When removing 23387 documents from the collection which has 250K documents), The BulkOperation was block until the remove is done.
I didn't set the $isolated for this remove operation.

Following is the log regarding the remove operation.

2016-01-17T00:05:05.965-0500 I WRITE [conn1] remove xxx.app query: { app.start_time:

{ $lt: new Date(1453003200000), $lt: new Date(1453003200000) }

} ndeleted:23387 keyUpdates:0 writeConflicts:0 numYields:194 locks:{ Global: { acquireCount:

{ r: 195, w: 195 }

}, Database: { acquireCount:

{ w: 195 }

}, Collection: { acquireCount:

{ w: 195 }

} } 2630ms
2016-01-17T00:05:05.965-0500 I COMMAND [conn1] command xxx.$cmd command: delete { delete: "app", deletes: [ { q: { app.start_time:

{ $lt: new Date(1453003200000), $lt: new Date(1453003200000) }

}, limit: 0 } ], ordered: true, writeConcern: {} } keyUpdates:0 writeConflicts:0 numYields:0 reslen:40 locks:{ Global: { acquireCount:

{ r: 196, w: 196 }

}, Database: { acquireCount:

{ w: 196 }

}, Collection: { acquireCount:

{ w: 196 }

} } 2639ms

Size BulkOperation: 100 operations per BulkOperationBuilder.

Is there a way to make the bulkOperation and remove running concurrently.