dynamic link library

Dynamic-Link Libraries (Windows) https://msdn.microsoft.com/en-us/library/windows/desktop/ms682589(v=vs.85).aspx

dynamic-link library (DLL) is a module that contains functions and data that can be used by another module (application or DLL).

A DLL can define two kinds of functions: exported and internal. The exported functions are intended to be called by other modules, as well as from within the DLL where they are defined. Internal functions are typically intended to be called only from within the DLL where they are defined. Although a DLL can export data, its data is generally used only by its functions. However, there is nothing to prevent another module from reading or writing that address.

DLLs provide a way to modularize applications so that their functionality can be updated and reused more easily. DLLs also help reduce memory overhead when several applications use the same functionality at the same time, because although each application receives its own copy of the DLL data, the applications share the DLL code.

The Windows application programming interface (API) is implemented as a set of DLLs, so any process that uses the Windows API uses dynamic linking.

● 600 万行C++代码

● 50,000多个类

● 代码中使用的C++方法早已过时,而且受限于一个编译器版本,该编译器版本仅支持一个不再维护的操作系统。

● 基于CORBA

● 采用一家倒闭公司提供的数据库软件

● 多层的叠加共同组成了用户界面,但却没有一个是实际作者在维护的。

● 在32台并行的机器上编译需要48小时。

● 运行一个用户界面需要同步启动40~50个子进程

● 没有动态库链接:可执行的文件大小一个就有几百兆

● 启动时间需要耗费15分钟

● 平均崩溃时间:30秒到30分钟不等

A few years ago, I was hired to work as a consultant on a software project for a large French tech company. What I have witnessed there is beyond everything I could possibly have imagined in terms of software engineering. Far more serious than just a lack of professional competence was the utmost contempt for human dignity which at some point made me compare the whole experience to (what I imagine can be) jail. What I relate here is a selected list of topics that should illustrate my point, but check out by yourself.

Scope

Develop a piece of software for a government agency.
Low complexity, with a few twists.

Government pays a few million Euros upfront, development is scheduled for two to three years. Company hires a couple of developers to start the job, and keeps doubling team size every 3 months or so as cash starts flowing in.

7 years later, the project is still not in any decent shape.  Penalties are running in several thousand Euros per day.  Management decides to reduce costs and fires all experimented people, hires people with little or no software experience.

10 years later, given the disastrous state of the project, middle-management decides to hire some people with software engineering experience to get back on tracks. Average turn-over for the newcomers: 3 months, the legal time to leave your job in France.

12 years later, the project is still active. The company recovers daily penalties by billing ever-increasing change requests to the government. The year is 2008.

Figures

  • million lines of code
  • C++ based
  • 50,000+ classes
  • C++ flavour in use is obsolete, locked into compiler version, which is only distributed with one (unmaintained) Operating System.
  • CORBA-based
  • Database software from a company gone bankrupt
  • Several layers on top of each other to handle the Graphical User Interface, none of which actually maintained by the authors.
  • Build takes 48 hours on 32 parallel machines.
  • 40 to 50 simultaneous processes needed to run one User Interface
  • No dynamic library linking: executable sizes in the range of several hundred megabytes
  • Startup time is about 15 minutes
  • Mean time between crashes: 30 seconds to 30 minutes

No software engineer will tell you that C++ is an easy language.  In fact, it is probably one of the worst computer languages in terms of complexity. It is actually so complex that even its creators admit that they still do not master all of it. See a famous spoof Stroustrup interview here:
http://www-users.cs.york.ac.uk/~susan/joke/cpp.htm

Faced with such an incredible maze of bottomless complexity, people tend to react in a different way. The geek wannabees have all heard about C++ and want to show that they can do it too.  They dive into it without fear and get maimed beyond recognition, spending countless hours trying to figure out how a pageful of gobbledygook crashes endlessly without apparent reason.  People with more sense quickly turn to other languages and other projects. Life is too short.

Maintaining a large body of software in any language is a hard task. Imagine a team having to maintain 6 MILLION LINES of code and you get an idea of how far insanity can reach in the realm of software engineering. 6 million is a big number: if you wanted to read all the lines quickly at one per second, you would spend about seventy days non-stop in front of your screen.

Just to give you a taste, here are two anecdotes:

One developer was given the task of checking why right-clicking on the interface completely froze the application. After several days of careful examination and incredible amounts of patience, he found out that right-clicking worked fine, only that it took about 45 minutes for the context menu to popup. Menus were all dynamically generated from huge (static!) content every time you right-clicked the main window.

At some point end-users reported that “Load data from CD-ROM” did not work at all. This one took several weeks to sort out, but in the end the bug report was flagged as ‘already solved’, because data were indeed being loaded. The only point was that it took 7 straight days for 700 MBytes to get in. Patience is a virtue.

Version Control gone wild

It took several years until one bright guy in the team came up with the idea of using version control tools. First attempt was not convincing, so the team switched to another system, then another a couple of years later, losing all history with each change.

The tool that was finally chosen is a disaster with a graphical user interface, an abomination coming directly from Sweden. A team of four people is actually dedicated full-time to performing most maintenance issues on the version control software, which gives things like:

  • Doing a first checkout requires taking an appointment with the version control team, usually granted a week later.
  • Editing files is not permitted without authorization from middle management. You have to tell your manager in advance which files you want to edit, then send an official permission request which gets filed with the version control team who may take action within a couple of days.
  • Every modification of the code triggers branching, which means you have to merge back all modifications you receive. With so many files in store you may think that two people working on the same file would be rare, but it turned out that most work happened within the same 100 files or so.
  • Check-in needs to go through a painful procedure whereby your code is reviewed by automagic bug-detecting software and eventually by middle management. Needless to say, this does not prevent bugs from creeping in faster than developers can remove them. A closer look at the number of registered bugs showed that every defect correction brought in twice as many bugs as it corrected.
  • Versioning is simple. Old software is version 1, today’s software is version 2, software in the future is version 3.  Nobody can actually tell which version has been delivered to the customer.

At some point, an official delivery was scheduled, totally independent from any kind of planning set within the team. When the day came, the customer was actually sent a blank CD with installation instructions because nobody had been able to build the software in weeks. The customer found out they had been delivered a blank CD, officially complained, and was given an old version to replace the previous delivery. They found out because the displayed date in the “About” box was the same as last year.

Peopleware

Pay peanuts, get monkeys.

With a large number of people without any software engineering experience, is it really a surprise that bugs keep creeping in in vast numbers? A really bright manager must have realized that human costs were the main source of cost in a pure software project. Not at all deterred by this extraordinary discovery, he decided to fire all people with any kind of experience but keep all managers in. It was not uncommon to see “C++ for dummies” on many people’s desks.

Meet the Team

55 people in the team: 20 developers, 35 managers.
That’s right: more managers than actual developpers.
Managers keep organizing meetings where they show the same PowerPoint presentation over and over ad nauseam, while developers kill time by chatting in the vast open-space office.
Few managers have any experience with software engineering. At that time SCO was suing IBM about Linux. Even if the whole thing was a bluff, it really worked with such people who all understood that they had to pay soon for Free Software.  None of them ever mentions ‘Software Libre’, but they all know about ‘Software Gratuit’. Needless to say, the project is peppered with GNU libraries all over the place and these guys have absolutely no idea this turns the whole thing into a vast unshared GNU-compliant project. But hey, given the abysmal quality of this thing, nobody will ever insist that they release the sources.

Technical knowledge is low. Few people know about Internet, those who do think it is only made for porn. Mentioning you have seen something on the Internet brings you winks and smiles.

Welcome to Hell

The whole experience could have been funny if the top management had not decided to behave like nazis in a concentration camp. Just to give some examples:

  • It is forbidden to come to work after 9am. One day, the site manager stayed behind the main gates and fired on the spot every person who came in after 9.01am, including a number of managers and sales.
  • Smokers take more pauses so produce less. Management tried to force everybody to stop smoking by coercion. Did not work.
  • Coffee machines are regularly out of order for several days. Somebody who drinks coffee is less productive than somebody sitting at his desk, typing away precious lines of code.
  • The same coffee machines are switched off whenever officials come to visit the site, to give the impression that everybody is at work.
  • Toilets are the most disgusting I have ever seen. The idea is probably to increase productivity: spend less time in the loo, you work more (and better).

You are probably wondering now why people kept coming to work in such an environment. The first and main reason was the deep economy crisis France was going through at that time (and still is today, to a certain extent).  Having a job and a salary was considered a privilege, no matter what conditions were attached.

Another reason was that for many, this contract was the first they ever got with a real company. Without any reference it is impossible to gauge how much your job sucks. Most beginners thought it was perfectly normal to be forced to be there at 9am sharp or be fired, when absolutely nothing imposed such a constraint except the sick mind of a manager.
As to how a government can let such things happen: we all know how it works. The guys in charge of budget at the ministery are pals with the top-management in a number of companies. In a country like France, corruption is not uncommon at that level, goes mostly undiscovered and is rarely prosecuted. Apparently this is not reserved to France. I have heard the same stories a little bit everywhere in Europe and the US.

Next time you think your job sucks, think again.

Relevant sites:

没有动态库链接:可执行的文件大小一个就有几百兆 Dynamic-Link Libraries的更多相关文章

  1. 动态库连接器–动态库链接信息(Mach-O文件格式和程序从加载到执行过程)

    section cmd 说明 举例 __text 主程序代码   __stubs 用于动态库链接的桩   __stub_helper 用于动态库链接的桩   __cstring 常亮字符串符号表描述信 ...

  2. 深入理解LINUX下动态库链接器/加载器ld-linux.so.2

    [ld-linux-x86-64.so.2] 最近在Linux 环境下开发,搞了好几天 Compiler 和 linker,觉得有必要来写一篇关于Linux环境下 ld.so的文章了,google上搜 ...

  3. GCC同时使用静态库和动态库链接

    一 在应用程序需要连接外部库的情况下,linux默认对库的连接是使用动态库,在找不到动态库的情况下再选择静态库.使用方式为: gcc test.cpp -L. -ltestlib 如果当前目录有两个库 ...

  4. makefile与动态链接库案例分析——动态库链接动态库

    http://blog.csdn.net/huqinwei987/article/details/50517780 背景:效率考虑,要重用把服务器主备机方案,以库Libmdpha(高可用)的形式加进主 ...

  5. 【未完待补充】linux 设置So动态库链接路径

    缘起 安装python的包Rtree(Rtree-0.8.2),但需要先安装C语言依赖包spatialindex-src(spatialindex-src-1.8.5).在安装完spatialinde ...

  6. Linux下包含头文件的路径问题与动态库链接路径问题

    C/C++程序在linux下被编译和连接时,GCC/G++会查找系统默认的include和link的路径,以及自己在编译命令中指定的路径.自己指定的路径就不说了,这里说明一下系统自动搜索的路径. [1 ...

  7. Linux程序编译链接动态库版本号的问题

    不同版本号的动态库可能会不兼容,假设程序在编译时指定动态库是某个低版本号.执行是用的一个高版本号,可能会导致无法执行. Linux上对动态库的命名採用libxxx.so.a.b.c的格式.当中a代表大 ...

  8. Linux系统中“动态库”和“静态库”那点事儿 /etc/ld.so.conf 动态库的后缀为*.so 静态库的后缀为 libxxx.a ldconfig 目录名

    Linux系统中“动态库”和“静态库”那点事儿 /etc/ld.so.conf  动态库的后缀为*.so  静态库的后缀为 libxxx.a   ldconfig   目录名 转载自:http://b ...

  9. WWDC2014之iOS使用动态库 framework【转】

    from:http://www.cocoachina.com/industry/20140613/8810.html JUN 12TH, 2014 苹果的开放态度 WWDC2014上发布的Xcode6 ...

随机推荐

  1. MySQL存储过程的创建及调用

    阅读目录:MySQL存储过程_创建-调用-参数 存储过程:SQL中的“脚本” 1.创建存储过程 2.调用存储过程 3.存储过程体 4.语句块标签 存储过程的参数 1.in:向过程里传参 2.out:过 ...

  2. centos7安装python-3.5

    sudo yum install gcc wget https://www.python.org/ftp/python/3.5.0/Python-3.5.0.tgz sudo cp Python-.t ...

  3. Kafka producer介绍

    Kafka 0.9版本正式使用Java版本的producer替换了原Scala版本的producer.本文着重讨论新版本producer的设计原理以及基本的使用方法. 新版本Producer 首先明确 ...

  4. springboot 集成elasticsearch5.4.3

    官网上对elasticsearch 的集成用的是spring-data,而且,暂时不支持5.x的版本, 要是想集成5.x的版本,我们只能在pom.xml文件中进行修改,如图: <project ...

  5. delphi调用存储过程

    一 . TAdoQuery对象下 1. mysql存储过程 sqls := Format(' call pro_addOneStudent (' + '''%s'',''%s'',''%s'',''% ...

  6. codeforces水题100道 第十二题 Codeforces Beta Round #91 (Div. 2 Only) A. Lucky Division (brute force)

    题目链接:http://www.codeforces.com/problemset/problem/122/A题意:判断一个数是否能被一个lucky number整除,一个lucky number是一 ...

  7. 如何将一个项目打成war包?

    如何将一个项目打成war包?进入该项目所在目录jar  -cvf  myProjec.war  myProject

  8. iOS - UITextView实现placeHolder占位文字

      iOS之UITextView实现placeHolder占位文字的N种方法 前言 iOS开发中,UITextField和UITextView是最常用的文本接受类和文本展示类的控件.UITextFie ...

  9. 基于链表的C语言堆内存检测

    说明 本文基于链表实现C语言堆内存的检测机制,可检测内存泄露.越界和重复释放等操作问题. 本文仅提供即视代码层面的检测机制,不考虑编译链接级的注入或钩子.此外,该机制暂未考虑并发保护. 相关性文章参见 ...

  10. MFC onchar()

    为什么在CView类中可以对ON_CHAR进行相应,添加消息处理函数onchar就可以了,但是在CDialog中要对ON_CHAR相应,直接添加不行? CView相当于Text控件,你可以在Text控 ...