This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I believe, when multiple threads are involve, all of them will enter the run method and proceed upto the call to the synchronized receiveFile method. However, the first thread to enter the receiveFile method will block the rest of the threads until completion.