{"id":192,"date":"2018-03-12T14:07:03","date_gmt":"2018-03-12T06:07:03","guid":{"rendered":"http:\/\/www.max-shu.com\/blog\/?p=192"},"modified":"2018-03-12T14:07:03","modified_gmt":"2018-03-12T06:07:03","slug":"hadoop%e6%80%a7%e8%83%bd%e6%a8%a1%e5%9e%8b%ef%bc%885%ef%bc%89","status":"publish","type":"post","link":"http:\/\/www.max-shu.com\/blog\/?p=192","title":{"rendered":"Hadoop\u6027\u80fd\u6a21\u578b\uff085\uff09"},"content":{"rendered":"<p>\u6574\u4e2ashuffle\u9636\u6bb5\u7684\u6d88\u8017\u662f\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-193\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-35.png\" alt=\"\" width=\"903\" height=\"459\" \/><\/p>\n<p><span style=\"font-size: medium;\"><b>3.2 Merge\u9636\u6bb5\u6a21\u578b<\/b><\/span><\/p>\n<p>\u6574\u4e2amap\u8f93\u51fa\u62f7\u8d1d\u5230\u5185\u5b58\u548c\uff08\u6216\uff09\u78c1\u76d8\u4e4b\u540e\uff0c\u6392\u5e8f\u5408\u5e76\u9636\u6bb5\u5f00\u59cb\uff0c\u8be5\u9636\u6bb5\u5c06\u5408\u5e76\u6240\u6709\u7684\u6570\u636e\u5230\u5355\u4e2a\u6d41\uff0c\u4ee5\u4fbfreducer\uff0c\u8ddfmap\u5408\u5e76\u9636\u6bb5\u7c7b\u4f3c\uff0c\u8be5\u9636\u6bb5\u4e5f\u53ef\u4ee5\u6709\u591a\u8f6e\uff0c\u4f46\u662f\u6700\u540e\u5408\u5e76\u4e4b\u540e\uff0c\u4e0d\u5efa\u7acb\u8f93\u51fa\u6587\u4ef6\uff0c\u800c\u662f\u628a\u6570\u636e\u53d1\u9001\u7ed9reducer\u3002<\/p>\n<p>shuffle\u9636\u6bb5\u751f\u6210\u4e86\u78c1\u76d8\u4e0a\u7684\u5408\u5e76\u6216\u975e\u5408\u5e76shuffle\u6587\u4ef6\uff0c\u6216\u8005\u5728\u5185\u5b58\u4e2d\u7684\u5206\u7247\u3002\u968f\u540e\u7684\u5408\u5e76\u5206\u4e3a\u4e09\u6b65\u3002<\/p>\n<p>\u7b2c\u4e00\u6b65\uff1a\u4e00\u4e9b\u5206\u7247\u4e5f\u8bb8\u4ece\u5185\u5b58\u88ab\u5408\u5e76\u5230\u4e00\u4e2a\u5355\u4e2a\u7684shuffle\u6587\u4ef6\uff0c\u4e3a\u4e86\u6ee1\u8db3pReducerInBufPerc\u7684\u5185\u5b58\u9650\u5236\uff08\u8be5\u53c2\u6570\u6307\u5b9a\u4e86reducer\u4e4b\u524d\u7684\u5185\u5b58\u5206\u7247\u6570\u91cf\uff09\u3002<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-194\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-36.png\" alt=\"\" width=\"897\" height=\"351\" \/><br \/>\n\u53ea\u6709\u78c1\u76d8\u4e0a\u7684shuffle\u6587\u4ef6\u6570\u5c0f\u4e8epSortFactor\u65f6\uff0c\u4e0a\u9762\u7684\u5408\u5e76\u624d\u53d1\u751f\uff0c\u5047\u5982\u4e0d\u5c0f\u4e8e\u7684\u8bdd\uff0c\u5219\u8ddf\u5185\u5b58\u4e2d\u7684\u5206\u7247\u4e00\u8d77\u8fdb\u884c\u5408\u5e76\u3002<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-195\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-37.png\" alt=\"\" width=\"896\" height=\"543\" \/><\/p>\n<p>\u7b2c\u4e8c\u6b65\uff1a\u78c1\u76d8\u4e0a\u7684\u6587\u4ef6\u6709\u53ef\u80fd\u7ecf\u8fc7\u591a\u8f6emerge\uff08\u7c7b\u4f3c\u4e8emap\u4efb\u52a1\u5904\u7406\uff0c\u8be5\u6b65\u53ea\u6709\u5728numFilesOnDisk&gt;0\uff08\u5373filesToMergeStep2&gt;0\uff09\u624d\u4f1a\u53d1\u751f\uff09\u3002\u4e2d\u95f4\u8bfb\u5165\u7684\u6570\u91cf\u662f\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-196\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-38.png\" alt=\"\" width=\"897\" height=\"29\" \/><br \/>\n\u8ddfmap\u4efb\u52a1\u4e0d\u540c\u7684\u662f\u5408\u5e76\u6587\u4ef6\u7684\u5927\u5c0f\u4e0d\u540c\uff0c\u53ef\u4ee5\u8ba1\u7b97\uff1a<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-197\" src=\"http:\/\/www.max-shu.com\/blog\/wp-content\/uploads\/2018\/03\/\u4e0b\u8f7d-39.png\" alt=\"\" width=\"900\" height=\"405\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6574\u4e2ashuffle\u9636\u6bb5\u7684\u6d88\u8017\u662f\uff1a 3.2 Merge\u9636\u6bb5\u6a21\u578b \u6574\u4e2amap\u8f93\u51fa\u62f7\u8d1d\u5230\u5185\u5b58\u548c\uff08\u6216\uff09\u78c1\u76d8\u4e4b\u540e\uff0c\u6392\u5e8f\u5408 &hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[63],"tags":[80,123,122,120,121],"class_list":["post-192","post","type-post","status-publish","format-standard","hentry","category-63","tag-hadoop","tag-hdfs","tag-mapreduce","tag-120","tag-121"],"views":1540,"_links":{"self":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/192","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=192"}],"version-history":[{"count":1,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/192\/revisions"}],"predecessor-version":[{"id":198,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/192\/revisions\/198"}],"wp:attachment":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=192"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=192"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=192"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}