I am connecting to my MongoDB with the official node driver.
I am trying to watch changes, both on a specific collection and a specific document. Both ways are experiencing this error.
My code works perfectly fine most of the time, but sometimes while it's idle it randomly crashes my whole app. I would like to understand why this is happening, and catch the error so it doesn't break my whole app. Unfortunately, it never points to a specific line in my code.
Here is one of my codes (simplified):
let watcher = q.watch({ids: [documentId]}).on("change", (changeEvent) => {
//only listen to update operations
if (changeEvent.operationType !== 'update') return;
console.log('document was updated');
watcher.cursor.close();
});
Which gave me this error:
node:events:371
throw er; // Unhandled 'error' event
^
MongoServerError: Cursor session id (8c01dfe6-6a3e-479c-98ce-243d61ec24e4 - 6tctnoM1KQxUOgLaEIm7HYAvVSF3YGlrCMxn+SswizE=) is not the same as the operation context's session id (none)
at MessageStream.messageHandler (C:\project\node_modules\mongodb\lib\cmap\connection.js:463:30)
at MessageStream.emit (node:events:394:28)
at processIncomingData (C:\project\node_modules\mongodb\lib\cmap\message_stream.js:108:16)
at MessageStream._write (C:\project\node_modules\mongodb\lib\cmap\message_stream.js:28:9)
at writeOrBuffer (node:internal/streams/writable:389:12)
at _write (node:internal/streams/writable:330:10)
at MessageStream.Writable.write (node:internal/streams/writable:334:10)
at TLSSocket.ondata (node:internal/streams/readable:754:22)
at TLSSocket.emit (node:events:394:28)
at addChunk (node:internal/streams/readable:315:12)
Emitted 'error' event on ChangeStream instance at:
at closeWithError (C:\project\node_modules\mongodb\lib\change_stream.js:355:22)
at processError (C:\project\node_modules\mongodb\lib\change_stream.js:445:12)
at Readable.<anonymous> (C:\project\node_modules\mongodb\lib\change_stream.js:364:33)
at Readable.emit (node:events:394:28)
at emitErrorNT (node:internal/streams/destroy:157:8)
at emitErrorCloseNT (node:internal/streams/destroy:122:3)
at processTicksAndRejections (node:internal/process/task_queues:83:21) {
operationTime: Timestamp { low: 1, high: 1629924381, unsigned: true },
ok: 0,
code: 13,
codeName: 'Unauthorized',
'$clusterTime': {
clusterTime: Timestamp { low: 1, high: 1629924381, unsigned: true },
signature: {
hash: Binary {
sub_type: 0,
buffer: Buffer(20) [Uint8Array] [
104, 40, 136, 32, 223, 251,
247, 64, 47, 185, 197, 229,
247, 96, 219, 103, 110, 116,
65, 183
],
position: 20
},
keyId: Long { low: 5, high: 1629063232, unsigned: false }
}
}
}
I also have the other code, which occasionally crashes the same way:
queueCollection.watch([{ $match: { operationType: "insert" }}])
.on("change", (changeEvent) => {
console.debug('document added',currentlyProcessing?'currentlyProcessing':'notCurrentlyProcessing');
if (!currentlyProcessing) processNextQueueItem();
});
If anyone could explain why this error is happening, or how to catch and fix the watcher when it does, that would be great.
I still don't know how to prevent it, but here's how to hack your way around it:
//watches the collection for any inserted documents
function startWatcher (collection) {
console.log('starting watcher');
let watcher = collection.watch([{ $match: { operationType: "insert" }}])
.on("change", (changeEvent) => {
/*whatever you want to do when event is fired*/
})
//changestream connection died (cursor session id is not the same as the operation contexts session id)
.on('error', e => {
console.error('watcher died');
//close current connection
watcher.cursor.close();
//restart new watcher
startWatcher(collection);
});
}
startWatcher(db.collection('collectionname'));