{"id":547,"date":"2013-10-31T11:03:08","date_gmt":"2013-10-31T03:03:08","guid":{"rendered":"http:\/\/coderbee.net\/?p=547"},"modified":"2013-12-15T16:55:15","modified_gmt":"2013-12-15T08:55:15","slug":"jvm-%e5%9e%83%e5%9c%be%e5%9b%9e%e6%94%b6%e7%ae%97%e6%b3%95","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/jvm\/20131031\/547","title":{"rendered":"JVM \u5783\u573e\u56de\u6536\u7b97\u6cd5"},"content":{"rendered":"<p>\u300a\u6df1\u5165\u7406\u89e3Java\u865a\u62df\u673a\uff1aJVM\u9ad8\u7ea7\u7279\u6027\u4e0e\u6700\u4f73\u5b9e\u8df5\u300b-\u7b14\u8bb0<\/p>\n<h2>\u4e00\u3001\u6982\u8ff0<\/h2>\n<p>\u5783\u573e\u56de\u6536\uff0cGarbage Collection\uff0c\u7b80\u79f0GC\u3002<\/p>\n<p>GC\u9700\u8981\u5b8c\u6210\u4e09\u4ef6\u4e8b\uff1a<\/p>\n<ul>\n<li>\u54ea\u4e9b\u5185\u5b58\u9700\u8981\u56de\u6536\uff1f<\/li>\n<li>\u4ec0\u4e48\u65f6\u5019\u56de\u6536\uff1f<\/li>\n<li>\u5982\u4f55\u56de\u6536\uff1f<br 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Roots\u5f00\u59cb\u8fdb\u884c\u53ef\u8fbe\u6027\u5206\u6790\uff0c\u5224\u65ad\u54ea\u4e9b\u662f\u4e0d\u53ef\u8fbe\u5bf9\u8c61\u3002<\/p>\n<p>\u5bf9\u4e8e\u4e0d\u53ef\u8fbe\u5bf9\u8c61\uff0c\u5224\u65ad\u662f\u5426\u9700\u8981\u6267\u884c\u5176finalize\u65b9\u6cd5\uff0c\u5982\u679c\u5bf9\u8c61\u6ca1\u6709\u8986\u76d6finalize\u65b9\u6cd5\u6216\u5df2\u7ecf\u6267\u884c\u8fc7finalize\u65b9\u6cd5\u5219\u89c6\u4e3a\u4e0d\u9700\u8981\u6267\u884c\uff0c\u8fdb\u884c\u56de\u6536\uff1b\u5982\u679c\u9700\u8981\uff0c\u5219\u628a\u5bf9\u8c61\u52a0\u5165F-Queue\u961f\u5217\u3002<\/p>\n<p>\u5bf9\u4e8eF-Queue\u961f\u5217\u91cc\u7684\u5bf9\u8c61\uff0c\u7a0d\u540e\u865a\u62df\u673a\u4f1a\u81ea\u52a8\u5efa\u7acb\u4e00\u4e2a\u4f4e\u4f18\u5148\u7ea7\u7684\u7ebf\u7a0b\u53bb\u89e6\u53d1\u5176finalize\u65b9\u6cd5\uff0c\u4f46\u4e0d\u4f1a\u7b49\u5f85\u8fd9\u4e2a\u65b9\u6cd5\u8fd4\u56de\u3002<\/p>\n<p>\u5982\u679c\u5728finalize\u65b9\u6cd5\u7684\u6267\u884c\u8fc7\u7a0b\u4e2d\uff0c\u5bf9\u8c61\u91cd\u65b0\u88ab\u5f15\u7528\uff0c\u90a3\u4e48\u8fdb\u884c\u7b2c\u4e8c\u6b21\u6807\u8bb0\u65f6\u5c06\u88ab\u79fb\u51faF-Queue\uff0c\u5728finalize\u65b9\u6cd5\u6267\u884c\u5b8c\u6210\u540e\uff0c\u5bf9\u8c61\u4ecd\u7136\u6ca1\u6709\u88ab\u5f15\u7528\uff0c\u5219\u8fdb\u884c\u56de\u6536\u3002<\/p>\n<p>\u5bf9\u4e8e\u88ab\u79fb\u51faF-Queue\u7684\u5bf9\u8c61\uff0c\u5982\u679c\u5b83\u4e0b\u4e00\u6b21\u9762\u4e34\u56de\u6536\u65f6\uff0c\u5c06\u4e0d\u4f1a\u518d\u6267\u884c\u5176finalize\u65b9\u6cd5\u3002<\/p>\n<p><strong>finalize\u65b9\u6cd5\u53ea\u6267\u884c\u4e00\u6b21\u3002<\/strong><\/p>\n<h2>\u56db\u3001\u5783\u573e\u6536\u96c6\u7b97\u6cd5<\/h2>\n<h3>\u6807\u8bb0-\u6e05\u9664\u7b97\u6cd5<\/h3>\n<p>Mark-Sweep\uff1a\u5148\u6807\u8bb0\u6240\u6709\u9700\u8981\u56de\u6536\u5bf9\u8c61\uff0c\u7136\u540e\u7edf\u4e00\u56de\u6536\u3002<\/p>\n<h4>\u95ee\u9898<\/h4>\n<ol>\n<li>\u6548\u7387\u95ee\u9898\uff0c\u6807\u8bb0\u548c\u6e05\u9664\u4e24\u4e2a\u8fc7\u7a0b\u7684\u6548\u7387\u90fd\u4e0d\u9ad8\u3002<\/li>\n<li>\u7a7a\u95f4\u95ee\u9898\uff0c\u4f1a\u4ea7\u751f\u5927\u91cf\u4e0d\u8fde\u7eed\u7684\u5185\u5b58\u788e\u7247\u3002\u5206\u914d\u5927\u5bf9\u8c61\u65f6\u5bb9\u6613\u63d0\u524d\u89e6\u53d1GC\u3002<\/li>\n<\/ol>\n<h3>\u590d\u5236\u7b97\u6cd5<\/h3>\n<p>Copying\uff1a\u628a\u53ef\u7528\u5185\u5b58\u5206\u4e3a\u5927\u5c0f\u76f8\u7b49\u7684\u4e24\u5757\uff0c\u6bcf\u6b21\u53ea\u4f7f\u7528\u4e00\u5757\u3002\u5f53\u4e00\u5757\u7528\u5b8c\u65f6\uff0c\u5c06\u5b58\u6d3b\u5bf9\u8c61\u590d\u5236\u5230\u53e6\u4e00\u5757\uff0c\u518d\u4e00\u6b21\u6e05\u7406\u6389\u5df2\u4f7f\u7528\u7684\u5185\u5b58\u5757\u3002<\/p>\n<p>\u5b9e\u73b0\u7b80\u5355\uff0c\u5206\u914d\u5feb\uff0c\u53ea\u9700\u8981\u987a\u5e8f\u79fb\u52a8\u5806\u9876\u6307\u9488\u5c31\u53ef\u4ee5\u8fdb\u884c\u5206\u914d\uff0c\u5141\u8bb8\u9ad8\u6548\u3002\u4ee3\u4ef7\u662f\u5185\u5b58\u6d6a\u8d39\u5927\u3002<\/p>\n<p>IBM\u7684\u7814\u7a76\u8868\u660e\uff0c\u65b0\u4ea7\u751f\u7684\u5bf9\u8c6198%\u90fd\u662f\u5f88\u5feb\u5c31\u6b7b\u5fd9\u7684\u3002<\/p>\n<p>HotSpot\u5c06\u5185\u5b58\u5206\u4e3a\u4e00\u5757\u8f83\u5927\u7684Eden\u548c\u4e24\u5757\u8f83\u5c0f\u7684Survivor\u7a7a\u95f4\uff0c\u6bcf\u6b21\u4f7f\u7528Eden\u548c\u5176\u4e2d\u4e00\u5757Survivor\u3002\u56de\u6536\u65f6\uff0c\u5c06Eden\u548cSurvivor\u4e2d\u5b58\u6d3b\u7684\u5bf9\u8c61\u4e00\u6b21\u6027\u590d\u5236\u5230\u53e6\u4e00\u4e2aSurvivor\u4e0a\uff0c\u7136\u540e\u6e05\u7406\u6389Eden\u548c\u7528\u8fc7\u7684Survivor\u3002<\/p>\n<p>\u5728\u4e0a\u9762\u7684\u590d\u5236\u8fc7\u7a0b\u4e2d\uff0c\u5982\u679cSurvivor\u7a7a\u95f4\u4e0d\u591f\uff0c\u5219\u9700\u8981\u5f15\u5165\u4e00\u79cd\u5206\u914d\u62c5\u4fdd\u673a\u5236\u6765\u5904\u7406\uff0c\u5728HotSpot\u4e2d\u662f\u5c06\u5bf9\u8c61\u5206\u914d\u5230\u5e74\u8001\u4ee3\u3002<\/p>\n<h3>\u6807\u8bb0-\u538b\u7f29<\/h3>\n<p>Mark-Compact\uff1a\u5148\u6807\u8bb0\uff0c\u7136\u540e\u5c06\u5b58\u6d3b\u5bf9\u8c61\u79fb\u5411\u4e00\u8fb9\uff0c\u518d\u6e05\u7406\u6389\u8fb9\u754c\u4ee5\u5916\u7684\u5185\u5b58\u3002<\/p>\n<h3>\u5206\u4ee3\u6536\u96c6\u7b97\u6cd5<\/h3>\n<p>\u4e00\u822c\u7684\u865a\u62df\u673a\u90fd\u662f\u5206\u4ee3\u6536\u96c6\u7b97\u6cd5\uff0c\u4e5f\u5c31\u662f\u628a\u5185\u5b58\u5206\u4e3a\u51e0\u4e2a\u5757\uff0c\u4e0d\u540c\u7684\u5757\u7528\u4e0d\u540c\u7684\u56de\u6536\u7b97\u6cd5\u3002<\/p>\n<p>\u4e00\u822c\u5c06\u5185\u5b58\u5206\u4e3a\u65b0\u751f\u4ee3\u548c\u5e74\u8001\u4ee3\uff0c\u5728\u65b0\u751f\u4ee3\u4e00\u822c\u91c7\u7528\u590d\u5236\u7b97\u6cd5\uff0c\u5e74\u8001\u4ee3\u91c7\u7528\u6807\u8bb0-\u538b\u7f29\u7b97\u6cd5\u3002<\/p>\n<h3>\u4e94\u3001Java \u91cc\u7684\u5f15\u7528<\/h3>\n<ul>\n<li>\u5f3a\u5f15\u7528\uff08Strong Reference\uff09\uff1a\u4e00\u822c\u7684\u8d4b\u503c\u5c31\u662f\u5efa\u7acb\u5f3a\u5f15\u7528\uff0c\u53ea\u8981\u6709\u5f3a\u5f15\u7528\u5c31\u4e0d\u4f1a\u88ab\u56de\u6536\u3002<\/li>\n<li>\u8f6f\u5f15\u7528\uff08Soft  Reference\uff09\uff1a\u5728\u7cfb\u7edf\u5c06\u8981\u53d1\u751f\u5185\u5b58\u6ea2\u51fa\u65f6\u8fdb\u884c\u56de\u6536\uff0c\u5982\u679c\u56de\u6536\u540e\u8fd8\u662f\u4e0d\u591f\u5185\u5b58\u624d\u8dd1\u51fa\u5185\u5b58\u6ea2\u51fa\u5f02\u5e38\u3002\u5185\u5b58\u8db3\u591f\u5219\u4e0d\u4f1a\u56de\u6536\u3002<\/li>\n<li>\u5f31\u5f15\u7528\uff08Weak Reference\uff09\uff1a\u53ea\u80fd\u5b58\u6d3b\u5230\u4e0b\u4e00\u6b21GC\u65f6\uff0c\u4e0d\u7ba1\u5185\u5b58\u662f\u5426\u8db3\u591f\u3002<\/li>\n<li>\u865a\u5f15\u7528\uff08Phantom Reference\uff09\uff1a\u5bf9\u5bf9\u8c61\u7684\u751f\u5b58\u65f6\u95f4\u6ca1\u5f71\u54cd\uff0c\u76ee\u7684\u662f\u4e3a\u4e86\u5728\u5bf9\u8c61\u88ab\u56de\u6536\u65f6\u5f97\u5230\u7cfb\u7edf\u901a\u77e5\u3002<\/li>\n<\/ul>\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>\u300a\u6df1\u5165\u7406\u89e3Java\u865a\u62df\u673a\uff1aJVM\u9ad8\u7ea7\u7279\u6027\u4e0e\u6700\u4f73\u5b9e\u8df5\u300b-\u7b14\u8bb0 \u4e00\u3001\u6982\u8ff0 \u5783\u573e\u56de\u6536\uff0c &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/jvm\/20131031\/547\">\u7ee7\u7eed\u9605\u8bfb <span 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