{"id":170,"date":"2018-03-12T14:00:23","date_gmt":"2018-03-12T06:00:23","guid":{"rendered":"http:\/\/www.max-shu.com\/blog\/?p=170"},"modified":"2018-03-12T14:00:23","modified_gmt":"2018-03-12T06:00:23","slug":"hadoop%e6%80%a7%e8%83%bd%e6%a8%a1%e5%9e%8b%ef%bc%883%ef%bc%89","status":"publish","type":"post","link":"http:\/\/www.max-shu.com\/blog\/?p=170","title":{"rendered":"Hadoop\u6027\u80fd\u6a21\u578b\uff083\uff09"},"content":{"rendered":"<p><span style=\"font-size: medium;\"><b>2.3 Merge\u9636\u6bb5\u6a21\u578b<\/b><\/span><\/p>\n<p>merge\u9636\u6bb5\u7684\u76ee\u6807\u662f\u5408\u5e76\u6240\u6709spill\u6587\u4ef6\u5230\u4e00\u4e2a\u5355\u4e00\u7684\u8f93\u51fa\u6587\u4ef6\uff0c\u5199\u5165\u672c\u5730\u78c1\u76d8\u3002\u591a\u4e8e\u4e00\u4e2aspill\u6587\u4ef6\u7684\u65f6\u5019\u5c31\u4f1a\u53d1\u751fmerge\uff0c\u4e5f\u8bb8\u4f1a\u6709\u591a\u6b21merge\uff0c\u53d6\u51b3\u4e8epSortFactor\u53c2\u6570\u3002\u5b9a\u4e49\u4e00\u6b21merge\u6700\u591a\u5408\u5e76pSortFactor\u51b3\u5b9a\u7684spill\u6587\u4ef6\u6570\u3002\u5b9a\u4e49\u4e00\u8f6emerge\u4e3a\u4e00\u6b21\u6216\u591a\u6b21merge\uff0c\u5728spill\u9636\u6bb5\u518d\u4ea7\u751fspill\u6587\u4ef6\u6216\u524d\u4e00\u8f6espill\u518d\u4ea7\u751fspill\u6587\u4ef6\u7684\u8bdd\u5c31\u4f1a\u6709\u591a\u8f6emerge\u51fa\u73b0\u3002\u4f8b\u5982\uff0c\u5047\u5b9anumSpills=30\u3001pSortFactor\uff1d10\uff0c\u56e0\u6b643\u4e2amerge\u4f1a\u6267\u884c\uff0c\u5efa\u7acb\u4e09\u4e2a\u65b0\u6587\u4ef6\uff0c\u8fd9\u662f\u7b2c\u4e00\u8f6e\uff0c\u63a5\u7740\uff0c\u4e09\u4e2a\u65b0\u6587\u4ef6\u5c06merge\u5230\u4e00\u8d77\uff0c\u8fd9\u662f\u7b2c\u4e8c\u8f6e\uff0c\u4e5f\u662f\u6700\u540e\u4e00\u8f6e\u3002<\/p>\n<p>\u5982\u679c\u6700\u540e\u4e00\u6b21\u9700\u8981\u5408\u5e76\u7684spill\u6570\u91cf\u5927\u4e8e\u7b49\u4e8epNumSpillsForComb\uff0ccombiner\u9700\u8981\u518d\u6b21\u4f7f\u7528\u3002\u8fdb\u4e00\u6b65\uff0c\u6211\u4eec\u628a\u4e2d\u95f4merge\u548c\u6700\u540emerge\u5206\u5f00\u3002\u4e2d\u95f4merge\uff0c\u6211\u4eec\u8ba1\u7b97\u5355\u4e2aspill\u5c06\u88ab\u8bfb\u591a\u5c11\u6b21\u3002<\/p>\n<p>\u63a5\u4e0b\u6765\u7684\u90e8\u5206\u5047\u5b9anumSpills&lt;=pSortFactor\uff0c\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4e3a\u4e86\u8ba1\u7b97\u5728\u4e2d\u95f4merge\u9636\u6bb5spills\u6570\u91cf\uff0c\u6211\u4eec\u4f7f\u7528\u4eff\u771f\u65b9\u6cd5\u3002<\/p>\n<p>\u7b2c\u4e00\u6b21merge\u662f\u7edf\u4e00\u7684\uff0c\u56e0\u4e3ahadoop\u4f1a\u8ba1\u7b97\u4f18\u5316spill\u6587\u4ef6\u6570\u7528\u6765\u5408\u5e76\uff0c\u4ee5\u4fbf\u6240\u6709merge\u90fd\u521a\u597d\u662fpSortFactor\u4e2a\u6587\u4ef6\u3002<br \/>\n\u65e2\u7136Reduce\u4e5f\u4f1a\u5305\u542b\u4e00\u4e2a\u7c7b\u4f3c\u7684Merge\u9636\u6bb5\uff0c\u5b9a\u4e49\u4e09\u4e2a\u516c\u5f0f\uff0c\u4e4b\u540e\u53ef\u4ee5\u91cd\u7528\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-171\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-17.png\" alt=\"\" width=\"898\" height=\"247\" \/><\/p>\n<p>\u7b2c\u4e00\u6b21merge\u671f\u95f4spill\u6587\u4ef6\u6570\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-172\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-18.png\" alt=\"\" width=\"897\" height=\"37\" \/><br \/>\n\u4e2d\u95f4merge\u671f\u95f4spill\u6587\u4ef6\u6570\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-173\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-19.png\" alt=\"\" width=\"897\" height=\"31\" \/><br \/>\nmerge\u603b\u6570\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-174\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-20.png\" alt=\"\" width=\"911\" height=\"116\" \/><br \/>\n\u6700\u540e\u4e00\u8f6emerge\u7684spill\u6587\u4ef6\u6570\uff08\u7b2c\u4e00\u6b21\uff0b\u4e2d\u95f4\uff0b\u4f59\u4e0b\u7684spill\u6587\u4ef6\uff09\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-175\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-21.png\" alt=\"\" width=\"897\" height=\"29\" \/><br \/>\n\u603b\u7684spill\u8fc7\u7684\u8bb0\u5f55\u6570\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-176\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-22.png\" alt=\"\" width=\"1013\" height=\"64\" \/><br \/>\n\u6700\u7ec8map\u8f93\u51fa\u5927\u5c0f\u548ck\uff0dv\u5bf9\u6570\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-177\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-23.png\" alt=\"\" width=\"899\" height=\"338\" \/><br \/>\n\u8be5\u9636\u6bb5\u7684\u6d88\u8017\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-178\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-24.png\" alt=\"\" width=\"899\" height=\"542\" \/><\/p>\n<p><span style=\"font-size: medium;\"><b>2.4 \u6574\u4e2amap\u9636\u6bb5\u6a21\u578b<\/b><\/span><br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-179\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-25.png\" alt=\"\" width=\"954\" height=\"185\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>2.3 Merge\u9636\u6bb5\u6a21\u578b merge\u9636\u6bb5\u7684\u76ee\u6807\u662f\u5408\u5e76\u6240\u6709spill\u6587\u4ef6\u5230\u4e00\u4e2a\u5355\u4e00\u7684\u8f93\u51fa\u6587\u4ef6\uff0c\u5199\u5165\u672c\u5730\u78c1\u76d8\u3002\u591a 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