[Bug Report] smarts stuck issue (follow up of #2089)

[Edward11235]

High Level Description

I am using SMARTS 1.2.1 (new verison) to train a model. After training for a long time, SMARTS will always freeze. Below is the error message when I terminate the training:

^CTraceback (most recent call last):
File "train.py", line 748, in
sac(ppo_iters, env, agent, None, current_constraint_function, condition, command)
File "train.py", line 523, in sac
S, A, R, C, log_prob = play_episode(env, policy_nn, constraint_fn)
File "train.py", line 326, in play_episode
env.reset()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/env/hiway_env.py", line 307, in reset
observations = self._smarts.reset(scenario)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/smarts.py", line 454, in reset
return self._reset(scenario, start_time)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/smarts.py", line 489, in _reset
self.teardown()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/smarts.py", line 872, in teardown
self._teardown_providers()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/smarts.py", line 1226, in _teardown_providers
provider.teardown()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/sumo_traffic_simulation.py", line 429, in teardown
self._remove_vehicles()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/sumo_traffic_simulation.py", line 412, in _remove_vehicles
self._traci_conn.vehicle.remove(vehicle_id)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/utils/sumo.py", line 236, in _wrap_traci_method
return method(*args, **kwargs)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/_vehicle.py", line 1474, in remove
self._setCmd(tc.REMOVE, vehID, "b", reason)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/domain.py", line 164, in _setCmd
self._connection._sendCmd(self._cmdSetID, varID, objectID, format, *values)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/connection.py", line 231, in _sendCmd
return self._sendExact()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/connection.py", line 131, in _sendExact
result = self._recvExact()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/connection.py", line 109, in _recvExact
t = self._socket.recv(4 - len(result))
KeyboardInterrupt
Epoch 16: G_avg = 14.83 Gc_avg = 21.91: 3%| | 17/500 [65:09:41<1851:21:23,
Exception ignored in: <function SafeBulletClient.del at 0x7fc47ca98430>
Traceback (most recent call last):
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/utils/pybullet.py", line 52, in del
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/pybullet_utils/bullet_client.py", line 43, in del
TypeError: catching classes that do not inherit from BaseException is not allowed

Version

I used v1.2.1

Steps to reproduce the bug

Running the SMARTS for many episodes for a long time will reproduce the bug.

System info

System info:
Ubuntu 20.04
Python 3.8

Date:
2023-10.1

Error logs and screenshots

^CTraceback (most recent call last):
File "train.py", line 748, in
sac(ppo_iters, env, agent, None, current_constraint_function, condition, command)
File "train.py", line 523, in sac
S, A, R, C, log_prob = play_episode(env, policy_nn, constraint_fn)
File "train.py", line 326, in play_episode
env.reset()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/env/hiway_env.py", line 307, in reset
observations = self._smarts.reset(scenario)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/smarts.py", line 454, in reset
return self._reset(scenario, start_time)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/smarts.py", line 489, in _reset
self.teardown()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/smarts.py", line 872, in teardown
self._teardown_providers()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/smarts.py", line 1226, in _teardown_providers
provider.teardown()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/sumo_traffic_simulation.py", line 429, in teardown
self._remove_vehicles()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/sumo_traffic_simulation.py", line 412, in _remove_vehicles
self._traci_conn.vehicle.remove(vehicle_id)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/utils/sumo.py", line 236, in _wrap_traci_method
return method(*args, **kwargs)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/_vehicle.py", line 1474, in remove
self._setCmd(tc.REMOVE, vehID, "b", reason)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/domain.py", line 164, in _setCmd
self._connection._sendCmd(self._cmdSetID, varID, objectID, format, *values)
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/connection.py", line 231, in _sendCmd
return self._sendExact()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/connection.py", line 131, in _sendExact
result = self._recvExact()
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/sumo/tools/traci/connection.py", line 109, in _recvExact
t = self._socket.recv(4 - len(result))
KeyboardInterrupt
Epoch 16: G_avg = 14.83 Gc_avg = 21.91: 3%| | 17/500 [65:09:41<1851:21:23,
Exception ignored in: <function SafeBulletClient.del at 0x7fc47ca98430>
Traceback (most recent call last):
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/smarts/core/utils/pybullet.py", line 52, in del
File "/home/edward/anaconda3/envs/smarts/lib/python3.8/site-packages/pybullet_utils/bullet_client.py", line 43, in del
TypeError: catching classes that do not inherit from BaseException is not allowed

Impact (If known)

This bug will hinder training large models with SMARTS.