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如何选择机器学习算法 - 大数据 & AI - 清泛网移动版 - 专注C/C++及内核技术

...学习算法Choosing-a-Machine-Learning-Classifier如何针对某个分类问题决定使用何种机器学习算法? 当然,如果你真心在乎准确率,最好的途径就是测试一大堆各式各样的算法(同时确保在每个算法上也测试不同的参数),最后选择在交...
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廉价共享存储解决方案2-drbd+cman+gfs2 - 更多技术 - 清泛网 - 专注C/C++及内核技术

...同时读写可能会有IO异常,导致drbd设备失效 为了解决这个问题则使用 gfs + cman 实现分布式文件锁方案 3.3安装cman yum –y cman 3.4 gfs集群文件系统 在 /usr/local/drbd-utils-8.9.4/etc/drbd.conf 在配置文件的 net 选项中 all...
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实现一个简单的服务端推方案 - 更多技术 - 清泛网 - 专注C/C++及内核技术

...时性较差。虽然可以通过加快轮询频率的方式来缓解这个问题,但相应付出的代价也不小:一来会使负载居高不下,二来也会让带宽捉襟见肘。 再来说说Long Polling,如果使用传统的LAMP技术去实现的话,大致如下所示: Long Pol...
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How do I measure time elapsed in Java? [duplicate]

...in milliseconds. It has methods methods like split(), suspend(), resume(), etc that allow to take measure at different points of the execution and that you may find convenient. Have a look at it. System.nanoTime() You may prefer to use System.nanoTime() if you are looking for extremely precise mea...
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微博为什么限制140字(附短信70字限制考) - 创意 - 清泛网 - 专注C/C++及内核技术

微博为什么限制140字(附短信70字限制考)问题的提出申请过那么多的微博,数申请网易微博的动机最不纯,因为它的字数限制不是传说中的140字,而是163个字。当年觉得很可爱,于是就注...问题的提出 申请过那么多的微博,数申...
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Debug Error \"pure virtual function call\" 原因解析 - 更多技术 - 清泛...

...函数中抛出异常,不然,我们不得不面对以下两个严重的问题: 二次异常导致程序退出; 遗留下来的未完全销毁的对象与未完成的工作导致的后续问题 pure virtual function call就是这种情况。 但是理想与现实总是有差距的,...
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Finding Number of Cores in Java

...logical threads actually available to the JVM (at startup I guess). Using CPU affinity the user/OS can restrict the number of "cores" a JVM sees. You can even do it on a running JVM but I'm not too sure how this influence availableProcessors(). – SyntaxT3rr0r ...
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Why does my application spend 24% of its life doing a null check?

...uting instructions, it is accessing memory. The execution core of a modern CPU is many times faster than the memory bus. A problem related to distance, the further an electrical signal has to travel, the harder it gets to get that signal delivered to the other end of the wire without it being corrup...
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What is the advantage of GCC's __builtin_expect in if else statements?

...ase precedes the foo case (as opposed to the C code). This can utilise the CPU pipeline better, since a jump thrashes the already fetched instructions. Before the jump is executed, the instructions below it (the bar case) are pushed to the pipeline. Since the foo case is unlikely, jumping too is un...
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Select random lines from a file

...0 --file lines_78000000000.txt > /dev/null 0.02s user 0.01s system 80% cpu 0.047 total The reason it is so fast, well I don't read the whole file and just move the file pointer 10 times and print the line after the pointer. Gitlab Repo Old attempt First I needed a file of 78.000.000.000 lines:...