Unable to close the reader

[yarong-lifemap]

We are trying to implement an auto-update of the database in a background task on a Web Service. However, we cannot find a way to close the reader (even when locked) so that the database file can be replaced with a new one. Any thoughts?

[oschwald]

There is a Dispose method that will call Dispose on the underlying MemoryMappedFile. I don't know if this is sufficient for your use case or not.

On a POSIX system, you should be able to atomically replace the file while the database is open, which is what I would recommend. I don't know offhand if this will work as expected on Windows.

[yarong-lifemap]

Hi @oschwald . Thank you for getting back me so quickly.

I tried dispose and then replacing the file with the new version. However, the file was still locked and the move operation failed. This could also be an Azure / IIS file locking issue.

I'll try to work with multiple files instead for now.

[oschwald]

Another option is to use the memory mode rather than the memory-mapped one. This will load the file into memory rather than mapping the file. You can do this with something like new DatabaseReader(dbFile, FileAccessMode.Memory).

[MaryJJ]

I'm having the same problem... but if the file is loaded into memory, how is the database updated in the service? Do I have to restart my service every time there's an update?
builder.Services.AddSingleton<IGeoIP2Provider>((_) => new DatabaseReader(dbPath, FileAccessMode.Memory));

[horgh]

You would want to create a new DatabaseReader when the file is updated and begin using that new one.

[MaryJJ]

I was able to resolve it by changing the Azure file to NFS