Create a barrier that requires the specified numArrivals to unblock. Use the monotonic system clock as the clock against which the absTime timeouts passed to the timedWait methods are interpreted (see {Supported Clock-Types} in the component-level documentation). The behavior is undefined unless 0 < numArrivals.
Declared in <bslmt_barrier.h>
Barrier(
int numArrivals,
std::chrono::steady_clock const&);