[galaxy-dev] Keeping a tool from running multiple times at once

Hi, I am currently working on a workflow with some custom tools, and one of these tools has to create very big temporary files (like 45Go big). As this workflow will be used on a lot of file at the same time, I have to keep it from running more than once or twice at the same time (the other execution would wait in the queue). If I don't, I'm afraid that some memory lack or something could cause all the executions to fail and stop. The problem is : I can't find if it's possible to do that, and if it is, how do I do it. Anyone has an idea please ?