matplotlib · tacaswell · Jul 25, 2016 · Jul 17, 2016 · Jul 19, 2016
diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
@@ -2577,10 +2577,11 @@ def _putmask(a, mask, values):
        return np.copyto(a, values, where=mask)

 _lockstr = """\
-LOCKERROR: matplotlib is trying to acquire the lock {!r}
+LOCKERROR: matplotlib is trying to acquire the lock
+    {!r}
 and has failed.  This maybe due to any other process holding this
-lock.  If you are sure no other matplotlib process in running try
-removing this folder(s) and trying again.
+lock.  If you are sure no other matplotlib process is running try
+removing these folders and trying again.
 """


@@ -2598,6 +2599,9 @@ class Locked(object):
    """
    LOCKFN = '.matplotlib_lock'

+    class TimeoutError(RuntimeError):
+        pass
+
    def __init__(self, path):
        self.path = path
        self.end = "-" + str(os.getpid())
@@ -2607,18 +2611,17 @@ def __init__(self, path):

    def __enter__(self):
        retries = 50
-        sleeptime = 1
+        sleeptime = 0.1
        while retries:
            files = glob.glob(self.pattern)
            if files and not files[0].endswith(self.end):
                time.sleep(sleeptime)
-                sleeptime *= 1.1
                retries -= 1
            else:
                break
        else:
            err_str = _lockstr.format(self.pattern)
-            raise RuntimeError(err_str)
+            raise self.TimeoutError(err_str)

        if not files:
            try:

diff --git a/lib/matplotlib/font_manager.py b/lib/matplotlib/font_manager.py
@@ -1446,6 +1446,8 @@ def _rebuild():
            else:
                fontManager.default_size = None
                verbose.report("Using fontManager instance from %s" % _fmcache)
+        except cbook.Locked.TimeoutError:
+            raise
        except:
            _rebuild()
    else: