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Type:
Bug
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Resolution: Won't Fix
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: None
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Storage Execution
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ALL
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During asynchronous tests of the Python driver, we occasionally see createIndexes commands hang indefinitely until they reach our 60 second test timeout. These indexes are being created on collections with up to 100 very small, simple documents. The tests that these failures occur on also use the same database and collection, dropping the collection at the start of each for independence. When this drop succeeds, the driver logs that the earlier test's createIndexes command failed with an IndexBuildAborted error.
These failures only occur against authenticated, SSL-enabled clusters running MongoDB 8.0+.
Example logs:
First test
[2025/10/24 07:20:15.421] DEBUG pymongo.serverSelection:logger.py:108 {"message": "Server selection started", "selector": "<function writable_server_selector at 0x7fbdccaddd00>", "operation": "createIndexes", "topologyDescription": "<TopologyDescription id: 68fb85455c4f4a9df6e6059f, topology_type: Sharded, servers: [<ServerDescription ('localhost', 27017) server_type: Mongos, rtt: 0.0010386149606877644>]>", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}}
[2025/10/24 07:20:15.421] DEBUG pymongo.serverSelection:logger.py:108 {"message": "Server selection succeeded", "selector": "<function writable_server_selector at 0x7fbdccaddd00>", "operation": "createIndexes", "topologyDescription": "<TopologyDescription id: 68fb85455c4f4a9df6e6059f, topology_type: Sharded, servers: [<ServerDescription ('localhost', 27017) server_type: Mongos, rtt: 0.0010386149606877644>]>", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}, "serverHost": "localhost", "serverPort": 27017}
[2025/10/24 07:20:15.421] DEBUG pymongo.connection:logger.py:108 {"message": "Connection checkout started", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}, "serverHost": "localhost", "serverPort": 27017}
[2025/10/24 07:20:15.421] DEBUG pymongo.connection:logger.py:108 {"message": "Connection checked out", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}, "serverHost": "localhost", "serverPort": 27017, "driverConnectionId": 14, "durationMS": 0.00017049799998858362}
[2025/10/24 07:20:15.421] DEBUG pymongo.command:logger.py:108 {"message": "Command started", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}, "command": "{\"createIndexes\": \"test\", \"indexes\": [{\"name\": \"num_-1\", \"key\": {\"num\": -1}}], \"lsid\": {\"id\": {\"$binary\": {\"base64\": \"3YaJl0VMRL68j9Kk9D09Eg==\", \"subType\": \"04\"}}}, \"$clusterTime\": {\"clusterTime\": {\"$timestamp\": {\"t\": 1761314827, \"i\": 41}}, \"signature\": {\"hash\": {\"$binary\": {\"base64\": \"NefVupIjjS+iP05oCw6O0Qk+NPs=\", \"subType\": \"00\"}}, \"keyId\": 7564786341519556632}}, \"$db\": \"pymongo_test\"}", "commandName": "createIndexes", "databaseName": "pymongo_test", "requestId": 1280657339, "operationId": 1280657339, "driverConnectionId": 14, "serverConnectionId": 8879, "serverHost": "localhost", "serverPort": 27017}
# This command hangs until the test is terminated by a 60 second timeout limit.
Following test
# Drop command at the start of the test
[2025/10/24 07:20:15.423] DEBUG {"message": "Command started", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}, "command": "{\"drop\": \"test\", \"lsid\": {\"id\": {\"$binary\": {\"base64\": \"+foRcVjARw2Ztw4oQQHAqw==\", \"subType\": \"04\"}}}, \"$clusterTime\": {\"clusterTime\": {\"$timestamp\": {\"t\": 1761314886, \"i\": 1}}, \"signature\": {\"hash\": {\"$binary\": {\"base64\": \"EJtL1kwUtp4pdtC9I2ZbzCgsuhg=\", \"subType\": \"00\"}}, \"keyId\": 7564786341519556632}}, \"$db\": \"pymongo_test\"}", "commandName": "drop", "databaseName": "pymongo_test", "requestId": 1290974871, "operationId": 1290974871, "driverConnectionId": 15, "serverConnectionId": 9093, "serverHost": "localhost", "serverPort": 27017}
# Failed createIndex command started by the previous test
[2025/10/24 07:20:15.423] DEBUG {"message": "Command failed", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}, "durationMS": 60083.457, "failure": "{\"code\": 276, \"codeName\": \"IndexBuildAborted\"}", "commandName": "createIndexes", "databaseName": "pymongo_test", "requestId": 1280657339, "operationId": 1280657339, "driverConnectionId": 14, "serverConnectionId": 8879, "serverHost": "localhost", "serverPort": 27017}
[2025/10/24 07:20:15.423] DEBUG {"message": "Connection checked in", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}, "serverHost": "localhost", "serverPort": 27017, "driverConnectionId": 14}
[2025/10/24 07:20:15.423] DEBUG {"message": "Command succeeded", "clientId": {"$oid": "68fb85455c4f4a9df6e6059f"}, "durationMS": 58.94, "reply": "{\"ok\": 1.0, \"$clusterTime\": {\"clusterTime\": {\"$timestamp\": {\"t\": 1761314887, \"i\": 25}}, \"signature\": {\"hash\": {\"$binary\": {\"base64\": \"p0zbfIZ42ZAGqNitWF74SMTygEg=\", \"subType\": \"00\"}}, \"keyId\": 7564786341519556632}}, \"operationTime\": {\"$timestamp\": {\"t\": 1761314887, \"i\": 25}}}", "commandName": "drop", "databaseName": "pymongo_test", "requestId": 1290974871, "operationId": 1290974871, "driverConnectionId": 15, "serverConnectionId": 9093, "serverHost": "localhost", "serverPort": 27017}
I will attach server logs from these runs once I have them.
- blocks
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- Blocked
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