MATLAB中的信号量和锁 [英] Semaphores and locks in MATLAB

问题描述

我正在研究一个MATLAB项目，在该项目中，我想让两个MATLAB实例并行运行并共享数据.我将这些实例称为MAT_1和MAT_2.更具体地说，系统的体系结构是:

I am working on a MATLAB project where I would like to have two instances of MATLAB running in parallel and sharing data. I will call these instances MAT_1 and MAT_2. More specifically, the architecture of the system is:

1. MAT_1依次处理图像，使用imread逐个读取它们，并使用imwrite输出每个图像的结果.
2. MAT_2使用imread读取MAT_1输出的图像，并将其结果输出到其他位置.

1. MAT_1 processes images sequentially, reading them one by one using imread, and outputs the result for each image using imwrite.
2. MAT_2 reads the images output by MAT_1 using imread and outputs its result somewhere else.

我想我要解决的问题之一是确保MAT_2完全完成对MAT_1的输出后，才能读取MAT_1的图像.

One of the problems I think I need to address is to guarantee that MAT_2 reads an image output by MAT_1 once MAT_1 has fully finished writing to it.

我的问题是:

1. 您将如何解决这个问题?我是否需要使用信号灯或锁来防止出现竞争状况?
2. MATLAB是否提供任何锁定文件的机制? (即类似于 flock 的内容，但直接由MATLAB提供，并且可以在多种平台(例如Windows和Linux)上运行.如果不是，您是否知道我可以用来在MATLAB中构建此机制的任何第三方库?

• 正如@yoda在下面指出的那样，并行计算工具箱(PCT)可以阻止MATLAB工作者之间的调用，这很棒.就是说，我对不需要PCT的解决方案特别感兴趣.

• 为什么需要MAT_1和MAT_2才能在并行线程中运行?:

  EDIT :

  • As @yoda points out below, the Parallel Computing Toolbox (PCT) allows for blocking calls between MATLAB workers, which is great. That said, I am particularly interested in solutions that do not require the PCT.

  • Why do I require MAT_1 and MAT_2 to run in parallel threads?:

    在MAT_2中完成的处理平均比MAT_1慢(并且更容易崩溃)，并且MAT_1的输出为不需要等待的其他程序和过程(包括人工检查)提供了支持. MAT_2来完成其工作.

    The processing done in MAT_2 is slower on average (and more prone to crashing) than MAT_1, and the output of MAT_1 feeds other programs and processes (including human inspection) that do not need to wait for MAT_2 to do its job.

    • 有关允许实现信号量但不依赖PCT的解决方案，请参见下面的乔纳斯(Jonas)的回答
    • 有关解决该问题的其他好的方法，请参见下文Yoda的答案

    推荐答案

    我个人将使用并行处理工具箱.

    Personally, I'd use the parallel processing toolbox for this.

    据我所知，在Matlab中没有简单的方法来拥有系统范围的文件锁.但是，为了确保在文件完成写入后，Matlab#2仅读取Matlab#1的输出，我建议在写入例如文件results_1.mat之后，Matlab#1写入第二个文件results_1.finished，即一个空的文本文件.由于第二个文件是在第一个文件之后写入的，因此它的存在表明结果文件已被写入.因此，您可以搜索扩展名为finished(即dir('*.finished'))的文件，并使用fileparts来获取要通过Matlab#2加载的.mat文件的名称.

    As far as I know, there is no straightforward way in Matlab to have systemwide file locks. However, in order to ensure that Matlab #2 only reads output of Matlab #1 when the file has finished writing, I suggest that after writing e.g the file results_1.mat, Matlab #1 writes a second file, results_1.finished, which is an empty text file. Since the second file is written after the first, its existence signals that the results-file has been written. You can thus search for files with the extension finished, i.e. dir('*.finished'), and use fileparts to get the name of the .mat file you'd like to load with Matlab #2.

    这篇关于MATLAB中的信号量和锁的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！