Is File.Exists an expensive operation?
Re: http://msdn.microsoft.com/en-us/library/system.io.file.exists.aspx
Does anyone know if this is a particularly slow or locking operation which could impact server performance in a large environment?
Answer
In computing, there is actually no such thing as an "expensive operation", unless you consider what it is expensive in relation to.
For instance, in the real world, would $2.000.000 for an object be expensive? What if it is the price of Bahamas? Would it be expensive then? What about for a carton of milk? Is that expensive?
The thing you need to consider is if File.Exists is expensive in terms of the overall operation you intend to do, and whether or not you actually have any alternatives.
If you don't have any alternatives, does it matter if it is expensive or not?
For instance, if you do 1 check if the file exists, and then if it does, you load it in, and spend an hour processing it, then I would assume it would not be considered expensive.
However, if you call it 10 times in a single loop, to figure out if a file exists, and then if it does, just increment a number, then it might be the most expensive single operation you do there.
The only way you can know for sure is to actually measure how long that method call takes, compared to what else you in the same operation.