Python ctypes MemoryError in fcgi process from PIL

问题:

I'm trying to run Django on shared hosting (Bluehost). I'm using functionality that requires PIL. PIL imports and works from an interactive shell, but in my fcgi process it crashes with a MemoryError at from PIL import image. Any help on why it might be failing inside fcgi would be much appreciated.

__Environment Info__:  
Python2.7

Local installs of libjpg, zlib, freetype, and lcms

Virtualenv:  
Django 1.3, PIL, flup, etc.

__Stack Trace__:  

    File ".../feincms_thumbnail.py", line 3, in <module>  
        from PIL import Image

    File ".../PIL/Image.py", line 45, in <module>  
        \__import__("FixTk")

    File ".../python2.7/lib-tk/FixTk.py", line 15, in <module>  
        import ctypes

    File ".../python2.7/ctypes/__init__.py", line 549, in <module>  
        CFUNCTYPE(c_int)(lambda: None)

__.fcgi__:  

<!-- language: python -->
    # setup paths
    # set DJANGO_SETTINGS_MODULE in os.environ  

    from django.core.servers.fastcgi import runfastcgi  
    runfastcgi(method="threaded", daemonize="false")

回答1:

I have temporarily fixed that error commenting the last line in this file $HOME/lib/python2.7/ctypes/__init__.py that is something like #CFUNCTYPE(c_int)(lambda: None).

That's work for me, but i don't know what exactly the problem is.

UPDATE

In python 2.7.3 the line number is :279 not the last as I said above.

UPDATE 2 Since the line may vary between minor versions, you should look for a chunk of code that looks something like this:

# XXX for whatever reasons, creating the first instance of a callback
# function is needed for the unittests on Win64 to succeed.  This MAY
# be a compiler bug, since the problem occurs only when _ctypes is
# compiled with the MS SDK compiler.  Or an uninitialized variable?
CFUNCTYPE(c_int)(lambda: None)

回答2:

try running this command:

setsebool -P httpd_tmp_exec on

fixes things for me on CentOS. Taken from this post: https://bugzilla.redhat.com/show_bug.cgi?id=645193

回答3:

Just to expand on eos87's answer a bit, this does fix the problem for me as well, and judging by the comment before that line, it sounds like it was added as a workaround to a windows bug, but the workaround is apparently causing trouble of its own. Here's the bit at the end of __init__.py:

# XXX for whatever reasons, creating the first instance of a callback
# function is needed for the unittests on Win64 to succeed.  This MAY
# be a compiler bug, since the problem occurs only when _ctypes is
# compiled with the MS SDK compiler.  Or an uninitialized variable?
CFUNCTYPE(c_int)(lambda: None)

It looks like it's safe to remove.

FWIW, this issue showed up for me on a Centos 5.7 x64 box when using python 2.6 as installed (in parallel with python 2.4) from epel. The file was found here: /usr/lib64/python2.6/ctypes/__init__.py

Also note that the exception that shows up is a MemoryError which according to strace results from a segmentation fault immediately (though perhaps coincidentally) after a call to munmap; and it only shows up when running as FastCGI.