WEBVTT 00:05.860 --> 00:07.930 So, guys, welcome back. 00:07.930 --> 00:12.400 Now, in this section of the course, we will going to attack on Inter-thread communication. 00:12.400 --> 00:16.990 That is how to set up the communication between the threads of the same process. 00:17.470 --> 00:22.630 So we often feel the need to set up communication between independent threads of the process. 00:22.630 --> 00:27.910 And when I say communication, it simply means exchange of data between the threads. 00:28.390 --> 00:33.280 So a big software system may have built as a multi threaded software, right? 00:33.280 --> 00:38.860 And the threads of this multi threaded software may require exchange data with one another. 00:38.860 --> 00:45.310 So it is quite possible that you build a very big, huge software which is divided into independent 00:45.310 --> 00:48.700 modules, say M1, M2 and M3. 00:48.700 --> 00:55.150 And these modules, M1, M2, M3 are running as separate threads of the same process. 00:56.010 --> 01:02.940 And let us say that these modules, M1, M2 and M3 are nothing, but these are three independent threads 01:02.940 --> 01:03.900 of the same process. 01:03.930 --> 01:05.190 P Right. 01:06.270 --> 01:14.370 Now, it may be required that module M1 may want to send some data to module M2 and M2 may want to send 01:14.370 --> 01:17.610 some data to module M3 and so on. 01:17.610 --> 01:18.360 Right. 01:18.390 --> 01:23.370 This is very normal logistics of a typical big software program, right? 01:23.400 --> 01:29.640 So famous IPC techniques are usually used to set up data exchange between the processes. 01:29.670 --> 01:36.450 So note that there are various IPC techniques which exist today in order to facilitate communication 01:36.450 --> 01:43.620 between the processes and technically, nothing is stopping you from using these IPC techniques to facilitate 01:43.620 --> 01:45.570 communication between the threads. 01:45.600 --> 01:46.350 Right. 01:46.380 --> 01:51.870 So you must have come across the names like sockets, message queues, pipes, shared memory. 01:51.900 --> 01:58.290 These are all the tools that your typical operating system provides to set up the communication between 01:58.290 --> 02:00.240 processes running on the system. 02:00.240 --> 02:00.930 Right. 02:01.870 --> 02:08.140 But when it comes to set up communication between threads, technically nothing is stopping you from 02:08.140 --> 02:12.130 using these techniques to facilitate communication between threads. 02:12.340 --> 02:18.070 You can use any of these techniques for data exchange between the threads of the same process, but 02:18.070 --> 02:20.580 still for inter thread communication. 02:20.590 --> 02:24.370 IPC technique is not the recommended way for data exchange. 02:25.080 --> 02:30.990 In fact, the communication between threads is preferred through callback or function pointers. 02:30.990 --> 02:33.380 And the reason is very clear for this. 02:33.390 --> 02:38.400 The reason is that that the communication through callbacks or function pointers is very fast. 02:38.640 --> 02:40.200 In this type of communication. 02:40.200 --> 02:44.940 There is actually no transfer of data, but there is a transfer of computation. 02:44.940 --> 02:49.290 So we will going to understand this point elaborately in the next lecture video. 02:50.860 --> 02:54.040 In communication through function pointers or callbacks. 02:54.040 --> 02:59.500 There is absolutely no need for the special attention required from the kernel or operating system. 02:59.530 --> 03:04.930 This type of communication is completely and independently supported in the user space. 03:04.960 --> 03:10.660 This does not require any underlying operating system support and therefore no kernel resources need 03:10.660 --> 03:17.410 to be explicitly created to carry out communication between the two threads of the same process using 03:17.410 --> 03:19.260 callbacks or function pointers. 03:19.270 --> 03:24.820 Because at the end of the day, callbacks and function pointer is nothing but it is the invocation of 03:24.820 --> 03:25.630 the function. 03:25.630 --> 03:26.320 Right. 03:27.240 --> 03:34.320 And one function invoke another function completely in the user space without the assistance of underlying 03:34.350 --> 03:36.040 operating system or kernel. 03:36.060 --> 03:36.780 Right. 03:38.600 --> 03:41.450 Unless, of course, your function to is a system call. 03:42.460 --> 03:48.820 So now in the next lecture video, let us focus on this point that communication using callbacks or 03:48.820 --> 03:55.540 function pointers do not involve any actual transfer of data, but in fact it involves the transfer 03:55.540 --> 03:57.100 of computation itself.