打开与在C程序的fopen（多线程） [英] open versus fopen in C program (with multi-threading)

问题描述

对于未知的原因，似乎FOPEN无法打开文本文件时它被关闭之前调用重复次数。

For an unknown reason, it seems that fopen fails to open text files when it is called repeated times before closing.

我的C程序使用多线程，每个线程处理一种类型的输出文本文件（此处为十每型），每种类型在一个分离的文件夹中。我需要为了写大量的数据，以十个分量这些文件中较长的执行，并在同一个线程中打开。

My C program uses multithreading, and each thread handles one type of output text files (eleven per type), each type in a separated folder. I need to mantain these files opened during a long execution and at the same thread in order to write a lot of data.

要更好地解释它，这个过程是这样的：

To explain it better, the process is the following:

1线程＃1开始并创建和一个文件夹中写道：11档。

1- Thread #1 starts and creates and writes 11 files in one folder.

2 - 不关闭在不同的文件夹previous文件，线程＃2开始，然后创建并写入另一个11个文件。

2- Without closing previous files, Thread #2 starts and creates and writes another 11 files in a different folder.

3与其他两个线程一样的。

3- The same with other two Threads.

4-最后，当所有需要的已创建和文件中的所有线程都完成，除非主要的一个，所有的文件被关闭。

4- In the end, when all the files needed have been created and all the Threads have finished unless the main one, all the files are closed.

然而，令人惊讶的，开放的是做能够处理所有这文件在同一时间。是否有人有一个关于这个问题有FOPEN小费？我不知道这是否是与多线程或文件的最大数量的fopen可以同时处理相关

However and surprisingly, open is do able to handle all this files at the same time. Does anybody have a tip about this issue with fopen? I don't know if it is related with the multi-threading or with a max number of files that fopen can handle at the same time.

我在Windows平台上用Borland的编译器。

I am in Windows platform with Borland compiler.

推荐答案

C运行时（CRT）库是线程从Windows XP及以上安全。另外，如果你相信一些在CRT的意见，包括文件，它有20打开文件的限制。

The C Run Time (CRT) library is thread safe from Windows XP and above. Also, if you believe some of the comments in the CRT include files, it has a limit of 20 open files.

所以，在你的应用程序。什么是单线程的原因有11个文件打开？你是不会被同时写入他们获得可观的性能增益。事实上，你可以使情况变得更糟，因为C盘将捶打，因为它绕着试图写入每个文件。

So, in your application. What is the reason for a single thread to have 11 files open? You are NOT going to get a measurable performance gain by writing them simultaneously. In fact, you could make it worse because the C drive will thrash as it moves around trying to write each file.

根据您的应用程序如何设计：打开一个文件，写它满为止，关闭它，打开第二个文件，等等。

Depending on how your application is designed: open one file, write to it until full, close it, open second file, etc.

现在，乘以4盘抖动的可能，因为每个线程试图做I / O相同的C盘！所以，如果序列化可能的磁盘访问。得到真正的改善增加了缓冲区的大小。

Now, multiply the possibility of disk thrashing by four as each thread is trying to do I/O to the same C drive! So, serialize disk accesses if possible. to get a real improvement increase the buffer sizes.

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