Python - generator already executing

Drivers & Stacks
1

Hi,
We are using Neo4j driver for python(version 4.2.1).
We have a live system that writes/read from the neo4j cluster all the time, And once in a while we are getting this exception:

Traceback (most recent call last):
  File "main.py", line 85, in on_new_snapshot
    response = customers_list[customer_id]['customer_model_handler_obj']\
  File "/ms_topology_center/../ms_topology_center/customer_model_handler.py", line 130, in on_new_snapshot
    return self.load_last_snapshot_to_graphdb(timestamp=timestamp,
  File "/ms_topology_center/../ms_topology_center/customer_model_handler.py", line 119, in load_last_snapshot_to_graphdb
    self.modeler.create_services('agnostic', region_snapshot_data['created'], account_id, region, timestamp)
  File "/ms_topology_center/../ms_topology_center/modeler.py", line 115, in create_services
    self.graph_db.commit_transaction()
  File "/ms_topology_center/../shared/graph_db.py", line 135, in commit_transaction
    self._transaction.commit()
  File "/usr/local/lib/python3.9/site-packages/neo4j/work/transaction.py", line 134, in commit
    self._connection.fetch_all()
  File "/usr/local/lib/python3.9/site-packages/neo4j/io/_bolt4.py", line 429, in fetch_all
    detail_delta, summary_delta = self.fetch_message()
  File "/usr/local/lib/python3.9/site-packages/neo4j/io/_bolt4.py", line 334, in fetch_message
    details, summary_signature, summary_metadata = next(self.inbox)
  File "/usr/local/lib/python3.9/site-packages/neo4j/io/_common.py", line 79, in __next__
    tag, fields = self.pop()
  File "/usr/local/lib/python3.9/site-packages/neo4j/io/_common.py", line 73, in pop
    return next(self._messages)
ValueError: generator already executing

After this exception appers we are getting several other very strange exceptions:

  • Failed to read from defunct connection IPv4Address(('10.0.201.154', 7687)) (IPv4Address(('10.0.201.154', 7687)))

  • No data

  • Internal server error (Failed to write to closed connection IPv4Address(('10.0.201.154', 7687)) (IPv4Address(('10.0.201.154', 7687))))

File "/ms_topology_center/../shared/graph_db.py", line 135, in commit_transaction
    self._transaction.commit()
  File "/usr/local/lib/python3.9/site-packages/neo4j/work/transaction.py", line 133, in commit
    self._connection.send_all()
  File "/usr/local/lib/python3.9/site-packages/neo4j/io/_bolt4.py", line 296, in send_all
    raise ServiceUnavailable("Failed to write to closed connection {!r} ({!r})".format(
neo4j.exceptions.ServiceUnavailable: Failed to write to closed connection IPv4Address(('10.0.201.154', 7687)) (IPv4Address(('10.0.201.154', 7687)))
  • [Errno 9] Bad file descriptor

After I restart the pod everything back to normal.

Any idea why it's happened to us and how can we avoid this kind of errors?

Thanks ,
Dan Yazerski

2

Hello @dan3,
Did you find any solution for "Failed to read..." & "Failed to write..." errors ?