how can I temporarily pause other threads using boost::thread?

I have a program with 2 threads (A and B). Is it possible to define a block of code in thread B, which once entered pauses thread A until the block has finished executing?

I am using C++ and the library boost::thread 1.44

EDIT: The problem I had, which prevented me from just using a mutex was that I did not have access to the code in thread A as it's a non-thread-safe library, so I could not control when it accessed my shared resource. I have made some architectural changes to my code and now the resource is no longer shared and the problem is solved.

This is called locking and in boost you would want to use scoped_lock

Check this page out: scoped_lock

Other than the scoped_lock/mutex solution of Grammin you can use a condition variable (perhaps a more common idiom for your problem) or even a barrier.