff09\r\n-XX:+PrintHeapAtGC \u5728\u8fdb\u884cGC\u7684\u524d\u540e\u6253\u5370\u51fa\u5806\u7684\u4fe1\u606f\r\n-Xloggc:..\/logs\/gc.log \u65e5\u5fd7\u6587\u4ef6\u7684\u8f93\u51fa\u8def\u5f84\r\n<\/pre>\n<hr\/>\n<p>\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u5fae\u4fe1\u516c\u4f17\u53f7: <strong>coderbee\u7b14\u8bb0<\/strong>\uff0c\u53ef\u4ee5\u66f4\u53ca\u65f6\u56de\u590d\u4f60\u7684\u8ba8\u8bba\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"258\" height=\"258\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/coderbee-note.jpg\" class=\"alignnone size-full wp-image-1707\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e0d\u540c\u7684JVM\u53ca\u5176\u9009\u9879\u4f1a\u8f93\u51fa\u4e0d\u540c\u7684\u65e5\u5fd7\u3002 GC \u65e5\u5fd7 \u751f\u6210\u4e0b\u9762\u65e5\u5fd7\u4f7f\u7528\u7684\u9009\u9879\uff1a-X &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/jvm\/20131216\/646\">\u7ee7\u7eed\u9605\u8bfb <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[96],"tags":[101,233,132],"_links":{"self":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/646"}],"collection":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/comments?post=646"}],"version-history":[{"count":4,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/646\/revisions"}],"predecessor-version":[{"id":1591,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/646\/revisions\/1591"}],"wp:attachment":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/media?parent=646"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/categories?post=646"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/tags?post=646"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}