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POUnderstanding Python fork and memory allocation errors
 

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  1. POUnderstanding Python fork and memory allocation errors
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    <p>I have a memory intensive Python application (between hundreds of MB to several GB).<br> I have a couple of VERY SMALL Linux executables the main application needs to run, e.g.</p> <pre><code>child = Popen("make html", cwd = r'../../docs', stdout = PIPE, shell = True) child.wait() </code></pre> <p>When I run these external utilities (once, at the end of the long main process run) using <code>subprocess.Popen</code> I sometimes get <code>OSError: [Errno 12] Cannot allocate memory</code>.<br> I don't understand why... The requested process is tiny!<br> The system has enough memory for many more shells. </p> <p>I'm using Linux (Ubuntu 12.10, 64 bits), so I guess subprocess calls Fork.<br> And Fork forks my existing process, thus doubling the amount of memory consumed, and fails??<br> What happened to "copy on write"? </p> <p>Can I spawn a new process without fork (or at least without copying memory - starting fresh)?</p> <p>Related:</p> <p><a href="https://stackoverflow.com/questions/4856255/the-difference-between-fork-vfork-exec-and-clone">The difference between fork(), vfork(), exec() and clone()</a></p> <p><a href="https://stackoverflow.com/questions/12924048/fork-memory-allocation-behavior">fork () &amp; memory allocation behavior</a></p> <p><a href="https://stackoverflow.com/questions/1216794/python-subprocess-popen-erroring-with-oserror-errno-12-cannot-allocate-memory">Python subprocess.Popen erroring with OSError: [Errno 12] Cannot allocate memory after period of time</a></p> <p><a href="https://stackoverflow.com/questions/5306075/python-memory-allocation-error-using-subprocess-popen">Python memory allocation error using subprocess.Popen</a></p>
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    1. CO[Have you read this answer to the related question](http://stackoverflow.com/a/13329386/4279)?
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    2. COI have, thanks. There are some valuable workarounds there, some of which I may use. I was hoping for a real solution - the ability to spawn a new process from within Python that does not copy all the process memory a la fork.
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