{"id":47635,"date":"2023-12-11T15:12:30","date_gmt":"2023-12-11T07:12:30","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=47635"},"modified":"2023-12-11T15:12:30","modified_gmt":"2023-12-11T07:12:30","slug":"%e4%bb%8e%e5%ba%94%e7%94%a8%e7%a8%8b%e5%ba%8f%e8%a7%92%e5%ba%a6%e8%bf%9b%e8%a1%8c%e4%bc%98%e5%8c%96-4","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/12\/11\/%e4%bb%8e%e5%ba%94%e7%94%a8%e7%a8%8b%e5%ba%8f%e8%a7%92%e5%ba%a6%e8%bf%9b%e8%a1%8c%e4%bc%98%e5%8c%96-4\/","title":{"rendered":"\u4ece\u5e94\u7528\u7a0b\u5e8f\u89d2\u5ea6\u8fdb\u884c\u4f18\u5316"},"content":{"rendered":"

“`” \u89e3\u7b54\uff1a<\/p>\n

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\uff082\uff09 \u4e3ajob\u6dfb\u52a0\u4e00\u4e2aCombiner<\/p>\n

\u4e3ajob\u6dfb\u52a0\u4e00\u4e2acombiner\u53ef\u4ee5\u5927\u5927\u51cf\u5c11shuffle\u9636\u6bb5\u4ecemap task\u62f7\u8d1d\u7ed9\u8fdc\u7a0breduce task\u7684\u6570\u636e\u91cf\u3002\u4e00\u822c\u800c\u8a00\uff0ccombiner\u4e0ereducer\u76f8\u540c\u3002<\/p>\n

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Text\u5bf9\u8c61\u4f7f\u7528\u8d77\u6765\u5f88\u65b9\u4fbf\uff0c\u4f46\u5b83\u5728\u7531\u6570\u503c\u8f6c\u6362\u5230\u6587\u672c\u6216\u662f\u7531UTF8\u5b57\u7b26\u4e32\u8f6c\u6362\u5230\u6587\u672c\u65f6\u90fd\u662f\u4f4e\u6548\u7684\uff0c\u4e14\u4f1a\u6d88\u8017\u5927\u91cf\u7684CPU\u65f6\u95f4\u3002\u5f53\u5904\u7406\u90a3\u4e9b\u975e\u6587\u672c\u7684\u6570\u636e\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528\u4e8c\u8fdb\u5236\u7684Writable\u7c7b\u578b\uff0c\u5982IntWritable\uff0c FloatWritable\u7b49\u3002\u4e8c\u8fdb\u5236writable\u597d\u5904\uff1a\u907f\u514d\u6587\u4ef6\u8f6c\u6362\u7684\u6d88\u8017\uff1b\u4f7fmap task\u4e2d\u95f4\u7ed3\u679c\u5360\u7528\u66f4\u5c11\u7684\u7a7a\u95f4\u3002<\/p>\n

\uff084\uff09 \u91cd\u7528Writable\u7c7b\u578b<\/p>\n

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<pre><code>public void map(…) {<\/p>\n

\u2026<\/p>\n

for (String word : words) {<\/p>\n

output.collect(new Text(word), new IntWritable(1));
\n }<\/p>\n

}<\/p>\n

<\/code><\/pre><\/p>\n

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<pre><code>class MyMapper \u2026 {<\/p>\n

Text wordText = new Text();<\/p>\n

IntWritable one = new IntWritable(1);<\/p>\n

public void map(…) {<\/p>\n

for (String word: words) {<\/p>\n

wordText.set(word);<\/p>\n

output.collect(wordText, one);<\/p>\n

}
\n }<\/p>\n

}<\/p>\n

<\/code><\/pre><\/p>\n

\u00a0<\/p>\n

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<pre><code> "“`
\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"

“`” \u89e3\u7b54\uff1a \uff081\uff09 \u907f\u514d\u4e0d\u5fc5\u8981\u7684reduce\u4efb\u52a1 \u5982\u679cmapreduce\u7a0b\u5e8f\u4e2dre […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-47635","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47635","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=47635"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47635\/revisions"}],"predecessor-version":[{"id":47636,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47635\/revisions\/47636"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=47635"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=47635"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=47635"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}