{"id":507,"date":"2008-07-10T00:00:00","date_gmt":"2008-07-09T16:00:00","guid":{"rendered":"http:\/\/www.strongd.net\/?p=507"},"modified":"2011-07-15T09:29:56","modified_gmt":"2011-07-15T01:29:56","slug":"%e7%bc%96%e5%86%99%e5%af%b9gc%e5%8f%8b%e5%a5%bd%ef%bc%8c%e5%8f%88%e4%b8%8d%e6%b3%84%e6%bc%8f%e7%9a%84%e4%bb%a3%e7%a0%81","status":"publish","type":"post","link":"https:\/\/www.strongd.net\/?p=507","title":{"rendered":"\u7f16\u5199\u5bf9GC\u53cb\u597d\uff0c\u53c8\u4e0d\u6cc4\u6f0f\u7684\u4ee3\u7801"},"content":{"rendered":"<p><DIV class=blog_content><br \/>\n<P>&nbsp;&nbsp;&nbsp;\u4f5c\u8005\uff1a<A href=\"http:\/\/blog.csdn.net\/calvinxiu\/\"><FONT color=#669966>\u6c5f\u5357\u767d\u8863<\/FONT><\/A>\uff0c\u6700\u65b0\u7248\u94fe\u63a5\uff1a<A href=\"http:\/\/blog.csdn.net\/calvinxiu\/archive\/2007\/05\/22\/1621051.aspx\"><FONT color=#669966>http:\/\/blog.csdn.net\/calvinxiu\/archive\/2007\/05\/22\/1621051.aspx<\/FONT><\/A>\uff0c\u7248\u6743\u6240\u6709\uff0c\u8f6c\u8f7d\u8bf7\u4fdd\u7559\u539f\u6587\u94fe\u63a5\u3002 <\/P><br \/>\n<P>&nbsp;&nbsp;&nbsp; \u770b\u5230JavaOne2007\u4e0a\u6709\u7bc7\u300aGarbage-Collection-Friendly Programming\u300b\u768468\u9875PPT\uff0c\u5fc3\u60f3\u90fd2007\u4e86\u8fd8\u8c08\u8fd9\u4e2a\u57fa\u672c\u95ee\u9898\uff0c\u4e00\u5b9a\u603b\u7ed3\u5f97\u5f88\u5168\u9762\u4e86\u624d\u597d\u610f\u601d\u7ad9\u51fa\u6765\u8bb2\u5427\u3002&nbsp;&nbsp;&nbsp;&nbsp;<\/P><br \/>\n<P>GC\u7684\u57fa\u7840\u6982\u5ff5\u89c1\u4e0a\u7bc7\uff1a<A href=\"http:\/\/blog.csdn.net\/calvinxiu\/archive\/2007\/05\/18\/1614473.aspx\" target=_blank><FONT color=#000000>JDK5.0\u5783\u573e\u6536\u96c6\u4f18\u5316\u4e4b&#8211;Don&#8217;t Pause<\/FONT><\/A>&nbsp;&nbsp;<\/P><br \/>\n<P><STRONG>1.\u4f7f\u7528\u66f4\u591a\u751f\u547d\u5468\u671f\u77ed\u7684\u3001\u5c0f\u7684\u3001\u4e0d\u6539\u53d8\u6307\u5411(immutable)\u7684\u5bf9\u8c61\uff0c\u7f16\u5199\u6e05\u6670\u7684\u4ee3\u7801\u3002<\/STRONG> <\/P><br \/>\n<P>&nbsp;&nbsp;&nbsp; \u51fa\u4e8e\u61d2\u60f0\u4e5f\u597d\uff0c\u6734\u7d20\u7684\u8282\u4fed\u610f\u8bc6\u4e5f\u597d\uff0c\u6211\u4eec\u90fd\u4e60\u60ef\u5bf9\u4e00\u4e2a\u53d8\u91cf\u91cd\u7528\u518d\u91cd\u7528\u3002\u4f46\u662f&#8230;. <\/P><br \/>\n<UL><br \/>\n<LI>Java\u7684\u5783\u573e\u6536\u96c6\u5668\u559c\u6b22\u77ed\u751f\u547d\u5468\u671f\u7684\u5bf9\u8c61\uff0c\u5bf9\u8c61\u5982\u679c\u5728\u65b0\u751f\u4ee3\u5185\uff0c\u5728\u5783\u573e\u6536\u96c6\u53d1\u751f\u524d\u5c31\u6b7b\u6389\u4e86\uff0c\u5783\u573e\u6536\u96c6\u5668\u5c31\u4ec0\u4e48\u90fd\u4e0d\u7528\u505a\u4e86\u3002<br \/>\n<LI>\u73b0\u4ee3JVM\u6784\u5efa\u4e00\u4e2a\u65b0\u5bf9\u8c61\u53ea\u9700\u898110\u4e2a\u672c\u5730CPU\u6307\u4ee4\uff0c\u5e76\u4e0d\u5f31\u4e8eC\/C++\u3002 (\u4f46\u5783\u573e\u6536\u96c6\u6ca1\u6709\u538b\u7f29\u7b97\u6cd5\u65f6\u4f1a\u7a0d\u6162\uff0c\u66f4\u9891\u7e41\u7684New\u5bf9\u8c61\u4e5f\u5bfc\u81f4\u66f4\u9891\u7e41\u7684GC)\u3002<br \/>\n<LI>\u5927\u5bf9\u8c61\u7684\u5206\u914d\u6548\u7387\u66f4\u4f4e\uff0c\u800c\u4e14\u5bf9\u975e\u538b\u7f29\u7b97\u6cd5\u7684\u5783\u573e\u6536\u96c6\u5668\uff0c\u66f4\u5bb9\u6613\u9020\u6210\u788e\u7247\u3002<br \/>\n<LI>\u5bf9\u8c61\u91cd\u7528\u589e\u52a0\u4e86\u4ee3\u7801\u7684\u590d\u6742\u5ea6\uff0c\u964d\u4f4e\u4e86\u53ef\u8bfb\u6027\u3002 <\/LI><\/UL><br \/>\n<P>&nbsp;&nbsp;&nbsp;\u6240\u4ee5\u6709\u6807\u9898\u7684\u547c\u5401\uff0c\u6bd4\u5982\u4e0d\u8981\u5bb3\u6015\u4e3a\u4e2d\u95f4\u7ed3\u679c\u5206\u914d\u5c0f\u5bf9\u8c61\u3002\u4f46\u7f16\u7a0b\u4e60\u60ef\u7684\u6539\u53d8\u4e5f\u4e0d\u662f\u4e00\u671d\u4e00\u5915\u7684\u4e8b\u60c5\u3002 <\/P><br \/>\n<P><STRONG><\/STRONG><\/P><br \/>\n<P><STRONG>2.\u5c06\u7528\u5b8c\u7684\u5bf9\u8c61\u8bbe\u4e3aNULL\u5176\u5b9e\u6ca1\u4ec0\u4e48\u4f5c\u7528\u3002<\/STRONG> <\/P><br \/>\n<P>&nbsp;&nbsp;&nbsp; \u8c8c\u4f3c\u5f88\u9177\u7684\u628a\u5bf9\u8c61\u4e3b\u52a8\u8bbe\u4e3aNull \u7684&#8221;\u597d\u4e60\u60ef&#8221;\u5176\u5b9e\u6ca1\u4ec0\u4e48\u7528\uff0cJIT Compiler\u4f1a\u81ea\u52a8\u5206\u6790local\u53d8\u91cf\u7684\u751f\u547d\u5468\u671f\u3002<BR>&nbsp;&nbsp;&nbsp; \u53ea\u6709\u4e00\u4e2a\u4f8b\u5916\u60c5\u51b5\uff0c\u5c31\u662fString[1024] foo \u8fd9\u79cd\u8d64\u88f8\u88f8\u7684\u6570\u7ec4\uff0c\u4f60\u9700\u8981\u4e3b\u52a8\u7684foo[100]=null\u91ca\u653e\u7b2c100\u53f7\u5143\u7d20\uff0c\u6240\u4ee5\u6700\u597d\u8fd8\u662f\u76f4\u63a5\u7528ArrayList\u8fd9\u4e9b\u6807\u51c6\u5e93\u7b97\u4e86\u3002 <\/P><br \/>\n<P>&nbsp;<\/P><br \/>\n<P><STRONG>3.\u907f\u514d\u663e\u5f0fGC&#8211;System.gc()\u3002<\/STRONG> <\/P><br \/>\n<P>&nbsp;&nbsp;&nbsp; \u5927\u5bb6\u90fd\u77e5\u9053System.gc()\u4e0d\u597d\uff0cfull-gc\u6d6a\u8d39\u5de8\u5927\uff0cgc\u7684\u65f6\u673a\u628a\u63e1\u4e0d\u4e00\u5b9a\u5bf9\u7b49\u7b49\uff0c\u751a\u81f3\u6709-XX:+DisableExplicitGC\u7684JVM\u53c2\u6570\u6765\u7981\u6b62\u5b83\u3002 <\/P><br \/>\n<P>&nbsp;&nbsp;&nbsp;&nbsp;\u54c8\u54c8\uff0c\u4f46\u6211\u8fd8\u4e0d\u4f1a\u7528System.gc()\u5462\uff0c\u4e0d\u6015\u4e0d\u6015\u3002\u771f\u7684\u4e0d\u6015\u5417\uff1f <\/P><br \/>\n<UL><br \/>\n<LI>\u5148\u7528<A href=\"http:\/\/findbugs.sourceforge.net\/\"><FONT color=#669966>FindBugs<\/FONT><\/A> \u67e5\u4e00\u4e0b\u6240\u7528\u5230\u7684\u5168\u90e8\u7b2c\u4e09\u65b9\u7c7b\u5e93\u5427&#8230;<br \/>\n<LI>\u81f3\u5c11RMI \u5c31\u4f1a\u8001\u5b9e\u4e0d\u5ba2\u6c14\u7684\u6267\u884cSystem.gc()\u6765\u5b9e\u73b0\u5206\u5e03\u5f0fGC\u7b97\u6cd5\u3002\u4f46\u6211\u4e5f\u4e0d\u4f1a\u7528RMI\u554a\u3002\u90a3EJB\u5462\uff0cEJB\u53ef\u662f\u5efa\u5728RMI\u4e0a\u7684&#8230;. <\/LI><\/UL><br \/>\n<P>&nbsp;&nbsp;&nbsp; \u5982\u679c\u65e0\u53ef\u907f\u514d\uff0c\u7528-Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000 (\u5355\u4f4d\u4e3a\u5fae\u5999) \u589e\u5927\u5927GC\u7684\u95f4\u9694(\u539f\u9ed8\u8ba4\u503c\u4e3a1\u5206\u949f)\uff0c-XX:+ExplicitGCInvokesConcurrent \u8ba9System.gc() \u4e5fCMS\u5e76\u53d1\u6267\u884c\u3002 <\/P><br \/>\n<P>&nbsp;<\/P><br \/>\n<P><STRONG>4.\u7ee7\u7eed\u5343\u592b\u6240\u6307\u7684finalize()<\/STRONG> <\/P><br \/>\n<P><STRONG><\/STRONG>&nbsp;&nbsp;&nbsp; \u5927\u5bb6\u4e5f\u90fd\u77e5\u9053finalize()\u4e0d\u597d\uff0c\u5206\u914d\u4ee3\u4ef7\u6602\u8d35\uff0c\u91ca\u653e\u4ee3\u4ef7\u66f4\u6602\u8d35(\u8981\u591a\u8d70\u4e00\u4e2a\u5faa\u73af\uff0c\u800c\u4e14\u4ed6\u4eec\u6b7b\u5f97\u6162\uff0c\u548c\u4ed6\u4eec\u76f8\u5173\u8054\u7684\u5bf9\u8c61\u4e5f\u8ddf\u7740\u6b7b\u5f97\u6162\u4e86)\uff0c\u53c8\u4e0d\u786e\u5b9a\u80fd\u5426\u88ab\u8c03\u7528(JVM\u5f00\u59cb\u5173\u95ed\u65f6\uff0c\u5c31\u4e0d\u4f1a\u518d\u8fdb\u884c\u5783\u573e\u6536\u96c6)\uff0c\u53c8\u4e0d\u786e\u5b9a\u4f55\u65f6\u88ab\u8c03\u7528(GC\u65f6\u95f4\u4e0d\u5b9a\uff0c\u5373\u4f7fsystem.gc()\u4e5f\u53ea\u662f\u63d0\u9192\u800c\u4e0d\u662f\u5f3a\u8febGC\uff0c\u53c8\u4e0d\u786e\u5b9a\u4ee5\u4ec0\u4e48\u6837\u7684\u987a\u5e8f\u8c03\u7528\uff0c\u6240\u4ee5finalize\u4e0d\u662fC++\u7684\u6790\u6784\u51fd\u6570\uff0c\u4e5f\u4e0d\u50cfC++\u7684\u6790\u6784\u51fd\u6570\u3002 <\/P><br \/>\n<P>&nbsp;&nbsp; \u6211\u4eec\u90fd\u77e5\u9053\u554a\uff0c\u6240\u4ee5\u6211\u4ece\u6765\u90fd\u6ca1\u4f7f\u7528\u3002\u90fd\u662f\u5728\u663e\u5f0f\u7684\u7ef4\u62a4\u90a3\u4e9b\u5916\u90e8\u8d44\u6e90\uff0c\u6bd4\u5982\u5728finally{}\u91cc\u91ca\u653e\u3002 <\/P><br \/>\n<P>&nbsp;<\/P><br \/>\n<P><STRONG>5.WeakReference\/SoftReference<\/STRONG> <\/P><br \/>\n<P>&nbsp;&nbsp; \u8fd9\u662f\u4e2a\u5e73\u65f6\u4e0d\u600e\u4e48\u4f1a\u642d\u7406\uff0c\u5076\u7136\u77e5\u9053\u4e86\u53c8\u89c9\u5f97\u6709\u7528\u7684Java\u7279\u5f81\u3002\u5927\u5bb6\u90fd\u77e5\u9053Java\u91cc\u6240\u6709\u5bf9\u8c61\u9664int\u7b49\u57fa\u672c\u7c7b\u578b\u5916\uff0c\u90fd\u662fPass by Reference\u7684\u6307\u9488\uff0c\u5b9e\u4f8b\u53ea\u8981\u88ab\u4e00\u4e2a\u5bf9\u8c61\u8fde\u7740\uff0c\u5c31\u4e0d\u4f1a\u88ab\u6536\u96c6\u3002<BR>&nbsp;&nbsp;&nbsp; \u800cWeakReference\u5c31\u662f\u771f\u6b63\u610f\u4e49\u4e0a\u7684C++\u6307\u9488\uff0c\u53ea\u662f\u5355\u7eaf\u7684\u6307\u5411\u4e00\u4e2a\u5bf9\u8c61\uff0c\u800c\u4e0d\u4f1a\u5f71\u54cd\u5bf9\u8c61\u7684\u5f15\u7528\u8ba1\u6570\u3002<BR>&nbsp;&nbsp;&nbsp; \u800cSoftReference\u66f4\u7279\u522b\uff0c\u5728\u5185\u5b58\u8db3\u591f\u65f6\uff0c\u5bf9\u8c61\u4f1a\u56e0\u4e3aSoftReference\u7684\u5b58\u5728\u800c\u4e0d\u88ab\u6536\u96c6\uff0c\u4f46\u5185\u5b58\u4e0d\u8db3\u65f6\uff0c\u5bf9\u8c61\u5c31\u8fd8\u662f\u4f1a\u88ab\u6536\u96c6\uff0c\u600e\u4e48\u770b\u90fd\u662f\u505a\u7b80\u5355\u7f13\u5b58\u7684\u6599\u5b50\u3002\u4ee3\u7801\u5982\u4e0b\uff1a <BR><BR><\/P><br \/>\n<DIV style=\"BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; BACKGROUND: #e6e6e6; PADDING-BOTTOM: 4px; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 95%; WORD-BREAK: break-all; PADDING-TOP: 4px; BORDER-BOTTOM: windowtext 0.5pt solid\"><br \/>\n<DIV><IMG alt=\"\" src=\"http:\/\/images.csdn.net\/syntaxhighlighting\/OutliningIndicators\/None.gif\" align=top _counted=\"undefined\"><SPAN style=\"COLOR: #000000\">&nbsp;&nbsp;Foo&nbsp;foo&nbsp;<\/SPAN><SPAN style=\"COLOR: #000000\">=<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;<\/SPAN><SPAN style=\"COLOR: #0000ff\">new<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;Foo();&nbsp;<BR><IMG alt=\"\" src=\"http:\/\/images.csdn.net\/syntaxhighlighting\/OutliningIndicators\/None.gif\" align=top _counted=\"undefined\">&nbsp;&nbsp;SoftReference&nbsp;sr<\/SPAN><SPAN style=\"COLOR: #000000\">=<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;<\/SPAN><SPAN style=\"COLOR: #0000ff\">new<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;SoftReference(foo);&nbsp;<BR><IMG alt=\"\" src=\"http:\/\/images.csdn.net\/syntaxhighlighting\/OutliningIndicators\/None.gif\" align=top _counted=\"undefined\">&nbsp;&nbsp;Foo&nbsp;bar&nbsp;<\/SPAN><SPAN style=\"COLOR: #000000\">=<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;&nbsp;sr.get();&nbsp;<\/SPAN><\/DIV><\/DIV><br \/>\n<P>&nbsp; \u5982\u679cfoo\u5df2\u88ab\u5783\u573e\u6536\u96c6\uff0csr.get()\u4f1a\u8fd4\u56deNull; <\/P><br \/>\n<P>&nbsp; \u53e6\u5916\u8fd8\u6709\u4e00\u4e2aReferenceQueue\u7684\u673a\u5236\uff0c\u4f7f\u5f97\u5bf9\u8c61\u88ab\u56de\u6536\u65f6\u80fd\u83b7\u5f97\u901a\u77e5\uff0c\u6bd4finalize()\u5b8c\u5168\u4e0d\u77e5\u9053GC\u4f55\u65f6\u4f1a\u6267\u884c\u8981\u806a\u660e\u7684\u591a\u3002 <BR><BR><\/P><br \/>\n<DIV style=\"BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; BACKGROUND: #e6e6e6; PADDING-BOTTOM: 4px; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 95%; WORD-BREAK: break-all; PADDING-TOP: 4px; BORDER-BOTTOM: windowtext 0.5pt solid\"><br \/>\n<DIV><IMG alt=\"\" src=\"http:\/\/images.csdn.net\/syntaxhighlighting\/OutliningIndicators\/None.gif\" align=top _counted=\"undefined\"><SPAN style=\"COLOR: #000000\">&nbsp;&nbsp;ReferenceQueue&nbsp;rq&nbsp;<\/SPAN><SPAN style=\"COLOR: #000000\">=<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;<\/SPAN><SPAN style=\"COLOR: #0000ff\">new<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;ReferenceQueue();<BR><IMG alt=\"\" src=\"http:\/\/images.csdn.net\/syntaxhighlighting\/OutliningIndicators\/None.gif\" align=top _counted=\"undefined\">&nbsp;&nbsp;ref&nbsp;<\/SPAN><SPAN style=\"COLOR: #000000\">=<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;<\/SPAN><SPAN style=\"COLOR: #0000ff\">new<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;WeakReference(foo,&nbsp;rq);&nbsp;<BR><IMG alt=\"\" src=\"http:\/\/images.csdn.net\/syntaxhighlighting\/OutliningIndicators\/None.gif\" align=top _counted=\"undefined\">&nbsp;&nbsp;WeakReference&nbsp;cleaned&nbsp;<\/SPAN><SPAN style=\"COLOR: #000000\">=<\/SPAN><SPAN style=\"COLOR: #000000\">&nbsp;rq.pool();&nbsp;<BR><IMG alt=\"\" src=\"http:\/\/images.csdn.net\/syntaxhighlighting\/OutliningIndicators\/None.gif\" align=top _counted=\"undefined\"><\/SPAN><\/DIV><\/DIV><br \/>\n<P>&nbsp; cleaned\u5c31\u662f\u521a\u521a\u88abGC\u6389\u7684WeakReference\u3002<BR><\/P><br \/>\n<P><STRONG>6.\u5185\u5b58\u6cc4\u6f0f<\/STRONG> <\/P><br \/>\n<P><STRONG><\/STRONG>&nbsp;&nbsp; java \u4e0d\u662f\u6709\u5783\u573e\u6536\u96c6\u5668\u4e86\u5417\uff1f\u600e\u4e48\u8fd8\u6cc4\u6f0f\u554a\uff0c\u552c\u6211\u554a\uff1f\uff1f<BR>&nbsp;&nbsp; \u55ef\uff0c\u6b64\u6cc4\u6f0f\u975e\u6bd4\u6cc4\u6f0f\u3002C\/C++\u7684\u6cc4\u6f0f\uff0c\u662f\u5bf9\u8c61\u5df2\u4e0d\u53ef\u5230\u8fbe\uff0c\u800c\u5185\u5b58\u53c8\u6ca1\u6709\u56de\u6536\uff0c\u771f\u6b63\u7684\u5185\u5b58\u9ed1\u6d1e\u3002<BR>&nbsp;&nbsp; \u800cJava\u7684\u6cc4\u6f0f\uff0c\u5219\u662f\u56e0\u4e3a\u5404\u79cd\u539f\u56e0\uff0c\u5bf9\u8c61\u5bf9\u5e94\u7528\u5df2\u7ecf\u65e0\u7528\uff0c\u4f46\u4e00\u76f4\u88ab\u6301\u6709\uff0c\u4e00\u76f4\u53ef\u5230\u8fbe\u3002<BR>&nbsp;&nbsp; \u603b\u7ed3\u539f\u56e0\u65e0\u5916\u4e4e\u51e0\u65b9\u9762\uff1a <\/P><br \/>\n<OL><br \/>\n<LI>\u88ab\u751f\u547d\u5468\u671f\u6781\u957f\u7684\u96c6\u5408\u7c7b\u4e0d\u5f53\u6301\u6709\uff0c\u53f7\u79f0\u662fJava\u5185\u5b58\u6cc4\u6f0f\u7684\u9996\u56e0\u3002<BR>\u8fd9\u4e9b\u96c6\u5408\u7c7b\u7684\u751f\u547d\u5468\u671f\u901a\u5e38\u6781\u957f\uff0c\u800c\u4e14\u662f\u4e00\u4e2a\u8f85\u52a9\u7ba1\u7406\u6027\u8d28\u7684\u5bf9\u8c61\uff0c\u5728\u4e00\u4e2a\u4e1a\u52a1\u4e8b\u52a1\u8fd0\u884c\u5b8c\u540e\uff0c\u5982\u679c\u6ca1\u6709\u5c06\u67d0\u4e2a\u4e1a\u52a1\u5bf9\u8c61\u4e3b\u52a8\u7684\u4ece\u4e2d\u6e05\u9664\u7684\u8bdd\uff0c\u8fd9\u4e2a\u96c6\u5408\u5c31\u4f1a\u5403\u8d8a\u6765\u8d8a\u591a\u5185\u5b58\uff0c\u53ef\u4ee5\u7528WeakReference\uff0c\u5982WeakHashMap\uff0c\u4f7f\u5f97\u5b83\u6301\u6709\u7684\u5bf9\u8c61\u4e0d\u589e\u52a0\u5bf9\u8c61\u7684\u5f15\u7528\u6570\u3002<br \/>\n<LI>Scope\u5b9a\u4e49\u4e0d\u5bf9\uff0c\u8fd9\u4e2a\u5f88\u7b80\u5355\u4e86\uff0c\u65b9\u6cd5\u7684\u5c40\u90e8\u53d8\u91cf\u5b9a\u4e49\u6210\u7c7b\u7684\u53d8\u91cf\uff0c\u7c7b\u7684\u9759\u6001\u53d8\u91cf\u7b49\u3002<br \/>\n<LI>\u5f02\u5e38\u65f6\u6ca1\u6709\u52a0finally{}\u6765\u91ca\u653e\u67d0\u4e9b\u8d44\u6e90\uff0cJDBC\u65f6\u4ee3\u4e5f\u662f\u5f88\u666e\u904d\u7684\u4e8b\u60c5\u3002<br \/>\n<LI>\u53e6\u5916\u4e00\u4e9b\u6211\u4e86\u89e3\u4e0d\u6df1\u7684\u539f\u56e0\uff0c\u5982\uff1aSwing\u91cc\u7684Listener\u6ca1\u6709\u663e\u5f0fremove\uff1b\u5185\u90e8\u7c7b\u6301\u6709\u5916\u90e8\u5bf9\u8c61\u7684\u9690\u5f0f\u5f15\u7528\uff1bFinalizers\u9020\u6210\u5173\u8054\u5bf9\u8c61\u6ca1\u6709\u88ab\u53ca\u65f6\u6e05\u7a7a\u7b49\u3002 <\/LI><\/OL><br \/>\n<P><STRONG>\u5185\u5b58\u6cc4\u6f0f\u7684\u68c0\u6d4b<\/STRONG> <\/P><br \/>\n<P>\u6709\u4e0d\u5c11\u5de5\u5177\u8f85\u52a9\u505a\u8fd9\u4e2a\u4e8b\u60c5\u7684\uff0c\u5982\u679c\u624b\u4e0a\u4e00\u4e2a\u5de5\u5177\u4e5f\u6ca1\u6709\uff0c\u53ef\u4ee5\u7528JDK\u81ea\u5e26\u7684\u5c0f\u5de5\u5177\uff1a <\/P><br \/>\n<UL><br \/>\n<LI>\u770b\u770b\u8c01\u5360\u6ee1\u4e86Heap\uff1f<BR>\u7528JDK6\u7684jmap\u53ef\u4ee5\u663e\u793a\u8fd0\u884c\u7a0b\u5e8f\u4e2d\u5bf9\u8c61\u7684\u7c7b\u578b\uff0c\u4e2a\u6570\u4e0e\u6240\u5360\u7684\u5927\u5c0f<BR>\u5148\u7528jps \u627e\u5230\u8fdb\u7a0b\u53f7\uff0c\u7136\u540ejmap -histo pid \u663e\u793a\u6216 jmap -dump:file=heap_file_name pid \u5bfc\u51faheap\u6587\u4ef6<br \/>\n<LI>\u4e3a\u4ec0\u4e48\u8fd9\u4e9b\u5bf9\u8c61\u4ecd\u7136\u53ef\u4ee5\u5230\u8fbe\uff1f<BR>\u7528jhat(Java Heap Analysis Tool) \u5206\u6790\u521a\u624d\u5bfc\u51fa\u7684heap\u6587\u4ef6\u3002<BR>\u5148jhat heap_file_name\uff0c\u7136\u540e\u6253\u5f00\u6d4f\u89c8\u5668<A href=\"http:\/\/localhost:7000\/\"><FONT color=#669966>http:\/\/localhost:7000\/<\/FONT><\/A> \u6d4f\u89c8\u3002 <\/LI><\/UL><\/DIV><br \/>\n<DIV><\/DIV><\/p>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp;&nbsp;&nbsp;\u4f5c\u8005\uff1a\u6c5f\u5357\u767d\u8863\uff0c\u6700\u65b0\u7248\u94fe\u63a5\uff1ahttp:\/\/blog.csdn.net\/calvinxiu\/archive\/2007\/05\/22\/1621051.aspx\uff0c\u7248\u6743\u6240\u6709\uff0c\u8f6c\u8f7d\u8bf7\u4fdd\u7559\u539f\u6587\u94fe\u63a5\u3002 &nbsp;&nbsp;&nbsp; \u770b\u5230JavaOne2007\u4e0a\u6709\u7bc7\u300aGarbage-Collection-Friendly Programming\u300b\u768468\u9875PPT\uff0c\u5fc3\u60f3\u90fd2007\u4e86\u8fd8\u8c08\u8fd9\u4e2a\u57fa\u672c\u95ee\u9898\uff0c\u4e00\u5b9a\u603b\u7ed3\u5f97\u5f88\u5168\u9762\u4e86\u624d\u597d\u610f\u601d\u7ad9\u51fa\u6765\u8bb2\u5427\u3002&nbsp;&nbsp;&nbsp;&nbsp; GC\u7684\u57fa\u7840\u6982\u5ff5\u89c1\u4e0a\u7bc7\uff1aJDK5.0\u5783\u573e\u6536\u96c6\u4f18\u5316\u4e4b&#8211;Don&#8217;t Pause&nbsp;&nbsp; 1.\u4f7f\u7528\u66f4\u591a\u751f\u547d\u5468\u671f\u77ed\u7684\u3001\u5c0f\u7684\u3001\u4e0d\u6539\u53d8\u6307\u5411(immutable)\u7684\u5bf9\u8c61\uff0c\u7f16\u5199\u6e05\u6670\u7684\u4ee3\u7801\u3002 &nbsp;&nbsp;&nbsp; \u51fa\u4e8e\u61d2\u60f0\u4e5f\u597d\uff0c\u6734\u7d20\u7684\u8282\u4fed\u610f\u8bc6\u4e5f\u597d\uff0c\u6211\u4eec\u90fd\u4e60\u60ef\u5bf9\u4e00\u4e2a\u53d8\u91cf\u91cd\u7528\u518d\u91cd\u7528\u3002\u4f46\u662f&#8230;. Java\u7684\u5783\u573e\u6536\u96c6\u5668\u559c\u6b22\u77ed\u751f\u547d\u5468\u671f\u7684\u5bf9\u8c61\uff0c\u5bf9\u8c61\u5982\u679c\u5728\u65b0\u751f\u4ee3\u5185\uff0c\u5728\u5783\u573e\u6536\u96c6\u53d1\u751f\u524d\u5c31\u6b7b\u6389\u4e86\uff0c\u5783\u573e\u6536\u96c6\u5668\u5c31\u4ec0\u4e48\u90fd\u4e0d\u7528\u505a\u4e86\u3002 \u73b0\u4ee3JVM\u6784\u5efa\u4e00\u4e2a\u65b0\u5bf9\u8c61\u53ea\u9700\u898110\u4e2a\u672c\u5730CPU\u6307\u4ee4\uff0c\u5e76\u4e0d\u5f31\u4e8eC\/C++\u3002 (\u4f46\u5783\u573e\u6536\u96c6\u6ca1\u6709\u538b\u7f29\u7b97\u6cd5\u65f6\u4f1a\u7a0d\u6162\uff0c\u66f4\u9891\u7e41\u7684New\u5bf9\u8c61\u4e5f\u5bfc\u81f4\u66f4\u9891\u7e41\u7684GC)\u3002 \u5927\u5bf9\u8c61\u7684\u5206\u914d\u6548\u7387\u66f4\u4f4e\uff0c\u800c\u4e14\u5bf9\u975e\u538b\u7f29\u7b97\u6cd5\u7684\u5783\u573e\u6536\u96c6\u5668\uff0c\u66f4\u5bb9\u6613\u9020\u6210\u788e\u7247\u3002 \u5bf9\u8c61\u91cd\u7528\u589e\u52a0\u4e86\u4ee3\u7801\u7684\u590d\u6742\u5ea6\uff0c\u964d\u4f4e\u4e86\u53ef\u8bfb\u6027\u3002 &nbsp;&nbsp;&nbsp;\u6240\u4ee5\u6709\u6807\u9898\u7684\u547c\u5401\uff0c\u6bd4\u5982\u4e0d\u8981\u5bb3\u6015\u4e3a\u4e2d\u95f4\u7ed3\u679c\u5206\u914d\u5c0f\u5bf9\u8c61\u3002\u4f46\u7f16\u7a0b\u4e60\u60ef\u7684\u6539\u53d8\u4e5f\u4e0d\u662f\u4e00\u671d\u4e00\u5915\u7684\u4e8b\u60c5\u3002 2.\u5c06\u7528\u5b8c\u7684\u5bf9\u8c61\u8bbe\u4e3aNULL\u5176\u5b9e\u6ca1\u4ec0\u4e48\u4f5c\u7528\u3002 &nbsp;&nbsp;&nbsp; \u8c8c\u4f3c\u5f88\u9177\u7684\u628a\u5bf9\u8c61\u4e3b\u52a8\u8bbe\u4e3aNull \u7684&#8221;\u597d\u4e60\u60ef&#8221;\u5176\u5b9e\u6ca1\u4ec0\u4e48\u7528\uff0cJIT Compiler\u4f1a\u81ea\u52a8\u5206\u6790local\u53d8\u91cf\u7684\u751f\u547d\u5468\u671f\u3002&nbsp;&nbsp;&nbsp; \u53ea\u6709\u4e00\u4e2a\u4f8b\u5916\u60c5\u51b5\uff0c\u5c31\u662fString[1024] foo \u8fd9\u79cd\u8d64\u88f8\u88f8\u7684\u6570\u7ec4\uff0c\u4f60\u9700\u8981\u4e3b\u52a8\u7684foo[100]=null\u91ca\u653e\u7b2c100\u53f7\u5143\u7d20\uff0c\u6240\u4ee5\u6700\u597d\u8fd8\u662f\u76f4\u63a5\u7528ArrayList\u8fd9\u4e9b\u6807\u51c6\u5e93\u7b97\u4e86\u3002 &nbsp; 3.\u907f\u514d\u663e\u5f0fGC&#8211;System.gc()\u3002 &nbsp;&nbsp;&nbsp; \u5927\u5bb6\u90fd\u77e5\u9053System.gc()\u4e0d\u597d\uff0cfull-gc\u6d6a\u8d39\u5de8\u5927\uff0cgc\u7684\u65f6\u673a\u628a\u63e1\u4e0d\u4e00\u5b9a\u5bf9\u7b49\u7b49\uff0c\u751a\u81f3\u6709-XX:+DisableExplicitGC\u7684JVM\u53c2\u6570\u6765\u7981\u6b62\u5b83\u3002 &nbsp;&nbsp;&nbsp;&nbsp;\u54c8\u54c8\uff0c\u4f46\u6211\u8fd8\u4e0d\u4f1a\u7528System.gc()\u5462\uff0c\u4e0d\u6015\u4e0d\u6015\u3002\u771f\u7684\u4e0d\u6015\u5417\uff1f \u5148\u7528FindBugs \u67e5\u4e00\u4e0b\u6240\u7528\u5230\u7684\u5168\u90e8\u7b2c\u4e09\u65b9\u7c7b\u5e93\u5427&#8230; \u81f3\u5c11RMI \u5c31\u4f1a\u8001\u5b9e\u4e0d\u5ba2\u6c14\u7684\u6267\u884cSystem.gc()\u6765\u5b9e\u73b0\u5206\u5e03\u5f0fGC\u7b97\u6cd5\u3002\u4f46\u6211\u4e5f\u4e0d\u4f1a\u7528RMI\u554a\u3002\u90a3EJB\u5462\uff0cEJB\u53ef\u662f\u5efa\u5728RMI\u4e0a\u7684&#8230;. &nbsp;&nbsp;&nbsp; \u5982\u679c\u65e0\u53ef\u907f\u514d\uff0c\u7528-Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000 (\u5355\u4f4d\u4e3a\u5fae\u5999) \u589e\u5927\u5927GC\u7684\u95f4\u9694(\u539f\u9ed8\u8ba4\u503c\u4e3a1\u5206\u949f)\uff0c-XX:+ExplicitGCInvokesConcurrent \u8ba9System.gc() \u4e5fCMS\u5e76\u53d1\u6267\u884c\u3002 &nbsp; 4.\u7ee7\u7eed\u5343\u592b\u6240\u6307\u7684finalize() &nbsp;&nbsp;&nbsp; \u5927\u5bb6\u4e5f\u90fd\u77e5\u9053finalize()\u4e0d\u597d\uff0c\u5206\u914d\u4ee3\u4ef7\u6602\u8d35\uff0c\u91ca\u653e\u4ee3\u4ef7\u66f4\u6602\u8d35(\u8981\u591a\u8d70\u4e00\u4e2a\u5faa\u73af\uff0c\u800c\u4e14\u4ed6\u4eec\u6b7b\u5f97\u6162\uff0c\u548c\u4ed6\u4eec\u76f8\u5173\u8054\u7684\u5bf9\u8c61\u4e5f\u8ddf\u7740\u6b7b\u5f97\u6162\u4e86)\uff0c\u53c8\u4e0d\u786e\u5b9a\u80fd\u5426\u88ab\u8c03\u7528(JVM\u5f00\u59cb\u5173\u95ed\u65f6\uff0c\u5c31\u4e0d\u4f1a\u518d\u8fdb\u884c\u5783\u573e\u6536\u96c6)\uff0c\u53c8\u4e0d\u786e\u5b9a\u4f55\u65f6\u88ab\u8c03\u7528(GC\u65f6\u95f4\u4e0d\u5b9a\uff0c\u5373\u4f7fsystem.gc()\u4e5f\u53ea\u662f\u63d0\u9192\u800c\u4e0d\u662f\u5f3a\u8febGC\uff0c\u53c8\u4e0d\u786e\u5b9a\u4ee5\u4ec0\u4e48\u6837\u7684\u987a\u5e8f\u8c03\u7528\uff0c\u6240\u4ee5finalize\u4e0d\u662fC++\u7684\u6790\u6784\u51fd\u6570\uff0c\u4e5f\u4e0d\u50cfC++\u7684\u6790\u6784\u51fd\u6570\u3002 &nbsp;&nbsp; \u6211\u4eec\u90fd\u77e5\u9053\u554a\uff0c\u6240\u4ee5\u6211\u4ece\u6765\u90fd\u6ca1\u4f7f\u7528\u3002\u90fd\u662f\u5728\u663e\u5f0f\u7684\u7ef4\u62a4\u90a3\u4e9b\u5916\u90e8\u8d44\u6e90\uff0c\u6bd4\u5982\u5728finally{}\u91cc\u91ca\u653e\u3002 &nbsp; 5.WeakReference\/SoftReference &nbsp;&nbsp; \u8fd9\u662f\u4e2a\u5e73\u65f6\u4e0d\u600e\u4e48\u4f1a\u642d\u7406\uff0c\u5076\u7136\u77e5\u9053\u4e86\u53c8\u89c9\u5f97\u6709\u7528\u7684Java\u7279\u5f81\u3002\u5927\u5bb6\u90fd\u77e5\u9053Java\u91cc\u6240\u6709\u5bf9\u8c61\u9664int\u7b49\u57fa\u672c\u7c7b\u578b\u5916\uff0c\u90fd\u662fPass by Reference\u7684\u6307\u9488\uff0c\u5b9e\u4f8b\u53ea\u8981\u88ab\u4e00\u4e2a\u5bf9\u8c61\u8fde\u7740\uff0c\u5c31\u4e0d\u4f1a\u88ab\u6536\u96c6\u3002&nbsp;&nbsp;&nbsp; \u800cWeakReference\u5c31\u662f\u771f\u6b63\u610f\u4e49\u4e0a\u7684C++\u6307\u9488\uff0c\u53ea\u662f\u5355\u7eaf\u7684\u6307\u5411\u4e00\u4e2a\u5bf9\u8c61\uff0c\u800c\u4e0d\u4f1a\u5f71\u54cd\u5bf9\u8c61\u7684\u5f15\u7528\u8ba1\u6570\u3002&nbsp;&nbsp;&nbsp; \u800cSoftReference\u66f4\u7279\u522b\uff0c\u5728\u5185\u5b58\u8db3\u591f\u65f6\uff0c\u5bf9\u8c61\u4f1a\u56e0\u4e3aSoftReference\u7684\u5b58\u5728\u800c\u4e0d\u88ab\u6536\u96c6\uff0c\u4f46\u5185\u5b58\u4e0d\u8db3\u65f6\uff0c\u5bf9\u8c61\u5c31\u8fd8\u662f\u4f1a\u88ab\u6536\u96c6\uff0c\u600e\u4e48\u770b\u90fd\u662f\u505a\u7b80\u5355\u7f13\u5b58\u7684\u6599\u5b50\u3002\u4ee3\u7801\u5982\u4e0b\uff1a &nbsp;&nbsp;Foo&nbsp;foo&nbsp;=&nbsp;new&nbsp;Foo();&nbsp;&nbsp;&nbsp;SoftReference&nbsp;sr=&nbsp;new&nbsp;SoftReference(foo);&nbsp;&nbsp;&nbsp;Foo&nbsp;bar&nbsp;=&nbsp;&nbsp;sr.get();&nbsp; &nbsp; &hellip; <a href=\"https:\/\/www.strongd.net\/?p=507\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">\u7f16\u5199\u5bf9GC\u53cb\u597d\uff0c\u53c8\u4e0d\u6cc4\u6f0f\u7684\u4ee3\u7801<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[88],"class_list":["post-507","post","type-post","status-publish","format-standard","hentry","category-java","tag-gc"],"_links":{"self":[{"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/posts\/507","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.strongd.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=507"}],"version-history":[{"count":1,"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/posts\/507\/revisions"}],"predecessor-version":[{"id":863,"href":"https:\/\/www.strongd.net\/index.php?rest_route=\/wp\/v2\/posts\/507\/revisions\/863"}],"wp:attachment":[{"href":"https:\/\/www.strongd.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=507"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.strongd.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=507"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.strongd.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=507"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}