ValueError: semaphore or lock fired too many times?

Question

I get ValueError: semaphore or lock released too many times when I try to do pip install matplotlib in Cygwin. What should I do?

UPDATE:

 $ pip install matplotlib Downloading/unpacking matplotlib You are installing an externally hosted file. Future versions of pip will default to disallowing externally hosted files. You are installing a potentially insecure and unverifiable file. Future versions of pip will default to disallowing insecure files. Downloading matplotlib-1.3.0.tar.gz (42.1MB): 42.1MB downloaded Running setup.py egg_info for package matplotlib ============================================================================ Edit setup.cfg to change the build options BUILDING MATPLOTLIB matplotlib: yes [1.3.0] python: yes [2.7.5 (default, Jul 30 2013, 14:34:22) [GCC 4.8.1]] platform: yes [cygwin] REQUIRED DEPENDENCIES AND EXTENSIONS numpy: yes [version 1.7.1] dateutil: yes [using dateutil version 2.1] tornado: yes [tornado was not found. It is required for the WebAgg backend. pip/easy_install may attempt to install it after matplotlib.] pyparsing: yes [pyparsing was not found. It is required for mathtext support. pip/easy_install may attempt to install it after matplotlib.] pycxx: yes [Couldn't import. Using local copy.] libagg: yes [pkg-config information for 'libagg' could not be found. Using local copy.] freetype: yes [version 16.1.10] png: yes [version 1.5.14] OPTIONAL SUBPACKAGES sample_data: yes [installing] toolkits: yes [installing] tests: yes [nose 0.11.1 or later is required to run the matplotlib test suite] OPTIONAL BACKEND EXTENSIONS macosx: no [Mac OS-X only] qt4agg: no [PyQt4 not found] Process PoolWorker-1: Traceback (most recent call last): File "/usr/lib/python2.7/multiprocessing/process.py", line 258, in _bootstrap self.run() File "/usr/lib/python2.7/multiprocessing/process.py", line 114, in run self._target(*self._args, **self._kwargs) File "/usr/lib/python2.7/multiprocessing/pool.py", line 102, in worker task = get() File "/usr/lib/python2.7/multiprocessing/queues.py", line 378, in get rrelease() ValueError: semaphore or lock released too many times 

Answer 1

I am not sure if this is a problem with the latest (stable) matplotlib build, but I ran into the same problem.

My solution was to install an older stable version ( 1.2.1 ).

Download tar file 1.2.1 , unzip and install. Do not use when configuring the cygwin compiler. those.

  python setup.py build --compiler=cygwin 

will fail (for me) but the usual

  python setup.py build 

will work. Of course you will need to keep track of

  python setup.py install 

Note: I am running quite recent cygwin64. I have already installed all the dependencies. I also tried installing 1.3.0 via pip as well as source . Both threw the exact same error you described here.

Answer 2

Try updating the "cygwin" package to version 1.7.26 ( http://cygwin.1069669.n5.nabble.com/Problem-with-multiprocessing-module-from-Python-td103816.html ).