Details
Description
Source data.
A large number (in my case, 500409) of TSVs. The size of each is most often no more than 100 rows.

My actions.
I tried to convert each table to collection using my well-tested Python program.
Error.
After ~15 minutes of running the program an error occurs:
multiprocessing.pool.RemoteTraceback:
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""" |
Traceback (most recent call last):
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File "/home/platon/miniconda3/lib/python3.7/multiprocessing/pool.py", line 121, in worker |
result = (True, func(*args, **kwds))
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File "/home/platon/miniconda3/lib/python3.7/multiprocessing/pool.py", line 44, in mapstar |
return list(map(*args)) |
File "create_db.py", line 211, in create_collection |
'block_compressor=zstd'}}) |
File "/home/platon/miniconda3/lib/python3.7/site-packages/pymongo/database.py", line 408, in create_collection |
with self.__client._tmp_session(session) as s:
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File "/home/platon/miniconda3/lib/python3.7/contextlib.py", line 112, in __enter__ |
return next(self.gen) |
File "/home/platon/miniconda3/lib/python3.7/site-packages/pymongo/mongo_client.py", line 1829, in _tmp_session |
s = self._ensure_session(session)
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File "/home/platon/miniconda3/lib/python3.7/site-packages/pymongo/mongo_client.py", line 1816, in _ensure_session |
return self.__start_session(True, causal_consistency=False) |
File "/home/platon/miniconda3/lib/python3.7/site-packages/pymongo/mongo_client.py", line 1766, in __start_session |
server_session = self._get_server_session()
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File "/home/platon/miniconda3/lib/python3.7/site-packages/pymongo/mongo_client.py", line 1802, in _get_server_session |
return self._topology.get_server_session() |
File "/home/platon/miniconda3/lib/python3.7/site-packages/pymongo/topology.py", line 488, in get_server_session |
None)
|
File "/home/platon/miniconda3/lib/python3.7/site-packages/pymongo/topology.py", line 217, in _select_servers_loop |
(self._error_message(selector), timeout, self.description))
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pymongo.errors.ServerSelectionTimeoutError: localhost:27017: [Errno 111] Connection refused, Timeout: 30s, Topology Description: <TopologyDescription id: 605a9f0f977b5c231ff4873e, topology_type: Single, servers: [<ServerDescription ('localhost', 27017) server_type: Unknown, rtt: None, error=AutoReconnect('localhost:27017: [Errno 111] Connection refused')>]> |
Global MongoDB breakdown.
All further attempts to use MongoDB result in connection errors. Restarting the Mongo process doesn't help.
mongo
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MongoDB shell version v4.4.4 |
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb |
Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused : |
connect@src/mongo/shell/mongo.js:374:17 |
@(connect):2:6 |
exception: connect failed
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exiting with code 1 |

Why do I consider this a MongoDB bug?
The documentation does not describe any limits on the number of collections from the WiredTiger side.