C# - Making sync function to async

Question

Hi,

I am just wondering if below code changes (New Code) make any difference in performance with respective to calling cosmos from a web api

Old Code:

public string GetDocs()
{
return JsonConvert.SerializeObject(CreateDocumentQuery().ToList());
}

New Code:

public Task<string> GetDocs()
{
return JsonConvert.SerializeObject(CreateDocumentQuery().ToList());
}

So adding Task<string> makes the method async or will it make any difference?

please help in understanding this, Thanks in advance.

Regards,
Sravan kumar

Answer 1

Old Code:

public string GetDocs()
{
return JsonConvert.SerializeObject(CreateDocumentQuery().ToList());
}

New Code (properly written - while async would work, it gives compile warnings):

public Task<string> GetDocs()
{
return Task.ResultFrom(JsonConvert.SerializeObject(CreateDocumentQuery().ToList());
}

this code converts sync code to callable as async (returns a Task), but does not make the code actually async. You are just adding the async calling overhead.

you need to use cosmos db async access methods if you want to improve performance. if this is for asp.net core, you should always use the async versions and never use the sync methods (ToList(), First(), etc).