question: protected Map < URI , ExecutionWindow > waitForActiveWindows ( ) throws InterruptedException { Map < URI , ExecutionWindow > windows = Maps . newHashMap ( ) ; while ( windows . isEmpty ( ) ) { lock . lock ( ) ; try { if ( activeWindows . isEmpty ( ) && enableInfiniteExecutionWindow == false ) { hasActiveWindows . await ( ) ; } windows . putAll ( activeWindows ) ; if ( enableInfiniteExecutionWindow == true ) { return windows ; } } finally { lock . unlock ( ) ; } } return windows ; }
target:  Waits for active windows to become available. This will not return until at least one window is active.