WEBVTT 00:00.290 --> 00:00.830 Hi everyone. 00:00.830 --> 00:02.180 Welcome back to this tutorial. 00:02.180 --> 00:08.810 In this tutorial, we will build a real use case stream pipeline and then compare running it using the 00:08.810 --> 00:11.990 sequential and parallel stream way. 00:13.250 --> 00:18.740 And here I'm going to create another example class called Parallel. 00:19.880 --> 00:20.480 Stream. 00:20.480 --> 00:21.980 Example one. 00:22.700 --> 00:27.320 Let's make this class executable by adding public static void main method. 00:27.410 --> 00:32.990 So in here I'm going to make use of the one of the use case that we coded already. 00:33.020 --> 00:35.750 I'm just going to copy and paste the code from there. 00:35.780 --> 00:39.290 So in here we have this flat map example. 00:39.400 --> 00:45.590 Then I'm going to take this class and run it in parallel and sequential and then compare the result. 00:46.500 --> 00:50.930 So in here, I'm going to have this method here going to be. 00:52.390 --> 00:53.440 Sequential. 00:55.220 --> 00:56.570 Student activities. 00:56.570 --> 00:59.060 And then let's copy the same method. 01:00.420 --> 01:01.740 Going to be parallel. 01:04.640 --> 01:13.280 In order to make the stream, a parallel stream can either call parallel stream directly or. 01:14.730 --> 01:17.920 There is a method called stream dot parallel. 01:17.940 --> 01:24.720 This is going to make you the stream to behave in parallel manner. 01:24.750 --> 01:27.180 What I'm going to do, I'm going to make. 01:28.030 --> 01:28.810 Long. 01:31.460 --> 01:32.390 Runtime. 01:33.400 --> 01:35.680 Are the start time here. 01:35.830 --> 01:38.260 It's going to be system dot. 01:39.430 --> 01:45.580 Runtime milliseconds and this is going to be system dot going to be in time basically. 01:47.020 --> 01:48.250 Runtime milliseconds. 01:48.370 --> 01:51.070 And I'm going to print the duration it took. 01:52.850 --> 01:55.190 Duration to execute the pipeline. 01:57.640 --> 01:58.930 The pipeline in. 02:00.050 --> 02:01.250 Sequential manner. 02:01.250 --> 02:01.900 Right. 02:02.720 --> 02:06.680 That's going to be in time minus the start time. 02:08.910 --> 02:09.670 Be minus. 02:11.760 --> 02:12.200 What is it? 02:12.210 --> 02:13.440 It is complaining. 02:14.610 --> 02:19.200 We have to put it inside the braces so that it will evaluate as an expression. 02:19.760 --> 02:24.000 So I'm going to copy the same thing here and then put it here. 02:24.340 --> 02:27.240 That's the start time over here. 02:29.290 --> 02:29.790 Here we go. 02:29.800 --> 02:31.300 So we have the code reading. 02:31.300 --> 02:33.100 I'm going to change this one as parallel. 02:33.880 --> 02:39.430 Let's explore what is that happening in this use case and then run this program. 02:39.740 --> 02:41.410 So enter the presentation mode. 02:41.500 --> 02:49.060 So here in this example, what is happening is we are getting all the students from the student database 02:49.060 --> 02:55.330 class and then we are calling the stream method and we are mapping the student activities, the student 02:55.330 --> 02:55.900 activities. 02:55.900 --> 03:00.940 If you take a look at it, it is returning a list of student activities. 03:00.940 --> 03:06.880 And then what we are doing is we are performing a flatmap operation and then we are performing a distinct 03:06.940 --> 03:09.700 sorted and collected list. 03:09.940 --> 03:13.090 So these are the different operations that we are performing here. 03:13.130 --> 03:15.130 Let's see how it is performing. 03:15.130 --> 03:21.790 Well, here is it is a sequential stream which is going to perform better or the parallel stream which 03:21.790 --> 03:23.560 is going to perform better. 03:23.770 --> 03:27.370 I'm going to I don't have to put the session because I don't care the care about the result. 03:27.370 --> 03:34.910 I want to check what is the duration it took in order to give you the output. 03:35.760 --> 03:40.140 So I'm going to call sequential print. 03:41.190 --> 03:46.080 Student activities and then parallel print student activities. 03:46.770 --> 03:47.320 There you go. 03:47.340 --> 03:49.710 Now we will run this and check the result. 03:52.540 --> 03:53.350 Run this. 03:56.130 --> 04:01.200 So if we take a look at it, the sequential stream took 97 milliseconds. 04:01.200 --> 04:07.260 But if you take a look at the parallel stream, it just took the 14 milliseconds. 04:07.260 --> 04:12.990 Ideally behind the scenes, it is splitting the data into multiple threads and then processing them 04:12.990 --> 04:15.990 parallelly and give you the result as a output. 04:16.140 --> 04:22.980 So the recommendation here is that always check the performance before we assume parallel is going to 04:22.980 --> 04:24.090 perform better. 04:24.120 --> 04:25.410 That is not the case. 04:25.410 --> 04:29.730 There are certain stream functions which is going to hurt the performance of parallel. 04:29.760 --> 04:32.490 I'll be covering that in the next tutorial. 04:32.760 --> 04:34.980 With this, we came to the end of this tutorial. 04:35.010 --> 04:36.300 Thank you for watching.