Segmentation Fault, Worker crashed on signal SIGSEGV ?

Fatal Python error: Segmentation fault

Current thread 0x00007fffb313d3c0 (most recent call first):
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/json/encoder.py", line 412 in _make_iterencode
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/json/encoder.py", line 256 in iterencode
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/json/encoder.py", line 199 in encode
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/json/__init__.py", line 238 in dumps
  File "/usr/local/lib/python3.6/site-packages/pydruid/client.py", line 409 in _post
  File "/usr/local/lib/python3.6/site-packages/pydruid/client.py", line 141 in timeseries
  File "japronto_visuG.py", line 50 in visuG
  File "/usr/local/lib/python3.6/site-packages/japronto/app/__init__.py", line 182 in serve
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/multiprocessing/process.py", line 93 in run
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/multiprocessing/process.py", line 249 in _bootstrap
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/multiprocessing/popen_fork.py", line 74 in _launch
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/multiprocessing/popen_fork.py", line 20 in __init__
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/multiprocessing/context.py", line 277 in _Popen
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/multiprocessing/context.py", line 223 in _Popen
  File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/multiprocessing/process.py", line 105 in start
  File "/usr/local/lib/python3.6/site-packages/japronto/app/__init__.py", line 228 in _run
  File "/usr/local/lib/python3.6/site-packages/japronto/app/__init__.py", line 264 in run
  File "japronto_visuG.py", line 236 in <module>
Worker crashed on signal SIGSEGV!