I was having some trouble running conformance tests on Windows:
https://bugs.chromium.org/p/chromium/issues/detail?id=596241

After watching many failures from running:
"""
D:\projects\chromium\src>python .\content\test\gpu\run_gpu_test.py webgl_conformance --story-filter=conformance_more_functions
"""

I tried to <Ctr-C> out of it. This led to the same failure message repeated hundreds of times. Eventually, I was able to get it to stop by <Ctr-C>ing many times, in quick succession.

"""
Traceback (most recent call last):
  File "D:\projects\chromium\src\third_party\catapult\telemetry\telemetry\core\local_server.py", line 176, in Close
    server.Close()
  File "D:\projects\chromium\src\third_party\catapult\telemetry\telemetry\core\local_server.py", line 127, in Close
    self._subprocess.kill()
  File "C:\python_27_amd64\files\lib\subprocess.py", line 1019, in terminate
    _subprocess.TerminateProcess(self._handle, 1)
WindowsError: [Error 5] Access is denied
"""

I'm guessing that under exceptional circumstances, there's an infinite loop?
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/catapult/telemetry/telemetry/core/local_server.py&q=local_server.py&sq=package:chromium&type=cs&l=174