SpreadsheetGear 2009 includes interruptible background calculation which is enabled by default, making it responsive even when calculating large and complex models. SpreadsheetGear 2009 also supports applications which respond to events by updating workbook sets from a background thread.
Efficiently supporting interruptible background calculation and changes in response to background events requires the use of GetLock and ReleaseLock anytime a workbook set will be accessed, to ensure that multiple threads are not accessing the workbook set at the same time.
It is important to note that background calculation will never be initiated unless GetLock and ReleaseLock are used. The WorkbookView Windows Forms control calls GetLock and ReleaseLock as needed, so applications which use the WorkbookView control must also use GetLock and ReleaseLock as needed unless background calculation is disabled. In applications which create their own workbook set, such as in ASP.NET applications, it is typical for only one thread to access a workbook set, and background calculation may or may not be beneficial.
See GetLock and ReleaseLock for more information.