erlang

Erlang: ets select and match performance

由 二次信任 提交于 2020-12-31 04:35:02
问题 I find "The functions ets:select/2 and mnesia:select/3 should be preferred over ets:match/2,ets:match_object/2, and mnesia:match_object/3" form ref link : http://www.erlang.org/doc/efficiency_guide/tablesDatabases.html And I'd read some essay about comparing between select and match, I conclude there are some factor effecting the result, such as records' amount in table, select/match a primary key or not, table kind(bag, set...), etc. In my test, I do for all kind of table with 10W records

Erlang: ets select and match performance

由 [亡魂溺海] 提交于 2020-12-31 04:34:13
问题 I find "The functions ets:select/2 and mnesia:select/3 should be preferred over ets:match/2,ets:match_object/2, and mnesia:match_object/3" form ref link : http://www.erlang.org/doc/efficiency_guide/tablesDatabases.html And I'd read some essay about comparing between select and match, I conclude there are some factor effecting the result, such as records' amount in table, select/match a primary key or not, table kind(bag, set...), etc. In my test, I do for all kind of table with 10W records

Erlang: ets select and match performance

由 自闭症网瘾萝莉.ら 提交于 2020-12-31 04:32:37
问题 I find "The functions ets:select/2 and mnesia:select/3 should be preferred over ets:match/2,ets:match_object/2, and mnesia:match_object/3" form ref link : http://www.erlang.org/doc/efficiency_guide/tablesDatabases.html And I'd read some essay about comparing between select and match, I conclude there are some factor effecting the result, such as records' amount in table, select/match a primary key or not, table kind(bag, set...), etc. In my test, I do for all kind of table with 10W records

RabbitMQ installation Error

由 南楼画角 提交于 2020-12-29 07:16:48
问题 I am installing rabbitMQ on ubuntu16.04. But I am getting below error. I tries searching for it but not able to resolve it. Adding group `rabbitmq' (GID 131) ... Done. Adding system user `rabbitmq' (UID 123) ... Adding new user `rabbitmq' (UID 123) with group `rabbitmq' ... Not creating home directory `/var/lib/rabbitmq'. Job for rabbitmq-server.service failed because the control process exited with error code. See "systemctl status rabbitmq-server.service" and "journalctl -xe" for details.

RabbitMQ installation Error

由 喜你入骨 提交于 2020-12-29 07:14:33
问题 I am installing rabbitMQ on ubuntu16.04. But I am getting below error. I tries searching for it but not able to resolve it. Adding group `rabbitmq' (GID 131) ... Done. Adding system user `rabbitmq' (UID 123) ... Adding new user `rabbitmq' (UID 123) with group `rabbitmq' ... Not creating home directory `/var/lib/rabbitmq'. Job for rabbitmq-server.service failed because the control process exited with error code. See "systemctl status rabbitmq-server.service" and "journalctl -xe" for details.

RabbitMQ installation Error

由 笑着哭i 提交于 2020-12-29 07:14:31
问题 I am installing rabbitMQ on ubuntu16.04. But I am getting below error. I tries searching for it but not able to resolve it. Adding group `rabbitmq' (GID 131) ... Done. Adding system user `rabbitmq' (UID 123) ... Adding new user `rabbitmq' (UID 123) with group `rabbitmq' ... Not creating home directory `/var/lib/rabbitmq'. Job for rabbitmq-server.service failed because the control process exited with error code. See "systemctl status rabbitmq-server.service" and "journalctl -xe" for details.

RabbitMQ installation Error

由 泄露秘密 提交于 2020-12-29 07:12:47
问题 I am installing rabbitMQ on ubuntu16.04. But I am getting below error. I tries searching for it but not able to resolve it. Adding group `rabbitmq' (GID 131) ... Done. Adding system user `rabbitmq' (UID 123) ... Adding new user `rabbitmq' (UID 123) with group `rabbitmq' ... Not creating home directory `/var/lib/rabbitmq'. Job for rabbitmq-server.service failed because the control process exited with error code. See "systemctl status rabbitmq-server.service" and "journalctl -xe" for details.

RabbitMQ installation Error

由 二次信任 提交于 2020-12-29 07:09:03
问题 I am installing rabbitMQ on ubuntu16.04. But I am getting below error. I tries searching for it but not able to resolve it. Adding group `rabbitmq' (GID 131) ... Done. Adding system user `rabbitmq' (UID 123) ... Adding new user `rabbitmq' (UID 123) with group `rabbitmq' ... Not creating home directory `/var/lib/rabbitmq'. Job for rabbitmq-server.service failed because the control process exited with error code. See "systemctl status rabbitmq-server.service" and "journalctl -xe" for details.

AI 基础：Scipy（科学计算库） 简易入门

由 空扰寡人 提交于 2020-12-28 11:38:40
0.导语 Scipy是一个用于数学、科学、工程领域的常用软件包，可以处理插值、积分、优化、图像处理、常微分方程数值解的求解、信号处理等问题。它用于有效计算Numpy矩阵，使Numpy和Scipy协同工作，高效解决问题。 Scipy是由针对特定任务的子模块组成： 在此之前，我已经写了以下几篇AI基础的快速入门，本篇文章讲解科学计算库Scipy快速入门： 已发布： AI 基础：Numpy 简易入门 AI 基础：Pandas 简易入门 AI基础：数据可视化简易入门（matplotlib和seaborn） 备注：本文代码可以在github下载 https://github.com/fengdu78/Data-Science-Notes/tree/master/4.scipy 1.SciPy-数值计算库 import numpy as np import pylab as pl import matplotlib as mpl mpl.rcParams['font.sans-serif'] = ['SimHei'] import scipy scipy.__version__#查看版本 '1.0.0' 常数和特殊函数 from scipy import constants as C print (C.c) # 真空中的光速 print (C.h) # 普朗克常数 299792458.0 6

Java Web从前端到后台常用框架介绍

由 拜拜、爱过 提交于 2020-12-26 19:06:12
一、SpringMVC Spring Web MVC是一种基于Java的实现了Web MVC设计模式的请求驱动类型的轻量级Web框架，即使用了MVC架构模式的思想，将web层进行职责解耦，基于请求驱动指的就是使用请求-响应模型，框架的目的就是帮助我们简化开发，Spring Web MVC也是要简化我们日常Web开发的。 模型（Model ） 封装了应用程序的数据和一般他们会组成的POJO。 视图（View） 是负责呈现模型数据和一般它生成的HTML输出，客户端的浏览器能够解释。 控制器（Controller ） 负责处理用户的请求，并建立适当的模型，并把它传递给视图渲染。 Spring的web模型 - 视图 - 控制器（MVC）框架是围绕着处理所有的HTTP请求和响应的DispatcherServlet的设计。 Spring Web MVC处理请求的流程 具体执行步骤如下 ： 1、 首先用户发送请求————>前端控制器，前端控制器根据请求信息（如URL）来决定选择哪一个页面控制器进行处理并把请求委托给它，即以前的控制器的控制逻辑部分；图2-1中的1、2步骤； 2、 页面控制器接收到请求后，进行功能处理，首先需要收集和绑定请求参数到一个对象，这个对象在Spring Web MVC中叫命令对象，并进行验证，然后将命令对象委托给业务对象进行处理；处理完毕后返回一个ModelAndView
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