Scenario :Assume a scenario where you send a report to your customer via email and as well as via message(SMS).
In this case you would have 3 threads
1.First thread does all the heavy work of creating report.
2. The second and third thread, Mailer thread and SMS Thread would wait for first thread to finish and once it receives signal,the second and third thread enters simultaneously and get the copy of report and sends to customer via Mail and SMS.
