Hi,

First of all I'm not sure it is a bug and the main point of this post is to find anything that could lead to a more complete diagnostic about the issue:

'Sometimes' (randomly) our server application operations are seriously slowed down, up to 20x slower than they usually are. This occurs about 3 or 4 times per week but leads to stop the production our application is involved in.

This problem appeared 3 weeks ago.

It generally occurs for about 10 minutes to nearly an hour.

We first suspected other reasons (than MongoDB), such as .net WCF client/server communications, but as the problem is really global, including batch operations (such as data files integrations) that have no usage of WCF, we now try to diagnostic what can happen in MongoDB and its C# driver. All functions are concerned by the problem and all functions use MongoDB.

The database itself does not log any long access.

The OpLog keeps about 200 days of operations in hour situation.

There are about 20 to 50 simultaneous connection between our server app and the DB (and no other app has access to it, except few Mongo consoles).

There is no blocking operations at run time (no index creation, for instance), only read/write (insert, save, find, aggregates, etc.).

Concerning the driver usage, we still use MongoClient.GetServer deprecated API, as my little company has only port a part of the application to the newer APIs. So this could be the cause of the issue (or using a mix between legacy and current APIs). But we don't know and I'm in hope some answer here can give us information concerning this point.

I know this description is broad and I apologize about that. I'm of course ready to provide any other information that can help in the diagnostic.

Thanks by advance