{"id":1354,"date":"2020-11-19T20:00:20","date_gmt":"2020-11-19T12:00:20","guid":{"rendered":"https:\/\/www.specialwu.com\/?p=1354"},"modified":"2023-04-02T13:03:34","modified_gmt":"2023-04-02T05:03:34","slug":"%e9%9d%a2%e8%af%95%e9%a2%98%e8%ae%b0%e5%bd%95","status":"publish","type":"post","link":"http:\/\/www.specialwu.com\/?p=1354","title":{"rendered":"\u4e00\u4e9b\u95ee\u9898\u8bb0\u5f55"},"content":{"rendered":"<blockquote><p>\n  \u5728\u8fd0\u7528\u5927\u6570\u636e\u6280\u672f\u5904\u7406\u6570\u636e\u8fc7\u7a0b\u4e2d\u6d89\u53ca\u5230\u5982\u4e0b\u51e0\u4e2a\u65b9\u9762\u7684\u95ee\u9898\n<\/p><\/blockquote>\n<ol>\n<li>\u5728\u4f20\u8f93\u6570\u636e\u65f6\u600e\u4e48\u628a\u6570\u636e\u5b8c\u6574\u7684\u62ff\u8fc7\u6765\u662f\u9996\u8981\u89e3\u51b3\u7684\u95ee\u9898<\/li>\n<\/ol>\n<p>\u8fd9\u5176\u4e2d\u6d89\u53ca\uff1aflume\u600e\u4e48\u4fdd\u8bc1\u65ad\u70b9\u7eed\u4f20\uff0ckafka\u5728\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u53d1\u751f\u6570\u636e\u79ef\u538b\u600e\u4e48\u89e3\u51b3\uff1b<\/p>\n<ol start=\"2\">\n<li>\u5728\u5b58\u50a8\u6570\u636e\u65f6\u600e\u4e48\u4f7f\u5f97\u6570\u636e\u80fd\u5b58\u7684\u4e0b\u662f\u9996\u8981\u89e3\u51b3\u7684\u95ee\u9898<\/li>\n<\/ol>\n<p>\u8fd9\u5176\u4e2d\u6d89\u53ca\uff1a\u5982\u679chdfs\u4e0anamenode\u8282\u70b9\u6302\u6389\u600e\u4e48\u89e3\u51b3\uff0c\u4ee5\u53ca\u6302\u6389\u540e\u600e\u4e48\u5feb\u901f\u6062\u590d\uff1b<\/p>\n<ol start=\"3\">\n<li>\u5728\u5904\u7406\u6570\u636e\u65f6\u67d0\u53f0\u673a\u5668\u627f\u62c5\u538b\u529b\u8fdc\u5927\u4e8e\u5176\u4ed6\u673a\u5668\uff0c\u600e\u4e48\u4f7f\u5f97\u8ba1\u7b97\u6548\u7387\u6700\u9ad8\u8fd9\u662f\u6211\u4eec\u9996\u8981\u89e3\u51b3\u7684\u95ee\u9898<\/li>\n<\/ol>\n<p>\u8fd9\u5176\u4e2d\u6d89\u53ca\uff1amapreduce\u4ee5\u53caspark\u600e\u4e48\u5904\u7406\u6570\u636e\u503e\u659c\u8fd9\u4e2a\u95ee\u9898\uff1b<\/p>\n<blockquote><p>\n  HDFS\u4e0a\u4f20\u6587\u4ef6\u65f6\u662f\u5148\u628a\u6574\u4e2a\u6587\u4ef6\u8bfb\u5230\u5185\u5b58\u4e2d\uff0c\u7136\u540e\u518d\u5206\u5757\uff0c\u8fd8\u662f\u8fb9\u8bfb\uff0c\u8fb9\u5206\u5757;HDFS\u5982\u4f55\u5224\u65ad\u4e00\u4e2a\u6587\u4ef6\u7684\u5927\u5c0f\uff08\u4ed6\u600e\u77e5\u9053\u8fd9\u4e2a\u6587\u4ef6\u662f100M\u8fd8\u662f200M\uff09\n<\/p><\/blockquote>\n<p>hdfs\u7684\u5ba2\u6237\u7aef\u5728\u8bfb\u53d6\u6570\u636e\u65f6\u4f1a\u628a\u6570\u636e\u6309\u7167\u9884\u5148\u8bbe\u597d\u7684\u53c2\u6570\uff0c\u5206\u6210\u4e00\u4e2a\u5757\uff0c\u8fd9\u4e2a\u5757\u662f\u8fb9\u8bfb\u8fb9\u8fdb\u884c\u62c6\u5206\u7684\uff0c\u5982\u679c\u52a0\u5728\u5185\u5b58\u4e2d\uff0c\u90a3\u4e48\u673a\u5668\u5f88\u5feb\u5c31\u5b95\u673a\u4e86\uff1b<\/p>\n<blockquote><p>\n  HDFS HA\u6a21\u5f0f\u4e2djounalnode\u600e\u4e48\u786e\u5b9a\u54ea\u53f0\u673a\u5668\u662fnamenode\n<\/p><\/blockquote>\n<p>\u5728\u521a\u5f00\u59cb\u542f\u52a8\u65f6\uff0c\u4f1a\u6709\u4e2a\u9884\u5148\u8bbe\u7f6e\u597d\u7684namenode,\u542f\u52a8\u65f6\u6709\u4e2aActive namenode \uff0cStandby namenode<\/p>\n<blockquote><p>\n  \u5728HDFS\u4e0a\u4f60\u662f\u600e\u4e48\u5904\u7406\u5927\u91cf\u7684\u5c0f\u6587\u4ef6\u7684\n<\/p><\/blockquote>\n<p>hdfs\u5728\u8bbe\u8ba1\u4e4b\u521d\u5c31\u51b3\u5b9a\u4e86\uff0c\u5b83\u4e0d\u64c5\u957f\u5b83\u7ba1\u7406\u5927\u91cf\u7684\u5c0f\u6587\u4ef6\uff0c\u5c0f\u6587\u4ef6\u8fc7\u591a\u9996\u5148\u5bfc\u81f4namenode\u5185\u5b58\u8fc7\u5927\uff0c\u5176\u6b21\u627e\u8fd9\u4e2a\u6587\u4ef6\u7684\u65f6\u95f4\u5927\u4e8e\u4f20\u8f93\u8fd9\u4e2a\u6587\u4ef6\u7684\u65f6\u95f4\uff1b\u56e0\u6b64\u5982\u679c\u6839\u636e\u4e1a\u52a1\u903b\u8f91\u672c\u8eab\u6765\u8bf4\uff0c\u5982\u679c\u4e00\u76f4\u5904\u7406\u7684\u662f\u5c0f\u6587\u4ef6\u90a3\u4e48\u53ef\u4ee5\u8003\u8651<code>dfs.block.size<\/code>\u8c03\u6574\u5757\u5927\u5c0f\uff0c\u4f46\u8fd9\u662f\u4e0b\u4e0b\u4e4b\u7b56\uff1b<br \/>\n<code>\u65b9\u6cd5\u4e00<\/code>\uff1a\u91c7\u7528HAR\uff08Hadoop Archives\uff09\u7684\u5f52\u6863\u65b9\u5f0f\u3002HAR\u4e3a\u6784\u5efa\u5728\u5176\u5b83\u6587\u4ef6\u7cfb\u7edf\u4e0a\u7528\u4e8e\u6587\u4ef6\u5b58\u6863\u7684\u6587\u4ef6\u7cfb\u7edf\uff0c\u901a\u5e38\u5c06hdfs\u4e2d\u7684\u591a\u4e2a\u6587\u4ef6\u6253\u5305\u6210\u4e00\u4e2a\u5b58\u6863\u6587\u4ef6\uff0c\u51cf\u5c11namenode\u5185\u5b58\u7684\u4f7f\u7528\uff0c\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528hadoop archive\u547d\u4ee4\u521b\u5efaHAR\u6587\u4ef6\u3002\u521b\u5efaHAR\u7684\u8fc7\u7a0b\u662f\u5728\u8fd0\u884c\u4e00\u4e2amr\u4f5c\u4e1a\u3002har\u5728\u5bf9\u5c0f\u6587\u4ef6\u8fdb\u884c\u5b58\u6863\u540e\uff0c\u539f\u6587\u4ef6\u4e0d\u4f1a\u88ab\u5220\u9664\uff0c\u4e14\u521b\u5efa\u4e4b\u540e\u4e0d\u80fd\u6539\u53d8\uff0c\u6587\u4ef6\u540d\u4e2d\u4e5f\u4e0d\u80fd\u6709\u7a7a\u683c\u5b58\u5728\uff0c\u5426\u5219\u4f1a\u62a5\u5f02\u5e38\u3002<br \/>\n<code>\u65b9\u6cd5\u4e8c<\/code>:\u5f00\u542fJVM\u91cd\u7528;JVM\u91cd\u7528\u53ef\u4ee5\u4f7f\u5f97JVM\u5b9e\u4f8b\u5728\u540c\u4e00\u4e2ajob\u4e2d\u91cd\u65b0\u4f7f\u7528N\u6b21\uff0cN\u7684\u503c\u53ef\u4ee5\u5728hadoop\u7684mapred-site.xml\u6587\u4ef6\u4e2d\u8fdb\u884c\u914d\u7f6e\uff0c\u901a\u5e38\u572810-20\u4e4b\u95f4\u3002\u5982\u679c\u6ca1\u6709\u5c0f\u6587\u4ef6\uff0c\u4e0d\u8981\u5f00\u542fJVM\u91cd\u7528\uff0c\u56e0\u4e3a\u4f1a\u4e00\u76f4\u5360\u7528\u4f7f\u7528\u5230\u7684task\u5361\u69fd\uff0c\u76f4\u5230\u4efb\u52a1\u5b8c\u6210\u624d\u91ca\u653e<br \/>\n<code>mapred-site.xml<\/code><\/p>\n<pre><code class=\"language-java line-numbers\">&lt;property&gt;\n\u3000\u3000&lt;name&gt;mapreduce.job.jvm.numtasks&lt;\/name&gt;\n\u3000\u3000&lt;value&gt;10&lt;\/value&gt;\n\u3000\u3000&lt;description&gt;How many tasks to run per jvm,if set to -1 ,there is no limit&lt;\/description&gt;\n&lt;\/property&gt;\n<\/code><\/pre>\n<blockquote><p>\n  Kafa\u7684\u9ad8\u541e\u5410\u91cf\u662f\u600e\u4e48\u5b9e\u73b0\u7684\uff08\u5c31\u5355\u53f0\u673a\u5668\u672c\u8eab\u6765\u8bf4\uff09\n<\/p><\/blockquote>\n<ol>\n<li><strong>\u987a\u5e8f\u5199\u5165<\/strong><br \/>\n\u5728\u786c\u76d8\u4e0a\u5199\u4e00\u4e2a\u6587\u4ef6\u7684\u65f6\u9700\u8981\u5bfb\u9053\u627e\u51fa\u4e00\u4e2a\u5b58\u50a8\u4f4d\u7f6e\uff0c\u5982\u8fc7\u5199\u5165\u6587\u4ef6\u8f83\u591a\uff0c\u5219\u9700\u8981\u9891\u7e41\u7684\u901a\u8fc7\u523a\u5934\u627e\u5230\u5b58\u50a8\u4f4d\u7f6e\u975e\u5e38\u8017\u65f6\uff0c\u5199\u5165\u901f\u5ea6\u56e0\u6b64\u964d\u4f4e\u3002Kafka\u4f1a\u5c06\u6570\u636e\u987a\u5e8f\u63d2\u5165\u5230\u6587\u4ef6\u672b\u5c3e\uff0c\u6d88\u8d39\u8005\u7aef\u901a\u8fc7\u63a7\u5236\u504f\u79fb\u91cf\u6765\u8bfb\u53d6\u6d88\u606f\uff0c\u8fd9\u6837\u505a\u4f1a\u5bfc\u81f4\u6570\u636e\u65e0\u6cd5\u5220\u9664\uff0c\u65f6\u95f4\u4e00\u957f\uff0c\u78c1\u76d8\u7a7a\u95f4\u4f1a\u6ee1\u3002<br \/>\n\u9488\u5bf9\u8fd9\u79cd\u60c5\u51b5\uff0ckafka\u63d0\u4f9b\u4e862\u79cd\u7b56\u7565\u6765\u5220\u9664\u6570\u636e\uff1a\u57fa\u4e8e\u65f6\u95f4\u5220\u9664\u548c\u57fa\u4e8epartition\u6587\u4ef6\u7684\u5927\u5c0f\u5220\u9664\u3002<\/li>\n<li><strong>Memory Mapped Files<\/strong><br \/>\n\u6620\u5c04\u78c1\u76d8\u7684\u6587\u4ef6\u5230\u5185\u5b58\uff1a\u628a\u4e00\u4e2a\u6587\u4ef6\u6620\u5c04\u5230\u4e00\u4e2a\u8fdb\u7a0b\u5730\u5740\uff0c\u7136\u540e\u901a\u8fc7\u64cd\u4f5c\u5185\u5b58\u6765\u4fee\u6539\u78c1\u76d8\u6570\u636e\uff1b<br \/>\n\u6709\u5982\u4e0b\u51e0\u79cd\u4f18\u52bf<\/li>\n<\/ol>\n<p>&#8211; \u7528\u6237\u8fdb\u7a0b\u628a\u6587\u4ef6\u6570\u636e\u5f53\u5185\u5b58\u6570\u636e\uff0c\u65e0\u9700\u8c03\u7528read()\u6216write()<br \/>\n&#8211; \u5f53\u7528\u6237\u8fdb\u7a0b\u63a5\u89e6\u5230\u6620\u5c04\u5185\u5b58\u7a7a\u95f4\uff0c\u4f1a\u81ea\u52a8\u4ea7\u751f\u9875\u9519\u8bef\uff0c\u4ece\u800c\u5c06\u6587\u4ef6\u6570\u636e\u4ece\u78c1\u76d8\u8bfb\u5230\u5185\u5b58\uff1b\u82e5\u7528\u6237\u7a7a\u95f4\u8fdb\u7a0b\u4fee\u6539\u4e86\u5185\u5b58\u9875\u6570\u636e\uff0c\u76f8\u5173\u9875\u4f1a\u81ea\u52a8\u6807\u8bb0\u5e76\u5237\u65b0\u5230\u78c1\u76d8\uff0c\u6587\u4ef6\u88ab\u66f4\u65b0<br \/>\n&#8211; \u64cd\u4f5c\u7cfb\u7edf\u7684\u865a\u62df\u5185\u5b58\u5bf9\u5185\u5b58\u9875\u8fdb\u884c\u9ad8\u901f\u7f13\u5b58\uff0c\u81ea\u52a8\u6839\u636e\u7cfb\u7edf\u8d1f\u8f7d\u8fdb\u884c\u5185\u5b58\u7ba1\u7406<br \/>\n&#8211; \u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u7684\u6570\u636e\u603b\u662f\u4e00\u4e00\u5bf9\u5e94\uff0c\u65e0\u9700\u6267\u884c\u7f13\u51b2\u533a\u62f7\u8d1d<br \/>\n&#8211; \u5927\u6570\u636e\u7684\u6587\u4ef6\u4f7f\u7528\u6620\u5c04\uff0c\u65e0\u9700\u6d88\u8017\u5927\u91cf\u5185\u5b58\u5373\u53ef\u8fdb\u884c\u6570\u636e\u62f7\u8d1d<\/p>\n<p>\u521b\u5efa\u4e00\u4e2a\u5185\u5b58\u6620\u5c04\u6587\u4ef6<\/p>\n<pre><code class=\"language-java line-numbers\">RandomAccessFile raf = new RandomAccessFile(\"test.txt\", \"rw\");\nFileChannel fc = raf.getChannel();\n\/\/\u5c06test.txt\u6587\u4ef6\u6240\u6709\u6570\u636e\u6620\u5c04\u5230\u865a\u62df\u5185\u5b58\uff0c\u5e76\u53ea\u8bfb\nMappedByteBuffer mbuff = fc.map(MapMode.READ_ONLY, 0, fc.size());\n<\/code><\/pre>\n<ul>\n<li>\u7f3a\u70b9\u53ca\u89e3\u51b3\u529e\u6cd5<br \/>\n\u4f7f\u7528\u5185\u5b58\u6620\u5c04\u7684\u8bdd\u5982\u679c\u673a\u5668\u5b95\u673a\uff0c\u6570\u636e\u5219\u4f1a\u4e22\u5931\uff0c\u90a3\u4e48Kafka\u63d0\u4f9b\u4e86produce.type\u53c2\u6570\u6765\u63a7\u5236\u662f\u5426\u4e3b\u52a8\u7684\u8fdb\u884c\u5237\u65b0\uff0c\u5982\u679ckafka\u5199\u5165\u5230mmp\u540e\u7acb\u5373flush\u518d\u8fd4\u56de\u7ed9\u751f\u4ea7\u8005\u5219\u4e3a\u540c\u6b65\u6a21\u5f0f\uff0c\u53cd\u4e4b\u4e3a\u5f02\u6b65\u6a21\u5f0f\u3002<\/li>\n<\/ul>\n<ol start=\"3\">\n<li><strong>\u96f6\u62f7\u8d1d<\/strong><\/li>\n<\/ol>\n<p>&#8211; \u9996\u5148\u8bf4\u4e0b\u4f20\u7edf\u7684\u6570\u636e\u4f20\u8f93\u5f62\u5f0f<br \/>\n\u4f20\u8f93\u8fc7\u7a0b\u9996\u5148\u6709\u8fd9\u4e48\u51e0\u4e2a\u90e8\u5206\uff0c\u5e94\u7528\u7a0b\u5e8f->cpu->DMA(Direct Memory Access)->Disk<br \/>\n\u4ee5\u8bfb\u6570\u636e\u4e3e\u4f8b<br \/>\n1. \u5e94\u7528\u7a0b\u5e8f\u8bfb\u53d6\u6570\u636e\u9996\u5148\u8c03\u53d6read()\u51fd\u6570\u4ece\u7528\u6237\u6001\u8f6c\u5316\u5185\u6838\u6001<br \/>\n2. DMA\u4ece\u78c1\u76d8\u7f13\u51b2\u533a\u62f7\u8d1d\u6570\u636e\u5230\u5185\u6838\u7f13\u51b2\u533a<br \/>\n3. CPU\u62f7\u8d1d\u6570\u636e\u4ece\u5185\u6838\u7f13\u51b2\u533a\u5230\u7528\u6237\u7f13\u51b2\u533a<br \/>\n4. \u4ece\u5185\u6838\u6001\u8f6c\u5316\u5230\u7528\u6237\u6001<br \/>\n\u56e0\u6b64\u53ef\u89c1\u4f20\u7edf\u6a21\u5f0f\u4e0b\uff0c\u6d89\u53ca\u591a\u6b21\u7a7a\u95f4\u5207\u6362\u548c\u6570\u636e\u5197\u4f59\u62f7\u8d1d\uff0c\u6548\u7387\u5e76\u4e0d\u9ad8\uff0c\u63a5\u4e0b\u6765\u5c31\u8be5\u96f6\u62f7\u8d1d\u6280\u672f\u51fa\u573a\u4e86\u3002<\/p>\n<ul>\n<li>\u96f6\u62f7\u8d1d\u6280\u672f<\/li>\n<\/ul>\n<p>\u964d\u4f4e\u5197\u4f59\u6570\u636e\u62f7\u8d1d\u3001\u89e3\u653eCPU\uff0c\u8fd9\u4e5f\u5c31\u662f\u96f6\u62f7\u8d1dZero-Copy\u6280\u672f\uff1b<br \/>\n\u96f6\u62f7\u8d1d\u6280\u672f\u7684\u51e0\u4e2a\u5b9e\u73b0\u624b\u6bb5\u5305\u62ec\uff1ammap+write\u3001sendfile\u3001sendfile+DMA\u6536\u96c6\u3001splice\u7b49\u3002\u4e0a\u9762\u5c31\u662f\u5176\u4e2d\u4e4b\u4e00\u7684\u6280\u672f<\/p>\n<blockquote><p>\n  kafka\u5728\u4f20\u8f93\u6570\u636e\u4e2d\u96be\u514d\u78b0\u5230\u6570\u636e\u79ef\u538b\u95ee\u9898\uff0c\u4f60\u662f\u600e\u4e48\u5224\u65ad\u7684\uff0c\u4f60\u662f\u600e\u4e48\u89e3\u51b3\u7684\n<\/p><\/blockquote>\n<ul>\n<li>\u51fa\u73b0\u7684\u60c5\u51b5<\/li>\n<\/ul>\n<pre><code class=\"language-java line-numbers\">Auto offset commit failed for group 0: Commit cannot be completed since the group has already rebalanced and assigned the partitions to another member. \nThis means that the time between subsequent calls to poll() was longer than the configured session.timeout.ms, which typically implies that the poll loop is spending too much time message processing. \nYou can address this either by increasing the session timeout or by reducing the maximum size of batches returned in poll() with max.poll.records.\n<\/code><\/pre>\n<p>\u5927\u6982\u7684\u610f\u601d\u662f\u6d88\u8d39\u8005\u7684\u6d88\u8d39\u901f\u5ea6\u5c0f\u4e8e\u751f\u4ea7\u8005\u7684\u4ea7\u751f\u901f\u5ea6,\u6240\u4ee5\u5bfc\u81f4\u4e86\u6d88\u606f\u5806\u79ef,\u4f46\u662f\u901a\u8fc7\u4e4b\u524d\u7684\u6d4b\u8bd5\u53ef\u4ee5\u77e5\u9053.\u6d88\u8d39\u8005\u7684\u901f\u5ea6\u5176\u5b9e\u662f\u8fdc\u5927\u4e8e\u751f\u4ea7\u8005\u7684. \u90a3\u4e48\u662f\u4ec0\u4e48\u539f\u56e0\u5462? \u771f\u76f8\u53ea\u6709\u4e00\u4e2a:\u91cd\u590d\u6d88\u8d39!<\/p>\n<pre><code class=\"language-java line-numbers\">\u4e00\u4e2a\u662f\u589e\u52a0session.timeout.ms\u7684\u65f6\u95f4,\n\n\u4e00\u4e2a\u662f\u8bbe\u7f6e\u4e0d\u8981\u81ea\u52a8\u63d0\u4ea4(enable.auto.commit=false).\n<\/code><\/pre>\n<blockquote><p>\n  \u5982\u679ckafka\u4e2d\u7684\u67d0\u53f0\u673a\u5668\u6302\u6389\uff0c\u4e0b\u6b21\u5982\u679c\u6d88\u8d39\u7684\u4e0d\u662f\u540c\u6837\u7684\u6570\u636e\u600e\u4e48\u529e\n<\/p><\/blockquote>\n<pre><code class=\"language-java line-numbers\">The default partitioning strategy:\n\nIf a partition is specified in the record, use it\nIf no partition is specified but a key is present choose a partition based on a hash of the key\nIf no partition or key is present choose a partition in a round-robin fashion\n<\/code><\/pre>\n<p>\u9ed8\u8ba4\u7684\u5206\u533a\u7b56\u7565\u662f\uff1a<\/p>\n<p>\u5982\u679c\u5728\u53d1\u6d88\u606f\u7684\u65f6\u5019\u6307\u5b9a\u4e86\u5206\u533a\uff0c\u5219\u6d88\u606f\u6295\u9012\u5230\u6307\u5b9a\u7684\u5206\u533a<br \/>\n\u5982\u679c\u6ca1\u6709\u6307\u5b9a\u5206\u533a\uff0c\u4f46\u662f\u6d88\u606f\u7684key\u4e0d\u4e3a\u7a7a\uff0c\u5219\u57fa\u4e8ekey\u7684\u54c8\u5e0c\u503c\u6765\u9009\u62e9\u4e00\u4e2a\u5206\u533a<br \/>\n\u5982\u679c\u65e2\u6ca1\u6709\u6307\u5b9a\u5206\u533a\uff0c\u4e14\u6d88\u606f\u7684key\u4e5f\u662f\u7a7a\uff0c\u5219\u7528\u8f6e\u8be2\u7684\u65b9\u5f0f\u9009\u62e9\u4e00\u4e2a\u5206\u533a<\/p>\n<ol>\n<li>range\u7b56\u7565\u5bf9\u5e94\u7684\u5b9e\u73b0\u7c7b\u662forg.apache.kafka.clients.consumer.RangeAssignor<br \/>\n\u53ef\u4ee5\u901a\u8fc7\u6d88\u8d39\u8005\u914d\u7f6e\u4e2dpartition.assignment.strategy\u53c2\u6570\u6765\u6307\u5b9a\u5206\u914d\u7b56\u7565\uff0c\u5b83\u7684\u503c\u662f\u7c7b\u7684\u5168\u8def\u5f84\uff0c\u662f\u4e00\u4e2a\u6570\u7ec4<\/li>\n<\/ol>\n<ul>\n<li>range\u5206\u914d\u7b56\u7565\u9488\u5bf9\u7684\u662f\u4e3b\u9898\uff08PS\uff1a\u4e5f\u5c31\u662f\u8bf4\uff0c\u8fd9\u91cc\u6240\u8bf4\u7684\u5206\u533a\u6307\u7684\u67d0\u4e2a\u4e3b\u9898\u7684\u5206\u533a\uff0c\u6d88\u8d39\u8005\u503c\u7684\u662f\u8ba2\u9605\u8fd9\u4e2a\u4e3b\u9898\u7684\u6d88\u8d39\u8005\u7ec4\u4e2d\u7684\u6d88\u8d39\u8005\u5b9e\u4f8b\uff09<\/p>\n<\/li>\n<li>\n<p>\u9996\u5148\uff0c\u5c06\u5206\u533a\u6309\u6570\u5b57\u987a\u5e8f\u6392\u884c\u5e8f\uff0c\u6d88\u8d39\u8005\u6309\u6d88\u8d39\u8005\u540d\u79f0\u7684\u5b57\u5178\u5e8f\u6392\u597d\u5e8f<\/p>\n<\/li>\n<li>\n<p>\u7136\u540e\uff0c\u7528\u5206\u533a\u603b\u6570\u9664\u4ee5\u6d88\u8d39\u8005\u603b\u6570\u3002\u5982\u679c\u80fd\u591f\u9664\u5c3d\uff0c\u5219\u7686\u5927\u6b22\u559c\uff0c\u5e73\u5747\u5206\u914d\uff1b\u82e5\u9664\u4e0d\u5c3d\uff0c\u5219\u4f4d\u4e8e\u6392\u5e8f\u524d\u9762\u7684\u6d88\u8d39\u8005\u5c06\u591a\u8d1f\u8d23\u4e00\u4e2a\u5206\u533a<\/p>\n<\/li>\n<\/ul>\n<ol start=\"2\">\n<li>roundrobin\uff08\u8f6e\u8be2\uff09roundronbin\u5206\u914d\u7b56\u7565\u7684\u5177\u4f53\u5b9e\u73b0org.apache.kafka.clients.consumer.RoundRobinAssignor<\/li>\n<\/ol>\n<pre><code class=\"language-java line-numbers\">\u8f6e\u8be2\u5206\u914d\u7b56\u7565\u662f\u57fa\u4e8e\u6240\u6709\u53ef\u7528\u7684\u6d88\u8d39\u8005\u548c\u6240\u6709\u53ef\u7528\u7684\u5206\u533a\u7684\n\n\u4e0e\u524d\u9762\u7684range\u7b56\u7565\u6700\u5927\u7684\u4e0d\u540c\u5c31\u662f\u5b83\u4e0d\u518d\u5c40\u9650\u4e8e\u67d0\u4e2a\u4e3b\u9898\n\n\u5982\u679c\u6240\u6709\u7684\u6d88\u8d39\u8005\u5b9e\u4f8b\u7684\u8ba2\u9605\u90fd\u662f\u76f8\u540c\u7684\uff0c\u90a3\u4e48\u8fd9\u6837\u6700\u597d\u4e86\uff0c\u53ef\u7528\u7edf\u4e00\u5206\u914d\uff0c\u5747\u8861\u5206\u914d\n\n\u4f8b\u5982\uff0c\u5047\u8bbe\u6709\u4e24\u4e2a\u6d88\u8d39\u8005C0\u548cC1\uff0c\u4e24\u4e2a\u4e3b\u9898t0\u548ct1\uff0c\u6bcf\u4e2a\u4e3b\u9898\u67093\u4e2a\u5206\u533a\uff0c\u5206\u522b\u662ft0p0\uff0ct0p1\uff0ct0p2\uff0ct1p0\uff0ct1p1\uff0ct1p2\n\n\u90a3\u4e48\uff0c\u6700\u7ec8\u5206\u914d\u7684\u7ed3\u679c\u662f\u8fd9\u6837\u7684\uff1a\n\nC0: [t0p0, t0p2, t1p1]\n\nC1: [t0p1, t1p0, t1p2]\n<\/code><\/pre>\n<blockquote>\n<p>flume\u4f20\u8f93\u4e2d\u65ad\uff0c\u600e\u4e48\u4fdd\u8bc1\u4e0b\u6b21\u7ee7\u7eed\u4ece\u65ad\u5f00\u7684\u4f4d\u7f6e\u4f20\u8f93<br \/>\n  1. Flume\u57fa\u672c\u7ec4\u4ef6\n<\/p><\/blockquote>\n<p><strong>Event<\/strong>\uff1a\u6570\u636e\u6d88\u606f\u7684\u57fa\u672c\u5355\u4f4d\uff0c\u6709header\uff08\u952e\u503c\u5bf9\uff09\u548cbody\uff08\u5b57\u8282\u6570\u7ec4\uff09\u7ec4\u6210\u3002<\/p>\n<p><strong>Agent<\/strong>\uff1aFlume \u8fd0\u884c\u7684\u6838\u5fc3\u662f Agent\u3002Flume\u4ee5agent\u4e3a\u6700\u5c0f\u7684\u72ec\u7acb\u8fd0\u884c\u5355\u4f4d\u3002\u4e00\u4e2aagent\u5c31\u662f\u4e00\u4e2aJVM\u3002\u5b83\u662f\u4e00\u4e2a\u5b8c\u6574\u7684\u6570\u636e\u6536\u96c6\u5de5\u5177\uff0c\u542b\u6709\u4e09\u4e2a\u6838\u5fc3\u7ec4\u4ef6\uff0c\u5206\u522b\u662fsource\u3001 channel\u3001 sink\u3002\u901a\u8fc7\u8fd9\u4e9b\u7ec4\u4ef6\uff0c Event \u53ef\u4ee5\u4ece\u4e00\u4e2a\u5730\u65b9\u6d41\u5411\u53e6\u4e00\u4e2a\u5730\u65b9<\/p>\n<pre><code class=\"language-java line-numbers\">lume 1.7.0 \u63a8\u51fa\u4e86 taildirSource \u7ec4\u4ef6\u3002tail \u76d1\u63a7 \u76ee\u5f55\u4e0b\u5339\u914d\u4e0a\u6b63\u5219\u8868\u8fbe\u5f0f\u7684 \u7684\u6240\u6709\u6587\u4ef6\uff0c\u5b9e\u73b0\u65ad\u70b9\u7eed\u4f20\u3002\n<\/code><\/pre>\n<blockquote><p>\n  hive\u4e2d\u4f1a\u5bfc\u81f4\u6570\u636e\u503e\u659c\u7684\u7b97\u5b50\u662f\u5565\n<\/p><\/blockquote>\n<ol>\n<li>group by,\u6211\u4f7f\u7528Hive\u5bf9\u6570\u636e\u505a\u4e00\u4e9b\u7c7b\u578b\u7edf\u8ba1\u7684\u65f6\u5019\u9047\u5230\u8fc7\u67d0\u79cd\u7c7b\u578b\u7684\u6570\u636e\u91cf\u7279\u522b\u591a\uff0c\u800c\u5176\u4ed6\u7c7b\u578b\u6570\u636e\u7684\u6570\u636e\u91cf\u7279\u522b\u5c11\u3002\u5f53\u6309\u7167\u7c7b\u578b\u8fdb\u884cgroup by\u7684\u65f6\u5019\uff0c\u4f1a\u5c06\u76f8\u540c\u7684group by\u5b57\u6bb5\u7684reduce\u4efb\u52a1\u9700\u8981\u7684\u6570\u636e\u62c9\u53d6\u5230\u540c\u4e00\u4e2a\u8282\u70b9\u8fdb\u884c\u805a\u5408\uff0c\u800c\u5f53\u5176\u4e2d\u6bcf\u4e00\u7ec4\u7684\u6570\u636e\u91cf\u8fc7\u5927\u65f6\uff0c\u4f1a\u51fa\u73b0\u5176\u4ed6\u7ec4\u7684\u8ba1\u7b97\u5df2\u7ecf\u5b8c\u6210\u800c\u8fd9\u91cc\u8fd8\u6ca1\u8ba1\u7b97\u5b8c\u6210\uff0c\u5176\u4ed6\u8282\u70b9\u7684\u4e00\u76f4\u7b49\u5f85\u8fd9\u4e2a\u8282\u70b9\u7684\u4efb\u52a1\u6267\u884c\u5b8c\u6210\uff0c\u6240\u4ee5\u4f1a\u770b\u5230\u4e00\u76f4map 100%  reduce 99%\u7684\u60c5\u51b5\u3002<\/li>\n<\/ol>\n<pre><code class=\"language-java line-numbers\">\u89e3\u51b3\u65b9\u6cd5\uff1aset hive.map.aggr=true\n\nset hive.groupby.skewindata=true\n\n\u539f\u7406\uff1ahive.map.aggr=true \u8fd9\u4e2a\u914d\u7f6e\u9879\u4ee3\u8868\u662f\u5426\u5728map\u7aef\u8fdb\u884c\u805a\u5408\n<\/code><\/pre>\n<ol start=\"2\">\n<li>\u5f53HiveQL\u4e2d\u5305\u542bcount\uff08distinct\uff09\u65f6\u5982\u679c\u6570\u636e\u91cf\u975e\u5e38\u5927\uff0c\u6267\u884c\u5982select a,count(distinct b) from t group by a;\u7c7b\u578b\u7684SQL\u65f6\uff0c\u4f1a\u51fa\u73b0\u6570\u636e\u503e\u659c\u7684\u95ee\u9898\u3002<\/li>\n<\/ol>\n<pre><code class=\"language-sql line-numbers\">\u89e3\u51b3\u65b9\u6cd5\uff1a\u4f7f\u7528sum...group by\u4ee3\u66ff\u3002\n\u5982select a,sum(1) from (select a, b from t group by a,b) group by a;\n<\/code><\/pre>\n<ol start=\"3\">\n<li>map\u548creduce\u4f18\u5316<\/li>\n<\/ol>\n<pre><code class=\"language-java line-numbers\">1.\u5f53\u51fa\u73b0\u5c0f\u6587\u4ef6\u8fc7\u591a\uff0c\u9700\u8981\u5408\u5e76\u5c0f\u6587\u4ef6\u3002\u53ef\u4ee5\u901a\u8fc7set hive.merge.mapfiles=true\u6765\u89e3\u51b3\u3002\n\n2.\u5355\u4e2a\u6587\u4ef6\u5927\u5c0f\u7a0d\u7a0d\u5927\u4e8e\u914d\u7f6e\u7684block\u5757\u7684\u5927\u5199\uff0c\u6b64\u65f6\u9700\u8981\u9002\u5f53\u589e\u52a0map\u7684\u4e2a\u6570\u3002\u89e3\u51b3\u65b9\u6cd5\uff1aset mapred.map.tasks\u4e2a\u6570\n\n3.\u6587\u4ef6\u5927\u5c0f\u9002\u4e2d\uff0c\u4f46map\u7aef\u8ba1\u7b97\u91cf\u975e\u5e38\u5927\uff0c\u5982select id,count(*),sum(case when...),sum(case when...)...\u9700\u8981\u589e\u52a0map\u4e2a\u6570\u3002\u89e3\u51b3\u65b9\u6cd5\uff1aset mapred.map.tasks\u4e2a\u6570\uff0cset mapred.reduce.tasks\u4e2a\u6570\n<\/code><\/pre>\n<blockquote><p>\n  map\u7aef\u80fd\u5bfc\u81f4\u6570\u636e\u503e\u659c\u5417\uff0c\u5982\u679c\u80fd\u7684\u8bdd\u54ea\u79cd\u60c5\u51b5\u80fd\u5bfc\u81f4\u6570\u636e\u503e\u659c<\/p>\n<p>  \u540c\u4e00\u4e2a\u6d88\u8d39\u8005\u7ec4\u7684\u4e0d\u540c\u7ebf\u7a0b\u80fd\u6d88\u8d39\u540c\u4e00\u4e2a\u6570\u636e\u5417\uff0c\u4e0d\u80fd\u7684\u8bdd\u600e\u4e48\u505a\n<\/p><\/blockquote>\n<p><code>\u6d88\u8d39\u8005\u7ec4\u662f<\/code>Kafka\u5b9e\u73b0\u5355\u64ad\u548c\u5e7f\u64ad\u4e24\u79cd\u6d88\u606f\u6a21\u578b\u7684\u624b\u6bb5\u3002\u540c\u4e00\u4e2atopic\uff0c\u6bcf\u4e2a\u6d88\u8d39\u8005\u7ec4\u90fd\u53ef\u4ee5\u62ff\u5230\u76f8\u540c\u7684\u5168\u90e8\u6570\u636e\u3002<br \/>\n\u540c\u4e00\u4e2a\u6d88\u8d39\u8005\u7ec4\u7684\u6d88\u8d39\u8005\u4e0d\u80fd\u6d88\u8d39\u540c\u4e00\u4e2a\u6570\u636e\uff0c\u53ef\u4ee5\u5c06\u8fd9\u4e2a\u6d88\u8d39\u8005\u653e\u5230\u4e0d\u540c\u7684\u6d88\u8d39\u8005\u7ec4\u90a3\u4e48\u5c31\u53ef\u4ee5\u6d88\u8d39\u8fd9\u4e2a\u6d88\u606f,\u76f8\u540c\u7684\u6570\u636e\u4f1a\u88ab\u4e0d\u540c\u7ec4\u7684\u6d88\u8d39\u8005\u6d88\u8d39\u591a\u6b21;<\/p>\n<blockquote><p>\n  MySQL\u4e2d\u7684\u7d22\u5f15\u7c7b\u578b\u6709\u54ea\u4e9b<br \/>\n  Mysql\u76ee\u524d\u4e3b\u8981\u6709\u4ee5\u4e0b\u51e0\u79cd\u7d22\u5f15\u7c7b\u578b\uff1aFULLTEXT\uff0cHASH\uff0cBTREE\uff0cRTREE\u3002\n<\/p><\/blockquote>\n<ol>\n<li>FULLTEXT<br \/>\n\u5373\u4e3a\u5168\u6587\u7d22\u5f15\uff0c\u76ee\u524d\u53ea\u6709MyISAM\u5f15\u64ce\u652f\u6301\u3002\u5176\u53ef\u4ee5\u5728CREATE TABLE \uff0cALTER TABLE \uff0cCREATE INDEX \u4f7f\u7528\uff0c\u4e0d\u8fc7\u76ee\u524d\u53ea\u6709 CHAR\u3001VARCHAR \uff0cTEXT \u5217\u4e0a\u53ef\u4ee5\u521b\u5efa\u5168\u6587\u7d22\u5f15\u3002<\/li>\n<\/ol>\n<p>\u5168\u6587\u7d22\u5f15\u5e76\u4e0d\u662f\u548cMyISAM\u4e00\u8d77\u8bde\u751f\u7684\uff0c\u5b83\u7684\u51fa\u73b0\u662f\u4e3a\u4e86\u89e3\u51b3WHERE name LIKE \u201c%word%&#8221;\u8fd9\u7c7b\u9488\u5bf9\u6587\u672c\u7684\u6a21\u7cca\u67e5\u8be2\u6548\u7387\u8f83\u4f4e\u7684\u95ee\u9898\u3002<\/p>\n<ol start=\"2\">\n<li>HASH<br \/>\n\u7531\u4e8eHASH\u7684\u552f\u4e00\uff08\u51e0\u4e4e100%\u7684\u552f\u4e00\uff09\u53ca\u7c7b\u4f3c\u952e\u503c\u5bf9\u7684\u5f62\u5f0f\uff0c\u5f88\u9002\u5408\u4f5c\u4e3a\u7d22\u5f15\u3002<\/li>\n<\/ol>\n<p>HASH\u7d22\u5f15\u53ef\u4ee5\u4e00\u6b21\u5b9a\u4f4d\uff0c\u4e0d\u9700\u8981\u50cf\u6811\u5f62\u7d22\u5f15\u90a3\u6837\u9010\u5c42\u67e5\u627e,\u56e0\u6b64\u5177\u6709\u6781\u9ad8\u7684\u6548\u7387\u3002\u4f46\u662f\uff0c\u8fd9\u79cd\u9ad8\u6548\u662f\u6709\u6761\u4ef6\u7684\uff0c\u5373\u53ea\u5728\u201c=\u201d\u548c\u201cin\u201d\u6761\u4ef6\u4e0b\u9ad8\u6548\uff0c\u5bf9\u4e8e\u8303\u56f4\u67e5\u8be2\u3001\u6392\u5e8f\u53ca\u7ec4\u5408\u7d22\u5f15\u4ecd\u7136\u6548\u7387\u4e0d\u9ad8\u3002<\/p>\n<ol start=\"3\">\n<li>BTREE<br \/>\nBTREE\u7d22\u5f15\u5c31\u662f\u4e00\u79cd\u5c06\u7d22\u5f15\u503c\u6309\u4e00\u5b9a\u7684\u7b97\u6cd5\uff0c\u5b58\u5165\u4e00\u4e2a\u6811\u5f62\u7684\u6570\u636e\u7ed3\u6784\u4e2d\uff08\u4e8c\u53c9\u6811\uff09\uff0c\u6bcf\u6b21\u67e5\u8be2\u90fd\u662f\u4ece\u6811\u7684\u5165\u53e3root\u5f00\u59cb\uff0c\u4f9d\u6b21\u904d\u5386node\uff0c\u83b7\u53d6leaf\u3002\u8fd9\u662fMySQL\u91cc\u9ed8\u8ba4\u548c\u6700\u5e38\u7528\u7684\u7d22\u5f15\u7c7b\u578b\u3002<\/p>\n<\/li>\n<li>\n<p>RTREE<br \/>\nRTREE\u5728MySQL\u5f88\u5c11\u4f7f\u7528\uff0c\u4ec5\u652f\u6301geometry\u6570\u636e\u7c7b\u578b\uff0c\u652f\u6301\u8be5\u7c7b\u578b\u7684\u5b58\u50a8\u5f15\u64ce\u53ea\u6709MyISAM\u3001BDb\u3001InnoDb\u3001NDb\u3001Archive\u51e0\u79cd\u3002<\/p>\n<\/li>\n<\/ol>\n<p>\u76f8\u5bf9\u4e8eBTREE\uff0cRTREE\u7684\u4f18\u52bf\u5728\u4e8e\u8303\u56f4\u67e5\u627e\u3002<\/p>\n<p>ps. \u6b64\u6bb5\u8be6\u7ec6\u5185\u5bb9\u89c1\u6b64\u7247\u535a\u6587\uff1aMysql\u51e0\u79cd\u7d22\u5f15\u7c7b\u578b\u7684\u533a\u522b\u53ca\u9002\u7528\u60c5\u51b5<\/p>\n<blockquote><p>\n  \u7d22\u5f15\u79cd\u7c7b\n<\/p><\/blockquote>\n<p>\u7d22\u5f15\u662f\u5bf9\u6570\u636e\u5e93\u8868\u4e2d\u4e00\u5217\u6216\u591a\u5217\u7684\u503c\u8fdb\u884c\u6392\u5e8f\u7684\u4e00\u79cd\u7ed3\u6784\uff0c\u4f7f\u7528\u7d22\u5f15\u53ef\u5feb\u901f\u8bbf\u95ee\u6570\u636e\u5e93\u8868\u4e2d\u7684\u7279\u5b9a\u4fe1\u606f\u3002\u4f8b\u5982\u8fd9\u6837\u4e00\u4e2a\u67e5\u8be2\uff1aselect * from table1 where id=44\u3002\u5982\u679c\u6ca1\u6709\u7d22\u5f15\uff0c\u5fc5\u987b\u904d\u5386\u6574\u4e2a\u8868\uff0c\u76f4\u5230ID\u7b49\u4e8e44\u7684\u8fd9\u4e00\u884c\u88ab\u627e\u5230\u4e3a\u6b62\uff1b\u6709\u4e86\u7d22\u5f15\u4e4b\u540e(\u5fc5\u987b\u662f\u5728ID\u8fd9\u4e00\u5217\u4e0a\u5efa\u7acb\u7684\u7d22\u5f15)\uff0c\u76f4\u63a5\u5728\u7d22\u5f15\u91cc\u9762\u627e44\uff08\u4e5f\u5c31\u662f\u5728ID\u8fd9\u4e00\u5217\u627e\uff09<\/p>\n<ul>\n<li>\u666e\u901a\u7d22\u5f15\uff1a\u4ec5\u52a0\u901f\u67e5\u8be2<\/p>\n<\/li>\n<li>\n<p>\u552f\u4e00\u7d22\u5f15\uff1a\u52a0\u901f\u67e5\u8be2 + \u5217\u503c\u552f\u4e00\uff08\u53ef\u4ee5\u6709null\uff09<\/p>\n<\/li>\n<li>\n<p>\u4e3b\u952e\u7d22\u5f15\uff1a\u52a0\u901f\u67e5\u8be2 + \u5217\u503c\u552f\u4e00\uff08\u4e0d\u53ef\u4ee5\u6709null\uff09+ \u8868\u4e2d\u53ea\u6709\u4e00\u4e2a<\/p>\n<\/li>\n<li>\n<p>\u7ec4\u5408\u7d22\u5f15\uff1a\u591a\u5217\u503c\u7ec4\u6210\u4e00\u4e2a\u7d22\u5f15\uff0c\u4e13\u95e8\u7528\u4e8e\u7ec4\u5408\u641c\u7d22\uff0c\u5176\u6548\u7387\u5927\u4e8e\u7d22\u5f15\u5408\u5e76<\/p>\n<\/li>\n<li>\n<p>\u5168\u6587\u7d22\u5f15\uff1a\u5bf9\u6587\u672c\u7684\u5185\u5bb9\u8fdb\u884c\u5206\u8bcd\uff0c\u8fdb\u884c\u641c\u7d22<\/p>\n<\/li>\n<\/ul>\n<blockquote>\n<p>Linux\u600e\u4e48\u67e5\u770b\u5360\u7528CPU\u524d10\u7684\u8fdb\u7a0b\n<\/p><\/blockquote>\n<ul>\n<li>\u627e\u51fa\u5360\u7528\u5185\u5b58\u8d44\u6e90\u6700\u591a\u7684\u524d 10 \u4e2a\u8fdb\u7a0b<br \/>\n<code>ps -auxf | sort -nr -k 4 | head -10<\/code><\/li>\n<\/ul>\n<pre><code class=\"language-bash line-numbers\">[root@wq1 ~]# ps -auxf | sort -nr -k 4 | head -10\ngdm        1613  0.2  9.1 3565508 138728 ?      Sl   00:45   1:56          \\_ \/usr\/bin\/gnome-shell\nroot       1202  0.0  1.6 314424 25392 tty1     Ssl+ 00:45   0:10  \\_ \/usr\/bin\/X :0 -background none -noreset -audit 4 -verbose -auth \/run\/gdm\/auth-for-gdm-QNHBVw\/database -seat seat0 -nolisten tcp vt1\nroot       1124  0.0  1.2 574304 19524 ?        Ssl  00:44   0:14 \/usr\/bin\/python2 -Es \/usr\/sbin\/tuned -l -P\ngdm        1755  0.0  1.1 632032 16900 ?        Sl   00:46   0:01          \\_ \/usr\/libexec\/gsd-power\ngdm        1741  0.0  1.1 1012404 17796 ?       Sl   00:46   0:00          \\_ \/usr\/libexec\/gsd-media-keys\ngdm        1721  0.0  1.1 714352 16640 ?        Sl   00:46   0:10          \\_ \/usr\/libexec\/gsd-color\nroot       1131  0.0  1.0 1004992 16120 ?       Ssl  00:44   0:08 \/usr\/sbin\/libvirtd\ngdm        1720  0.0  1.0 464796 15584 ?        Sl   00:46   0:00          \\_ \/usr\/libexec\/gsd-clipboard\ngdm        1682  0.0  1.0 465112 15812 ?        Sl   00:46   0:00 \/usr\/libexec\/ibus-x11 --kill-daemon\ngdm        1780  0.0  0.9 549632 14300 ?        Sl   00:46   0:00          \\_ \/usr\/libexec\/gsd-wacom\n<\/code><\/pre>\n<ul>\n<li>\u627e\u51fa\u5360\u7528 CPU \u8d44\u6e90\u6700\u591a\u7684\u524d 10 \u4e2a\u8fdb\u7a0b <code>ps -auxf | sort -nr -k 3 | head -10<\/code><\/li>\n<\/ul>\n<pre><code class=\"language-bash line-numbers\">[root@wq1 ~]# ps -auxf | sort -nr -k 3 | head -10\nroot        744  0.2  0.4 324784  7028 ?        Ssl  00:44   2:16 \/usr\/bin\/vmtoolsd\ngdm        1613  0.2  9.1 3565508 138728 ?      Sl   00:45   1:56          \\_ \/usr\/bin\/gnome-shell\nroot      10957  0.1  0.4 350508  6780 ?        Sl   14:11   0:00 \/usr\/sbin\/abrt-dbus -t133\nroot      10931  0.1  0.4 163620  6132 ?        Ss   14:11   0:00  \\_ sshd: root@pts\/0\nroot      10701  0.1  0.0      0     0 ?        S    13:50   0:01  \\_ [kworker\/0:1]\nUSER        PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND\nrtkit       734  0.0  0.1 198808  1796 ?        SNsl 00:44   0:04 \/usr\/libexec\/rtkit-daemon\nrpc         732  0.0  0.0  69280  1008 ?        Ss   00:44   0:00 \/sbin\/rpcbind -w\nroot       9978  0.0  0.0      0     0 ?        S    12:53   0:00  \\_ [kworker\/3:0]\nroot          9  0.0  0.0      0     0 ?        S    00:44   0:20  \\_ [rcu_sched]\n<\/code><\/pre>\n<blockquote><p>\n  Linux\u4e0a\u5185\u5b58\u7684buff\u548ccache\u90fd\u662f\u4ec0\u4e48\u542b\u4e49\n<\/p><\/blockquote>\n<p>\u8fd9\u662fLinux\u4e00\u79cd\u975e\u5e38\u4f18\u79c0\u7684\u8bbe\u8ba1\uff0c\u76ee\u7684\u5c31\u662f\u4e3a\u4e86\u63d0\u5347\u78c1\u76d8IO\u7684\u6027\u80fd\uff0c\u4ece\u4f4e\u901f\u7684\u5757\u8bbe\u5907\u4e0a\u8bfb\u53d6\u7684\u6570\u636e\u4f1a\u6682\u65f6\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u5373\u4f7f\u6570\u636e\u5728\u5f53\u65f6\u5df2\u7ecf\u4e0d\u518d\u9700\u8981\u4e86\uff0c\u4f46\u5728\u5e94\u7528\u7a0b\u5e8f\u4e0b\u4e00\u6b21\u8bbf\u95ee\u8be5\u6570\u636e\u65f6\uff0c\u5b83\u53ef\u4ee5\u4ece\u5185\u5b58\u4e2d\u76f4\u63a5\u8bfb\u53d6\uff0c\u7ed5\u5f00\u4e86\u4f4e\u901f\u7684\u5757\u8bbe\u5907\uff0c\u4ece\u800c\u63d0\u9ad8\u7cfb\u7edf\u7684\u6574\u4f53\u6027\u80fd\u3002<br \/>\n\u4e3a\u4e86\u63d0\u9ad8\u7cfb\u7edf\u6027\u80fd\u548c\u4e0d\u6d6a\u8d39\u5185\u5b58\uff0clinux\u628a\u591a\u7684\u5185\u5b58\u505a\u4e86cache\uff0c\u4ee5\u63d0\u9ad8io\u901f\u5ea6.\u4f60\u7684\u90a3\u4e9b\u5185\u5b58\u5e76\u6ca1\u6709\u88ab\u5360\u7528\u3002\u5bf9\u4e8e\u5185\u6838\u6765\u8bf4\uff0cbuffer \u548c cache \u5176\u5b9e\u90fd\u5c5e\u4e8e\u5df2\u7ecf\u88ab\u4f7f\u7528\u7684\u5185\u5b58\u3002\u4f46\u5f53\u5e94\u7528\u7a0b\u5e8f\u7533\u8bf7\u5185\u5b58\u65f6\uff0c\u5982\u679c free \u5185\u5b58\u4e0d\u591f\uff0c\u5185\u6838\u5c31\u4f1a\u56de\u6536 buffer \u548c cache \u7684\u5185\u5b58\u6765\u6ee1\u8db3\u5e94\u7528\u7a0b\u5e8f\u7684\u8bf7\u6c42<br \/>\n<code>buff<\/code>:\u5373\u5199\u5982\u78c1\u76d8\u65f6\uff0c\u5148\u4fdd\u5b58\u5230\u78c1\u76d8\u7f13\u51b2\u533a(buffer)\uff0c\u7136\u540e\u518d\u5199\u5165\u5230\u78c1\u76d8\u3002<br \/>\n<code>cache<\/code>:\u5373\u8bfb\u78c1\u76d8\u65f6\uff0c\u6570\u636e\u4ece\u78c1\u76d8\u8bfb\u51fa\u540e\uff0c\u6682\u7559\u5728\u7f13\u51b2\u533a(cache)\uff0c\u4e3a\u540e\u7eed\u7a0b\u5e8f\u7684\u4f7f\u7528\u505a\u51c6\u5907\u3002<\/p>\n<blockquote><p>\n  df -lh \u4e0efree -lh\u4e2dlh\u7684\u542b\u4e49\u662f\u4ec0\u4e48\n<\/p><\/blockquote>\n<pre><code class=\"language-bash line-numbers\">[root@wq1 ~]# df --help\n  -a, --all             include pseudo, duplicate, inaccessible file systems\n  -B, --block-size=SIZE  scale sizes by SIZE before printing them; e.g.,\n                           '-BM' prints sizes in units of 1,048,576 bytes;\n                           see SIZE format below\n      --direct          show statistics for a file instead of mount point\n      --total           produce a grand total\n  -h, --human-readable  print sizes in human readable format (e.g., 1K 234M 2G)\n  -H, --si              likewise, but use powers of 1000 not 1024\n  -i, --inodes          \u663e\u793ainode \u4fe1\u606f\u800c\u975e\u5757\u4f7f\u7528\u91cf\n  -k                    \u5373--block-size=1K\n  -l, --local           \u53ea\u663e\u793a\u672c\u673a\u7684\u6587\u4ef6\u7cfb\u7edf\n      --no-sync         \u53d6\u5f97\u4f7f\u7528\u91cf\u6570\u636e\u524d\u4e0d\u8fdb\u884c\u540c\u6b65\u52a8\u4f5c(\u9ed8\u8ba4)\n      --output[=FIELD_LIST]  use the output format defined by FIELD_LIST,\n                               or print all fields if FIELD_LIST is omitted.\n  -P, --portability     use the POSIX output format\n      --sync            invoke sync before getting usage info\n  -t, --type=TYPE       limit listing to file systems of type TYPE\n  -T, --print-type      print file system type\n  -x, --exclude-type=TYPE   limit listing to file systems not of type TYPE\n  -v                    (ignored)\n      --help            \u663e\u793a\u6b64\u5e2e\u52a9\u4fe1\u606f\u5e76\u9000\u51fa\n      --version         \u663e\u793a\u7248\u672c\u4fe1\u606f\u5e76\u9000\u51fa\n<\/code><\/pre>\n<p>free<\/p>\n<pre><code class=\"language-bash line-numbers\">[root@wq1 ~]# free --help\n\nUsage:\n free [options]\n\nOptions:\n -b, --bytes         show output in bytes\n -k, --kilo          show output in kilobytes\n -m, --mega          show output in megabytes\n -g, --giga          show output in gigabytes\n     --tera          show output in terabytes\n     --peta          show output in petabytes\n -h, --human         show human-readable output\n     --si            use powers of 1000 not 1024\n -l, --lohi          show detailed low and high memory statistics\n -t, --total         show total for RAM + swap\n -s N, --seconds N   repeat printing every N seconds\n -c N, --count N     repeat printing N times, then exit\n -w, --wide          wide output\n\n     --help     display this help and exit\n -V, --version  output version information and exit\n<\/code><\/pre>\n<blockquote><p>\n  \u4e3a\u4ec0\u4e48\u88abfinal\u4fee\u9970\u7684\u5e38\u91cf\u4e0d\u80fd\u88ab\u518d\u4fee\u6539<br \/>\n  \u8fd9\u5c31\u7275\u626f\u51fa\u4e00\u4e2a\u95ee\u9898\uff1a\u4f7f\u7528 final \u5173\u952e\u5b57\u4fee\u9970\u4e00\u4e2a\u53d8\u91cf\u65f6\uff0c\u662f\u5f15\u7528\u4e0d\u80fd\u53d8\uff0c\u8fd8\u662f\u5f15\u7528\u7684\u5bf9\u8c61\u4e0d\u80fd\u53d8\uff1f\n<\/p><\/blockquote>\n<pre><code class=\"language-java line-numbers\">\/\/1) \u5bf9\u8c61\u76f8\u7b49\u5219hashCode\u4e00\u5b9a\u76f8\u7b49\uff1b\n\/\/2) hashCode\u76f8\u7b49\u5bf9\u8c61\u672a\u5fc5\u76f8\u7b49\u3002\n  public static void main(String[] args) {\n        final StringBuilder sb = new StringBuilder(\"haha\");;\n        \/\/\u540c\u4e00\u5bf9\u8c61\u7684hashCode\u503c\u76f8\u540c\n        System.out.println(\"sb\u4e2d\u7684\u5185\u5bb9\u662f\uff1a\"+sb);\n        sb.append(\"\u6211\u53d8\u4e86\");\n        System.out.println(\"sb\u4e2d\u7684\u5185\u5bb9\u662f\uff1a\"+sb);\n        System.out.println( sb.append(\"\u6211\u53d8\u4e86\")==sb);\n        System.out.println( sb.append(\"\u6211\u53d8\u4e86\").equals(sb));\n    }\nsb\u4e2d\u7684\u5185\u5bb9\u662f\uff1ahaha\nsb\u4e2d\u7684\u5185\u5bb9\u662f\uff1ahaha\u6211\u53d8\u4e86\ntrue\ntrue\n\n<\/code><\/pre>\n<p><code>\u7ed3\u8bba<\/code>:\u4f7f\u7528final\u5173\u952e\u5b57\u4fee\u9970\u4e00\u4e2a\u53d8\u91cf\u65f6\uff0c\u662f\u6307\u5f15\u7528\u53d8\u91cf\u4e0d\u80fd\u53d8\uff0c\u5f15\u7528\u53d8\u91cf\u6240\u6307\u5411\u7684\u5bf9\u8c61\u4e2d\u7684\u5185\u5bb9\u8fd8\u662f\u53ef\u4ee5\u6539\u53d8\u7684\u3002<\/p>\n<blockquote><p>\n  \u591a\u7ebf\u7a0b\u7684\u5b9e\u73b0\u65b9\u5f0f\n<\/p><\/blockquote>\n<p>\u7ee7\u627fThread\u7c7b\u3001\u5b9e\u73b0Runnable\u63a5\u53e3\u3001\u5b9e\u73b0Callable\u63a5\u53e3\u901a\u8fc7FutureTask\u5305\u88c5\u5668\u6765\u521b\u5efaThread\u7ebf\u7a0b\u3001\u4f7f\u7528ExecutorService\u3001Callable\u3001Future\u5b9e\u73b0\u6709\u8fd4\u56de\u7ed3\u679c\u7684\u591a\u7ebf\u7a0b\u3002<\/p>\n<blockquote><p>\n  ArrayList\u4e0eLinkedList\u7684\u533a\u522b\uff0c\u4ee5\u53ca\u5e94\u7528\u573a\u666f\n<\/p><\/blockquote>\n<p>ArrayList\u662f\u5b9e\u73b0\u4e86\u57fa\u4e8e\u52a8\u6001\u6570\u7ec4\u7684\u6570\u636e\u7ed3\u6784\uff0cLinkedList\u662f\u57fa\u4e8e\u94fe\u8868\u7ed3\u6784\u3002<br \/>\n\u5bf9\u4e8e\u968f\u673a\u8bbf\u95ee\u7684get\u548cset\u65b9\u6cd5\uff0cArrayList\u8981\u4f18\u4e8eLinkedList\uff0c\u56e0\u4e3aLinkedList\u8981\u79fb\u52a8\u6307\u9488\u3002<br \/>\n\u5bf9\u4e8e\u65b0\u589e\u548c\u5220\u9664\u64cd\u4f5cadd\u548cremove\uff0cLinkedList\u6bd4\u8f83\u5360\u4f18\u52bf\uff0c\u56e0\u4e3aArrayList\u8981\u79fb\u52a8\u6570\u636e\u3002<br \/>\nArrayList\u4f7f\u7528\u5728\u67e5\u8be2\u6bd4\u8f83\u591a\uff0c\u4f46\u662f\u63d2\u5165\u548c\u5220\u9664\u6bd4\u8f83\u5c11\u7684\u60c5\u51b5\uff0c\u800cLinkedList\u7528\u5728\u67e5\u8be2\u6bd4\u8f83\u5c11\u800c\u63d2\u5165\u5220\u9664\u6bd4\u8f83\u591a\u7684\u60c5\u51b5<\/p>\n<blockquote><p>\n  String stringbuffer stringbuilder\u4e09\u8005\u4e4b\u95f4\u7684\u533a\u522b\n<\/p><\/blockquote>\n<pre><code class=\"language-java line-numbers\">String\uff1a\u4e0d\u53ef\u53d8\u5b57\u7b26\u4e32\uff1b\n\nStringBuffer\uff1a\u53ef\u53d8\u5b57\u7b26\u4e32\u3001\u6548\u7387\u4f4e\u3001\u7ebf\u7a0b\u5b89\u5168\uff1b\n\nStringBuilder\uff1a\u53ef\u53d8\u5b57\u7b26\u5e8f\u5217\u3001\u6548\u7387\u9ad8\u3001\u7ebf\u7a0b\u4e0d\u5b89\u5168\uff1b\n\u521d\u59cb\u5316\u4e0a\u7684\u533a\u522b\uff0cString\u53ef\u4ee5\u7a7a\u8d4b\u503c\uff0c\u540e\u8005\u4e0d\u884c\uff0c\u62a5\u9519\n<\/code><\/pre>\n<p>\uff081\uff09\u5982\u679c\u8981\u64cd\u4f5c\u5c11\u91cf\u7684\u6570\u636e\u7528 String\uff1b<\/p>\n<p>\uff082\uff09\u591a\u7ebf\u7a0b\u64cd\u4f5c\u5b57\u7b26\u4e32\u7f13\u51b2\u533a\u4e0b\u64cd\u4f5c\u5927\u91cf\u6570\u636e StringBuffer\uff1b<\/p>\n<p>\uff083\uff09\u5355\u7ebf\u7a0b\u64cd\u4f5c\u5b57\u7b26\u4e32\u7f13\u51b2\u533a\u4e0b\u64cd\u4f5c\u5927\u91cf\u6570\u636e StringBuilder\uff08\u63a8\u8350\u4f7f\u7528\uff09\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u4e00\u8bf4\u4f60\u5728\u5de5\u4f5c\u4e2d\u9047\u5230\u4e86\u4ec0\u4e48\u95ee\u9898\uff0c\u4f60\u662f\u600e\u4e48\u5224\u65ad\u8fd9\u4e2a\u95ee\u9898\u7684\uff0c\u4ee5\u53ca\u662f\u600e\u4e48\u89e3\u51b3\u7684\n<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>\u5728\u8fd0\u7528\u5927\u6570\u636e\u6280\u672f\u5904\u7406\u6570\u636e\u8fc7\u7a0b\u4e2d\u6d89\u53ca\u5230\u5982\u4e0b\u51e0\u4e2a\u65b9\u9762\u7684\u95ee\u9898 \u5728\u4f20\u8f93\u6570\u636e\u65f6\u600e\u4e48\u628a\u6570\u636e\u5b8c\u6574\u7684\u62ff\u8fc7\u6765\u662f\u9996\u8981\u89e3\u51b3\u7684\u95ee\u9898 \u8fd9 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":1356,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[7],"tags":[],"_links":{"self":[{"href":"http:\/\/www.specialwu.com\/index.php?rest_route=\/wp\/v2\/posts\/1354"}],"collection":[{"href":"http:\/\/www.specialwu.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.specialwu.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.specialwu.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.specialwu.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1354"}],"version-history":[{"count":13,"href":"http:\/\/www.specialwu.com\/index.php?rest_route=\/wp\/v2\/posts\/1354\/revisions"}],"predecessor-version":[{"id":2143,"href":"http:\/\/www.specialwu.com\/index.php?rest_route=\/wp\/v2\/posts\/1354\/revisions\/2143"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.specialwu.com\/index.php?rest_route=\/wp\/v2\/media\/1356"}],"wp:attachment":[{"href":"http:\/\/www.specialwu.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1354"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.specialwu.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1354"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.specialwu.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1354"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}