handle error in find_library

examples/DeepQNetwork/README.md

@@ -18,7 +18,7 @@ used a modified version where each batch contains transitions from different sim
 ## Usage:
 
 ### With ALE (paper's setting):
-Install [ALE](https://github.com/mgbellemare/Arcade-Learning-Environment) and gym.
+Install [ALE](https://github.com/mgbellemare/Arcade-Learning-Environment) and `gym[atari]`.
 
 Download an [atari rom](https://github.com/openai/atari-py/tree/gdb/atari_py/atari_roms), e.g.:
 ```

tensorpack/utils/utils.py

@@ -251,6 +251,7 @@ def find_library_full_path(name):
         procmap = os.path.join('/proc', str(os.getpid()), 'maps')
         if not os.path.isfile(procmap):
             return None
+        try:
             with open(procmap, 'r') as f:
                 for line in f:
                     line = line.strip().split(' ')
@@ -260,6 +261,10 @@ def find_library_full_path(name):
                     if 'lib' + name + '.so' in basename:
                         if os.path.isfile(sofile):
                             return os.path.realpath(sofile)
+        except PermissionError:
+            # can fail in certain environment (e.g. chroot)
+            # if the pids are incorrectly mapped
+            pass
 
     # The following two methods come from https://github.com/python/cpython/blob/master/Lib/ctypes/util.py
     def _use_ld(name):