WEBVTT 00:00.410 --> 00:03.960 Hi and welcome back to the Knowledge Portal Video series. 00:03.980 --> 00:10.250 So in this module we'll be talking about one of the load balancer method, which is leased Connect. 00:11.240 --> 00:16.220 So we have already seen on how exactly the round robin works. 00:16.220 --> 00:23.090 So this is one of the other methods which Enginex provides as far as reverse proxy and load balancer 00:23.090 --> 00:23.960 is concerned. 00:24.650 --> 00:30.320 So let me give you an example before we actually go into the leased connect. 00:30.590 --> 00:33.520 So let's assume there are two files. 00:33.840 --> 00:40.760 I'll write big dot php and small dot PHP. 00:45.550 --> 00:54.130 Now big dot PHP basically uses a lot of resources and takes around 20s to execute. 00:54.920 --> 01:02.830 However, small dot PHP is a very fast PHP script and takes around let's assume one second to execute. 01:03.460 --> 01:11.620 So basically the big dot PHP is 20 times slower and more resource consuming than the small dot php. 01:13.700 --> 01:15.660 So here we have two servers. 01:15.680 --> 01:17.930 This is server one and this is server two. 01:19.310 --> 01:21.510 And five client requests. 01:21.530 --> 01:29.720 So let's say the client requests comes to the server one and it is asking for big dot PHP. 01:31.340 --> 01:32.180 I'll just write. 01:35.540 --> 01:43.010 V dot php and there is a second client request b which comes to the server to. 01:45.100 --> 01:47.530 Which ask for small dot php. 01:49.900 --> 01:54.610 Now, basically in order for server one to process this client request. 01:54.640 --> 02:00.910 Server one it will have to take 20s an equivalent amount of resources. 02:01.240 --> 02:09.880 However, for the server two to execute this request, it will take around one second to execute. 02:11.470 --> 02:18.400 Now, if this was a round robin algorithm based load balancer, then the third request, which is request 02:18.430 --> 02:22.450 number C should ideally go to server one. 02:23.110 --> 02:32.290 But in this scenario, server one is already busy trying to execute the big dot php and the server two 02:32.290 --> 02:33.790 is already free now. 02:34.540 --> 02:41.830 So ideally during this time we want the request C to go to server three and not server one. 02:42.370 --> 02:50.540 So during this type of scenarios, running a round robin based algorithm is not very feasible. 02:50.810 --> 02:56.180 So we have another algorithm called as least connect. 02:56.930 --> 03:04.280 So what least connect basically means is forward the request to the server, which has least number 03:04.280 --> 03:05.870 of active connections. 03:06.530 --> 03:11.630 So currently we have B dot PHP, which is already executing. 03:11.630 --> 03:14.840 So there is already an active connection which is going on. 03:15.110 --> 03:21.800 However, for server two there is no active connection because the small dot is already executed. 03:22.430 --> 03:30.620 So for this the C should go to server two. 03:30.830 --> 03:31.340 So. 03:31.340 --> 03:34.100 So the C request has to go to server two. 03:34.670 --> 03:37.790 If it is following the least connect based method. 03:38.180 --> 03:42.230 So let me actually show you on how exactly it works. 03:44.240 --> 03:45.320 So. 03:49.880 --> 03:52.280 So I have two servers in upstream. 03:52.280 --> 03:54.710 This is server one and this is server two. 03:54.740 --> 04:03.860 So let me just refresh the page and here you see it is waiting for PHP script to be executed so it will 04:03.860 --> 04:10.850 take around 20s for this PHP script to be executed and we'll just wait for a while. 04:17.880 --> 04:19.380 And now it is executed. 04:19.380 --> 04:24.030 So it took around 20s and this is small dot PHP. 04:24.960 --> 04:26.280 I'll refresh it. 04:26.850 --> 04:30.390 And here you see it got executed instantaneously. 04:30.660 --> 04:38.970 So what we want is we want to apply the least connect based method of algorithm for our load balancer. 04:39.270 --> 04:41.160 So I've already configured it. 04:41.160 --> 04:44.400 I'll just show you the configuration. 04:46.940 --> 04:47.290 ADC. 04:47.720 --> 04:48.130 Enginex. 04:48.180 --> 04:49.120 Conf.d. 04:49.480 --> 04:50.560 Web conf. 04:53.470 --> 05:00.520 So here what we have mentioned is we have mentioned lease underscore Conn in the upstream directive. 05:00.550 --> 05:07.810 So in the round robin, we don't have to mention anything because it takes round robin as a default. 05:07.840 --> 05:13.870 However, if you want some other load balancing algorithm, then you have to specify the name of algorithm 05:13.870 --> 05:15.070 that you want to choose. 05:15.430 --> 05:18.190 So for this we have choose Lease Connect. 05:21.830 --> 05:24.140 So let's go to the. 05:28.830 --> 05:31.320 Server and let's do apachebench. 05:31.530 --> 05:33.090 So what I'll do is. 05:35.220 --> 05:38.580 I'll do a tail to the engine logs. 05:42.600 --> 05:46.480 So this is server one and this is server two. 05:50.700 --> 05:52.470 So this is row one. 05:52.470 --> 05:57.630 This is server to server one has big PHP, server two has small dot PHP. 05:58.710 --> 06:03.420 Now the naming across both the server is same which is test dot PHP. 06:04.230 --> 06:09.030 So let's keep that in mind and let's run apachebench. 06:10.440 --> 06:11.190 So let's see. 06:11.220 --> 06:19.200 Number of connections limited to 20 concurrent, let's say ten followed by the IP address of the reverse 06:19.200 --> 06:20.130 proxy. 06:24.540 --> 06:27.140 Which is this? 06:28.170 --> 06:29.220 I copy this. 06:30.240 --> 06:31.650 I'll paste it over here. 06:35.900 --> 06:36.590 Oops. 06:39.250 --> 06:40.570 Followed by the code number. 06:41.230 --> 06:41.950 So what? 06:41.980 --> 06:48.970 Basically this will do is it will send ten concurrent requests to the reverse proxy. 06:48.970 --> 06:55.330 So this is the reverse proxy and total number of requests would be 20. 06:55.450 --> 07:03.010 So ideally as we are using least connect the server to which is having small dot php should get the 07:03.010 --> 07:04.960 most number of requests. 07:04.990 --> 07:11.680 However, the server one which is running big dot php should get least number of requests. 07:11.710 --> 07:17.110 So let's run the Apache bench and let's see on how many requests the server each server gets. 07:24.250 --> 07:25.450 About event. 07:27.980 --> 07:29.660 And 20. 07:33.610 --> 07:34.960 Let me figure it out. 07:36.940 --> 07:37.570 Okay. 07:45.010 --> 07:51.310 Apachebench, followed by the total number of requests that we want to send, which is 20 concurrent 07:51.310 --> 07:53.410 requests, will be ten. 07:54.310 --> 08:01.690 The address of the reverse proxy server, which was 52 dot. 08:04.490 --> 08:05.540 6.23. 08:05.540 --> 08:06.350 37.23. 08:06.440 --> 08:16.310 28 6.237.2 28 followed by the optional port number and it seems to be giving some error. 08:17.150 --> 08:18.830 Let's remove the port number. 08:24.990 --> 08:25.470 Okay. 08:27.870 --> 08:33.120 Or you can just put 28 slash and this seems to be working now. 08:33.540 --> 08:34.080 Okay. 08:34.410 --> 08:37.830 So now it is sending 20 number of total requests. 08:37.830 --> 08:42.090 So ideally, let's see on how exactly the logs work. 08:42.720 --> 08:48.540 So this is server two which is running small dot php with the name test dot php. 08:48.750 --> 08:52.650 So this seems to have got the maximum number of requests. 08:52.650 --> 09:02.880 So let's just count one, two, three, four, five, six, seven, eight, nine, ten, 11, 12, 13, 09:02.880 --> 09:04.140 14, 15. 09:04.140 --> 09:12.170 So the server two has got 15 requests and the server one has got only five requests. 09:12.180 --> 09:20.400 So you see with least connect the reverse proxy will send the request to the server which with least 09:20.400 --> 09:22.020 number of active connections. 09:22.020 --> 09:29.380 So this is sometimes useful in a production environment where one of the servers has some very big scripts 09:30.250 --> 09:32.620 while others has the smaller ones. 09:32.770 --> 09:38.020 So this is it about the least connect based algorithm. 09:38.290 --> 09:45.250 I hope this has been informative for you and I'll be posting the scripts, detail the content of the 09:45.250 --> 09:51.780 scripts on the website so you can download it and you can test it on your machines. 09:51.790 --> 09:52.690 So this is it. 09:52.690 --> 09:53.560 About this video. 09:53.560 --> 09:57.100 I hope this has been informative for you and I'd like to thank you for viewing.