_tokenPool KeyError in deviceShadow

Using AWSIoTPythonSDK==1.4.3, I’ve caught a KeyError exception inside core.shadow.deviceShadow

 2020-06-10 16:27:50,104 [INFO] AWSIoTPythonSDK.core.protocol.mqtt_core: Performing sync publish...
 Exception in thread Thread-3:
 Traceback (most recent call last):
   File "/usr/local/lib/python3.7/threading.py", line 926, in _bootstrap_inner
     self.run()
   File "/usr/local/lib/python3.7/threading.py", line 870, in run
     self._target(*self._args, **self._kwargs)
   File "/usr/local/lib/python3.7/site-packages/paho/mqtt/client.py", line 2913, in _thread_main
     self.loop_forever(retry_first_connection=True)
   File "/usr/local/lib/python3.7/site-packages/paho/mqtt/client.py", line 1578, in loop_forever
     rc = self.loop(timeout, max_packets)
   File "/usr/local/lib/python3.7/site-packages/paho/mqtt/client.py", line 1072, in loop
     rc = self.loop_read(max_packets)
   File "/usr/local/lib/python3.7/site-packages/paho/mqtt/client.py", line 1374, in loop_read
     rc = self._packet_read()
   File "/usr/local/lib/python3.7/site-packages/paho/mqtt/client.py", line 2071, in _packet_read
     rc = self._packet_handle()
   File "/usr/local/lib/python3.7/site-packages/paho/mqtt/client.py", line 2560, in _packet_handle
     return self._handle_publish()
   File "/usr/local/lib/python3.7/site-packages/paho/mqtt/client.py", line 2759, in _handle_publish
     self._handle_on_message(message)
   File "/usr/local/lib/python3.7/site-packages/paho/mqtt/client.py", line 2902, in _handle_on_message
     callback(self, self._userdata, message)
   File "/opt/awsiot-bridge/src/awsiot-bridge.py", line 492, in on_modbus_complete
     device_shadow_handler.shadowUpdate(connected=True)
   File "/opt/awsiot-bridge/src/shadowmanger.py", line 76, in shadowUpdate
     self.client.shadowUpdate(payload_template, self._update, timeout)
   File "/usr/local/lib/python3.7/site-packages/AWSIoTPythonSDK/core/shadow/deviceShadow.py", line 362, in shadowUpdate
     self._tokenPool[currentToken].start()
 KeyError: '71c853b3-4ee3-49ac-a936-cd62e3e5406e'

After reviewing AWSIoTPythonSDK/core/shadow/deviceShadow.py I’m pretty confused as to how the currentToken that was just added to that dictionary could be missing. Seems like there might be a race-condition or some side-effect internal to the library causing this one.

A second set of eyes would be greatly appreciaed!

UPDATE: This issue was just observed again on 2020-06-23

[rccarper]

The fix is now in this Github repo, as well as in PyPI under version 1.4.9. I’ll close out this ticket, but if you see the issue again, just let us know!

[rccarper]

I’m working on getting the fix through our release process. Once that happens, it’ll be available here.