Current semaphore construction requires two-way communication, e.g., to
construct a semaphore signaling from rank 0 to rank 1, both rank 0 and
rank 1 need to send a message to each other. This PR fixes an executor
bug that fails to conduct two-way communication for constructing such
one-way semaphores, and instead hangs during the semaphore construction.
In the future, we may need to change the implementation to construct
semaphore via one-way communication.
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Co-authored-by: Changho Hwang <changhohwang@microsoft.com>
