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60ms，如下","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/1d/1d2385cf63d8a2f401a750c12e04279e.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"size","attrs":{"size":10}}],"text":"第3次是非高峰时段，Minor GC 耗时 0.00s + remark耗时 0.04s = 0.04s = 40ms，如下","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/ab/ab6b54087d417a089c210191406cab36.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"size","attrs":{"size":10}},{"type":"strong","attrs":{}}],"text":"所以，3次Minor GC + remark耗时的平均耗时 < 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时长，通过调整这两个参数：","attrs":{}}]},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"-XX:CMSMaxAbortablePrecleanTime=xxx\n-XX:CMSScheduleRemarkEdenPenetration=xxx","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"size","attrs":{"size":10}}],"text":"调整为多少的一个判断标准是：abortable preclean阶段结束时，新生代的空间占用不能大于某个参考值。 在前面第一次调优后，新生代（YG）占用181.274M，remark耗时80ms；新生代（YG）占用773.427M时，remark耗时910ms。所以这个参考值可以是300M。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"size","attrs":{"size":10}},{"type":"strong","attrs":{}}],"text":"而如果新生代增长过快，像这次调优应用2秒内就能用光2G新生代堆空间的，就只能通过CMSScavengeBeforeRemark做一次Minor GC了","attrs":{}},{"type":"text","marks":[{"type":"size","attrs":{"size":10}}],"text":"。","attrs":{}}]}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"size","attrs":{"size":10}},{"type":"strong","attrs":{}}],"text":" 增加CMSScavengeBeforeRemark参数开启remark前进行Minor GC的尝试","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"size","attrs":{"size":10}},{"type":"strong","attrs":{}}],"text":" 虽然官方说明这个增加这个参数是尝试进行Minor GC，不一定会进行。但实际使用起来，几乎每次remark前都会Minor GC。","attrs":{}}]}]}