C# - Excel Interop (Parallel.For)

Question

Hi All,
I had a Excel Macro which i converted into C#. (Interop)  It has 5 different methods for some calculations for report creation.
2 method out of these are running very slow due  to complex calculation. (10 minutes each for 40 mb data)
After checking these methods, I found that there are few "FOR" loops which takes the time. (It iterate each row in sheet and do some calculation for each cell in row)
After some searching, i found that i can use "parallel.For" loop for enhance performance.
But Thread throws error "Exception from HRESULT: 0x800AC472".  After searching
i found that it because of STA.
Any pointers for better performance with C# to Excel (Interop) parallel programming would be helpful.
Thanks.
Thanks & Regards, Rakesh Parmar

Answer 1

Perhaps you will be also interested in one more optimisation approach. Instead of reading each cell separately, you can transfer a larger range (the entire filled row, or even all of the needed rows) into an array, such as
‘object [,] data = (object [,])someRange.Value2’. Then use this bi-dimensional array. See:
http://www.bing.com/search?q=c%23+increase+excel+performance+range+array.
You can probably also create several Threads manually (if
Parallel.For cannot be used) and control the AppartmentState property. Or process the previous array in parallel with threads or with
Parallel.For.