WEBVTT 00:05.090 --> 00:12.200 So guys, we were going to discuss thread barrier, which is another data structure for thread synchronization, 00:12.200 --> 00:13.010 right? 00:13.100 --> 00:18.290 So in this section we will going to discuss what thread barrier is, what is its use case, and then 00:18.290 --> 00:21.800 finally we will going to implement this data structure. 00:22.190 --> 00:28.490 So as you can see, picture on the right hand side, it gives you an overall idea regarding what thread 00:28.490 --> 00:30.890 barrier is all about, right? 00:32.300 --> 00:38.180 So thread barrier is a thread synchronization data structure which blocks all the threads at a particular 00:38.180 --> 00:43.880 line of code until some specified number of threads arrive at that barrier point. 00:43.910 --> 00:44.670 Right. 00:44.690 --> 00:51.710 So the definition is quite simple in cases where you must wait for a number of tasks to be completed 00:51.710 --> 00:54.440 before an overall task can proceed. 00:54.470 --> 00:57.250 Barrier synchronization can be used. 00:57.260 --> 01:03.890 So this is a situation where you will use thread barrier like data structure for thread synchronization. 01:04.250 --> 01:10.260 If you want your software or application to wait until all the currently running threads finish their 01:10.260 --> 01:14.610 task and you want your application to continue. 01:14.610 --> 01:20.340 Only when all the running tasks has finished their execution, then in such a situation you must use 01:20.340 --> 01:21.300 thread barrier. 01:21.570 --> 01:27.450 So one practical use case where you can witness the functioning of the thread barrier is that if you 01:27.450 --> 01:34.890 have ever used Iddm, it is called Internet Download Manager, which is a software to download big files 01:34.890 --> 01:36.150 from the internet. 01:36.150 --> 01:36.900 Right. 01:37.690 --> 01:44.620 So this application actually downloads a bigger file in the context of multiple threads where each thread 01:44.620 --> 01:50.530 download a portion of the file independently and when all the threads have completed downloading of 01:50.530 --> 01:55.850 the file, then only the internet download manager reports that the download is success. 01:55.870 --> 01:56.650 Right. 01:56.890 --> 02:01.600 So for example, let us suppose that you have a big file which is present on the internet. 02:01.600 --> 02:11.350 Let us say that this is some video file and let's say the size of this file is 112MB, right? 02:11.440 --> 02:15.730 Now you try to download this video file using internet download manager. 02:15.730 --> 02:23.860 So what this Internet download manager application does is that it divides this file into some independent 02:23.860 --> 02:24.280 parts. 02:24.280 --> 02:31.120 Let us say we divide this file into part one, part two and part three, and then this Internet download 02:31.120 --> 02:39.770 manager launches independent threads which download each independent part of the file in parallel. 02:39.980 --> 02:40.730 Right. 02:40.760 --> 02:47.420 The three threads run concurrently or in parallel on all the available CPUs on the machine. 02:47.420 --> 02:48.230 Right? 02:48.230 --> 02:55.430 So this accelerates the process of downloading a file, an internet download manager as an application, 02:55.430 --> 03:02.210 then aggregate all the pieces together only when all the three threads have actually downloaded their 03:02.210 --> 03:03.920 respective chunk of file. 03:04.100 --> 03:04.880 Right. 03:06.110 --> 03:12.860 So you can see that the internal download manager as an application have to wait until all the threads 03:12.860 --> 03:18.590 have completed their task and when all the threads have completed their task, that is downloading their 03:18.590 --> 03:26.030 respective chunk of a file, then only internet download manager as an application, concatenate or 03:26.030 --> 03:32.090 aggregate all the pieces together to announce to the user that the file downloading has been finished. 03:32.210 --> 03:33.050 Right. 03:33.050 --> 03:37.160 So this is a typical case where thread barrier can be used. 03:37.190 --> 03:43.520 Now I don't know whether internet download manager really use thread barrier or not, but I see it as 03:43.520 --> 03:48.110 a potential use case in which one would like to use thread barrier. 03:48.110 --> 03:48.890 Right.