umfpack error

[Juan Nunez-Iglesias]

Ok so I'm having trouble actually suppressing this thing. The problem is
that to detect whether umfpack is present we try to build the
UmfpackContect() object:

try:
    from scipy.sparse.linalg.dsolve import umfpack
    UmfpackContext = umfpack.UmfpackContext()except:
    UmfpackContext = None


The constructor raises an ImportError, which we duly catch (although that
line should really specify the error type, but whatever). Unfortunately,
the UmfpackContext class has a destructor (__del__) which then tries to
delete some objects that were never created and raises an AttributeError —
which, since we are already in a try: except: clause, gets ignored, hence
the message to stderr.

Basically this is a bug in scipy I think?

The standard approach is to temporarily redirect stderr to /dev/null, and
this works interactively:

In [1]: from scipy.sparse.linalg.dsolve import umfpack

In [2]: try:
    UC = umfpack.UmfpackContext()except ImportError:
    print 'hello'
   ...:
hello
Exception AttributeError: "'UmfpackContext' object has no attribute
'_symbolic'" in <bound method UmfpackContext.__del__ of
<scipy.sparse.linalg.dsolve.umfpack.umfpack.UmfpackContext object at
0x103938250>> ignored

In [3]: import sys, os

In [4]: null = open(os.devnull, 'w')

In [5]: null.write('hello!')

In [6]: sys.stdout.write('hello!')
hello!
In [7]: sys.stderr.write('hello')
hello
In [8]: sys.stderr = null

In [9]: sys.stderr.write('hello')

In [10]: try:
    UC = umfpack.UmfpackContext()except ImportError:
    print 'hello'
   ....:
hello

In [11]: sys.stderr = sys.__stderr__

In [12]: sys.stderr.write('hello')
hello


However, doing this in the code doesn't work, even when I try to flush the
redirected stderr! (I'm not even sure that makes sense!)

sys.stderr = open(os.devnull, 'w')try:
    from scipy.sparse.linalg.dsolve import umfpack
    UmfpackContext = umfpack.UmfpackContext()except:
    UmfpackContext = Nonefinally:
    sys.stderr.flush()
    sys.stderr = sys.__stderr__


Thoughts/ideas?



On Fri, Oct 4, 2013 at 10:54 PM, Juan Nunez-Iglesias <jni.soma at gmail.com>wrote:

> Thanks! Although in this case I was using pip install *and* it was on an
> EC2 micro instance so I only have 1 CPU. =)
>
> But it is noted and very useful going forward. =)
>
>
>
> On Fri, Oct 4, 2013 at 10:32 PM, Ralf Gommers <ralf.gommers at gmail.com>wrote:
>
>>
>>
>>
>> On Fri, Oct 4, 2013 at 1:33 PM, Juan Nunez-Iglesias <jni.soma at gmail.com>wrote:
>>
>>> On Fri, Oct 4, 2013 at 8:59 PM, Johannes Schönberger <jsch at demuc.de>wrote:
>>>
>>>> Are you sure you have SWIG installed?
>>>>
>>>
>>> I wasn't and I didn't. =)
>>>
>>> Bloody hell scipy takes a long time to build. =)
>>>
>>
>> $ time python setup.py build_ext -i
>> real    12m6.843s
>> user    6m3.244s
>> sys     0m13.124s
>>
>> $ time ../Bento/bentomaker build -i -j   # -j == parallel build (on 4
>> cores here)
>> real    1m46.466s
>> user    2m54.628s
>> sys     0m10.900s
>>
>> Blame distutils (and start using Bento) :)
>>
>> Ralf
>>
>>
>>
>>
>>>  Juan.
>>>
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