Same UF used simulatenously

I created a UF (really a series of UF's) that perform a process in the SAP item Master data. This is process is triggered by multiple different people. 

I am worried about what will happen if more than one person tries to initiate this UF by using the function button at the same time.

The UF takes about 10 seconds to run all the way through too, so what happens if someone, for example, submits a new run 5 seconds into an existing one? Is there any way to freeze the function button from being used if someone else is running the associated UF?