MongoDB / C# Driver and Memory Issue

Question

I'm using MongoDB 1.8.2 (Debian) and mongo-csharp-driver 1.1.0.4184 (IIS 7.5/.Net 4.0 x64).

Multiple items are inserted every second in a existing collection with ~ 3,000,000 objects (~ 1.9 GB).
The WebServer memory is increasing by ~ 1 MB after every insert -> which leads very fast to > 2 GB memory usage.
The memory is never released anymore and only an application pool recycle can free the memory.

Any ideas?

MongoServer server = MongoServer.Create(mongoDBConnectionString);
MongoDatabase database = server.GetDatabase(dbName);                

MongoCollection resultCollection = database.GetCollection("Result");
resultCollection.Insert(result);

result looks like

private class Result
{
    public ObjectId _id { get; set; }            
    public DateTime Timestamp { get; set; }
    public int Location { get; set; }            
    public string Content { get; set; }
}

UPDATE:

My problem is not the insert, it's the select - sorry weird codebase to investigate ;-)

I reproduced it with this sample Code:

Console.WriteLine("Start - " + GC.GetTotalMemory(false).ToString("#,###,##0") + " Bytes");

for (int i = 0; i < 10; i++)
{
    MongoServer server = MongoServer.Create(mongoDBConnectionString);
    MongoDatabase database = server.GetDatabase(dbName);

    MongoCollection resultCollection = database.GetCollection("Result");
    var query = Query.And ( Query.EQ("Location", 1), Query.GTE("Timestamp", DateTime.Now.AddDays(-90)) );

    MongoCursor cursor = resultCollection.FindAs(query);

    foreach (Result result in cursor)
    {
        // NOOP
    }

    Console.WriteLine(i + " - " + GC.GetTotalMemory(false).ToString("#,###,##0") + " Bytes");
}

Output from a .Net 4.0 Console Application with 10.000 results in the cursor:

Start - 193.060 Bytes
0 - 12.736.588 Bytes
1 - 24.331.600 Bytes
2 - 16.180.484 Bytes
3 - 13.223.036 Bytes
4 - 30.974.892 Bytes
5 - 13.335.236 Bytes
6 - 13.439.448 Bytes
7 - 13.942.436 Bytes
8 - 14.026.108 Bytes
9 - 14.113.352 Bytes

Output from a .Net 4.0 Web Application with the same 10.000 results in the cursor:

Start - 5.258.376 Bytes 
0 - 20.677.816 Bytes
1 - 29.893.880 Bytes
2 - 43.783.016 Bytes
3 - 20.921.280 Bytes
4 - 34.814.088 Bytes
5 - 48.698.704 Bytes
6 - 62.576.480 Bytes
7 - 76.453.728 Bytes
8 - 90.347.360 Bytes
9 - 104.232.800 Bytes

RESULT:

Bug was reported to 10gen and they will fix it in version >= 1.4 (they are working currently on 1.2)!!!

MongoDB / C# Driver and Memory Issue

1 Answers