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Type:
Bug
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Resolution: Fixed
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Priority:
Unknown
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Affects Version/s: None
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Component/s: None
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None
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Fully Compatible
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Dotnet Drivers
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Not Needed
Summary
An InvalidOperationException occurs due to a null casting issue in MongoDB C# driver when handling heartbeat events. This leads to a TimeoutException and client disconnection from the server.
Please provide the version of the driver. If applicable, please provide the MongoDB server version and topology (standalone, replica set, or sharded cluster).
- Driver Version: 2.25.0
How to Reproduce
- Configure MongoDB client settings with heartbeat event subscriptions as shown in the code example below.
- Run the code and wait for the heartbeat events to be triggered.
var mongoClientSettings = MongoClientSettings.FromConnectionString("mongodb://localhost:27017"); mongoClientSettings.ClusterConfigurator += clusterBuilder => { clusterBuilder.Subscribe<ServerHeartbeatStartedEvent>( ev => Console.WriteLine($"Server {0} heartbeat started (connId: { ev.ConnectionId.ServerValue})") ); clusterBuilder.Subscribe<ServerHeartbeatSucceededEvent>( ev => Console.WriteLine($"Server {0} heartbeat succeeded (connId: { ev.ConnectionId.ServerValue})") ); clusterBuilder.Subscribe<ServerHeartbeatFailedEvent>( ev => Console.WriteLine($"Server {0} heartbeat failed (connId: { ev.ConnectionId.ServerValue})") ); }; var mongoClient = new MongoClient(mongoClientSettings); var db = mongoClient.GetDatabase(Guid.NewGuid().ToString().Substring(0, 8)); await db.CreateCollectionAsync("test");
Exception
System.TimeoutException : A timeout occurred after 30000ms selecting a server using CompositeServerSelector{ Selectors = WritableServerSelector, LatencyLimitingServerSelector{ AllowedLatencyRange = 00:00:00.0150000 }, OperationsCountServerSelector }. Client view of cluster state is { ClusterId : "2", Type : "Unknown", State : "Disconnected", Servers : [{ ServerId: "{ ClusterId : 2, EndPoint : "Unspecified/localhost:27017" }", EndPoint: "Unspecified/localhost:27017", ReasonChanged: "Heartbeat", State: "Disconnected", ServerVersion: , TopologyVersion: , Type: "Unknown", HeartbeatException: "System.InvalidOperationException: Nullable object must have a value.
at MongoDB.Driver.Core.Connections.ConnectionId.get_ServerValue()
Additional Background
The exception is triggered by an attempt to access ConnectionId.ServerValue, where ServerValue is null. The issue appears to be caused by changes introduced in CSHARP-4417: ConnectionId should use longs for LocalValue and ServerValue to match 64-bit integer connectionId returned from the server
namespace MongoDB.Driver.Core.Connections
{
public sealed class ConnectionId : IEquatable<ConnectionId>
{
private readonly long? _serverValue;
[Obsolete("Use LongServerValue instead.")]
public int? ServerValue
{
get { return (int)_serverValue; }
}
}
}