WEBVTT 00:04.950 --> 00:09.780 So guys, now let us understand the concept of overlapping and non overlapping work. 00:10.020 --> 00:18.120 If the thread T1 is doing work, W1 and thread T2 is doing work W2, then the work W1 and W2 is said 00:18.120 --> 00:23.430 to be overlapping if W1 and W2 operates on the same data. 00:23.430 --> 00:24.240 Right. 00:24.480 --> 00:30.990 So let us understand this with the help of an example, let us suppose that W1 represents sorting the 00:30.990 --> 00:38.220 array A in ascending order and W2 represents sorting the same array A in descending order, right? 00:38.220 --> 00:44.820 So you can see that W1 and W2 are the pieces of work which operate on the same data structure, which 00:44.820 --> 00:45.520 is an array. 00:45.520 --> 00:52.260 A So it simply means that the work W1 and W2 highly overlaps with each other. 00:52.260 --> 00:54.810 In fact they overlap 100%. 00:56.300 --> 01:02.630 So since array is a common data structure on which thread, T1 and T2 are operating right. 01:02.780 --> 01:06.620 Therefore, W1 and W2 are overlapping work. 01:07.160 --> 01:12.920 So a general rule is that that if threads access the same data structure of a process, right? 01:12.920 --> 01:18.440 So for example, suppose you have a process and inside this process you have multiple threads. 01:18.440 --> 01:24.650 And if those threads access the same data structure within a process and those data structure could 01:24.650 --> 01:32.510 be some global variable or some data structure in the heap memory, then work done by two threads are 01:32.510 --> 01:34.430 overlapping work, right? 01:35.310 --> 01:40.950 So it is the nature of work, whether the work is overlapping or non overlapping between the threads 01:40.950 --> 01:45.240 which decides whether the thread needs synchronization or not. 01:45.330 --> 01:50.640 Now we will going to discuss in detail the concepts of thread synchronization in other section of this 01:50.640 --> 01:51.480 course. 01:52.970 --> 02:00.950 But here I want to emphasize that the two threads of the same process may or may not need synchronization 02:00.950 --> 02:05.900 depending whether the work assigned to these threads overlaps or not. 02:05.930 --> 02:11.690 We had discussed one process model in which the process represented a TCP server. 02:12.750 --> 02:20.550 That is coming back to this slide and this Dhcp server used to create one separate thread which interact 02:20.550 --> 02:23.450 with the client on behalf of Dhcp server. 02:23.460 --> 02:30.120 So here the work of each of the worker thread is completely isolated and non-overlapping with each other. 02:30.150 --> 02:36.750 Therefore, there is absolutely no need to implement any thread synchronization technique between the 02:36.750 --> 02:38.940 threads t1, T2 and T3. 02:38.970 --> 02:39.660 Right. 02:39.930 --> 02:43.230 So do not just blindly go for thread synchronization. 02:43.230 --> 02:47.790 First, evaluate whether the threads really need thread synchronization or not. 02:47.820 --> 02:55.170 When I say thread synchronization, I mean I literally means all those heavy terms which you must have 02:55.170 --> 03:01.770 heard somewhere like mutexes condition variables, critical section, and so on.