expression, godan verb (-u)
be carrying out; be performing
A phrase combining the continuative marker しつつ with 行う, meaning 'while doing' or 'in the process of doing'. Used to describe an ongoing action or process. The two senses differ only in the English glosses (carrying out vs. performing) and are merged here as they represent the same Japanese usage.
彼は調査をしつつ行っている。
He is carrying out the investigation.
会議をしつつ行うのは難しい
It's difficult to hold a meeting while doing other things.