{"id":8132,"date":"2021-06-11T14:44:37","date_gmt":"2021-06-11T18:44:37","guid":{"rendered":"https:\/\/www.redline13.com\/blog\/?p=8132"},"modified":"2021-06-11T14:44:37","modified_gmt":"2021-06-11T18:44:37","slug":"how-many-load-testing-servers","status":"publish","type":"post","link":"https:\/\/www.redline13.com\/blog\/2021\/06\/how-many-load-testing-servers\/","title":{"rendered":"How many load testing servers do you need?"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-8133\" src=\"http:\/\/54.161.25.214\/wp-content\/uploads\/2021\/06\/word-image-70.png\" alt=\"How many load testing servers do you need?\" width=\"400\" height=\"300\" srcset=\"https:\/\/www.redline13.com\/blog\/wp-content\/uploads\/2021\/06\/word-image-70.png 400w, https:\/\/www.redline13.com\/blog\/wp-content\/uploads\/2021\/06\/word-image-70-300x225.png 300w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><\/p>\n<p>You have written your test plan and are ready to run your cloud-based load test with RedLine13, leveraging <a href=\"https:\/\/aws.amazon.com\/what-is-aws\/\">AWS<\/a> resources to easily scale your load profile.\u00a0 However, before you can launch your test, you\u2019ll need to decide on how many <a href=\"https:\/\/aws.amazon.com\/aws\/ec2\">EC2<\/a> load testing servers you will need.\u00a0 In this brief guide, we will discuss the concepts and simple calculations to help you determine that number.<\/p>\n<h3><a id=\"post-8132-_he8vus1qex\"><\/a>EC2 class size<\/h3>\n<p>A prerequisite to scaling your test across multiple load testing servers is determining the instance class and size.\u00a0 In <a href=\"https:\/\/www.redline13.com\/blog\/2019\/05\/best-aws-instance-for-load-testing\/\">another blog post<\/a>, we provide a good starting point for making this determination.\u00a0 <a href=\"https:\/\/www.redline13.com\/blog\/2019\/11\/how-many-vcpus-needed-for-load-testing\/\">This post<\/a> focuses on vCPU which represents an often-encountered constraint. For the purposes of this example, we will use the default server class and size of <span style=\"color: #993300;\"><strong>m3.medium<\/strong><\/span>.<\/p>\n<h3><a id=\"post-8132-_218vzf19nt7k\"><\/a>Scaling up your test<\/h3>\n<p>In determining your ideal EC2 <a href=\"https:\/\/aws.amazon.com\/ec2\/instance-types\/\">class and size<\/a>, likely you have arrived at a load profile for your test.\u00a0 Usually this represents a certain number of requests over a given timeframe.\u00a0 For our hypothetical example let us say that we want to generate 750 requests per second at peak throughput. Let us consider the following profile from a <a href=\"https:\/\/jmeter.apache.org\/\">JMeter<\/a> test plan:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-8134 aligncenter\" src=\"http:\/\/54.161.25.214\/wp-content\/uploads\/2021\/06\/word-image-71.png\" alt=\"JMeter test load profile with about 150 threads\" width=\"787\" height=\"419\" srcset=\"https:\/\/www.redline13.com\/blog\/wp-content\/uploads\/2021\/06\/word-image-71.png 787w, https:\/\/www.redline13.com\/blog\/wp-content\/uploads\/2021\/06\/word-image-71-300x160.png 300w, https:\/\/www.redline13.com\/blog\/wp-content\/uploads\/2021\/06\/word-image-71-768x409.png 768w\" sizes=\"auto, (max-width: 787px) 100vw, 787px\" \/><\/p>\n<p>According to this load profile, our test can be expected to maximally generate 150 simultaneous requests.\u00a0 If each request transaction takes about one second, that equates to approximately 150 requests per second at peak throughput.\u00a0 Since load testing servers run in parallel, our max throughput for our entire load test run from RedLine13 is a function of this maximum throughput times the number of servers we have configured.\u00a0 This of course assumes that we have appropriately selected instance sizes as not to \u201cmax out\u201d their capabilities.<\/p>\n<p>For a test involving five <span style=\"color: #993300;\"><strong>m3.medium<\/strong><\/span> servers, our maximum throughput can be calculated as:<\/p>\n<table>\n<tbody>\n<tr>\n<td style=\"text-align: center;\">\n<pre><span style=\"color: #0000ff;\"><strong>150 requests\/second\/server x 5 servers = 750 requests\/second<\/strong><\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>There are unpredictability factors especially including network response time variability, however we can expect throughput to be reasonably close to this estimate.<\/p>\n<h3><a id=\"post-8132-_v14p2pgr74u9\"><\/a>Another scaling example<\/h3>\n<p>In a slightly different scenario, let us consider this load profile:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-8135 aligncenter\" src=\"http:\/\/54.161.25.214\/wp-content\/uploads\/2021\/06\/word-image-72.png\" alt=\"JMeter test load profile sustaining almost 500 virtual users\" width=\"787\" height=\"419\" srcset=\"https:\/\/www.redline13.com\/blog\/wp-content\/uploads\/2021\/06\/word-image-72.png 787w, https:\/\/www.redline13.com\/blog\/wp-content\/uploads\/2021\/06\/word-image-72-300x160.png 300w, https:\/\/www.redline13.com\/blog\/wp-content\/uploads\/2021\/06\/word-image-72-768x409.png 768w\" sizes=\"auto, (max-width: 787px) 100vw, 787px\" \/><\/p>\n<p>It is similar to the previous except that at peak load we are simulating about 500 simultaneous users.\u00a0 We can also assume the behavior of this test is such that for each thread (<em>i.e.<\/em>, virtual user) we can expect up to three requests to complete each second.\u00a0 This means that our throughput will approach 1,500 requests per second.\u00a0 We also know that these requests happen to be more memory and CPU intensive, therefore we\u2019ll select the <span style=\"color: #993300;\"><strong>m5.4xlarge<\/strong><\/span> instance type.\u00a0 In this case we only want a maximum of 1,500 requests per second to hit our test endpoints, so we will start our test on a single instance.<\/p>\n<h3><a id=\"post-8132-_ilo733o9sgcm\"><\/a>Conclusion<\/h3>\n<p>One of the advantages of load testing in the cloud is that it confers the benefit of almost unlimited scalability \u201con tap\u201d.\u00a0 We can design a single, modular test plan, and then effortlessly achieve massive scale in RedLine13 with just a few mouse clicks.\u00a0 The above examples are intentionally simple to make a point, however the same concepts apply to more complex scenarios.\u00a0 There may be an element of trial and error to ascertain request volumes per unit test, however once this is known your tests can be just as effortlessly scaled to any desired means.<\/p>\n<p>RedLine13 offers a full-featured free trial account, which will allow you to experience all our platform has to offer.\u00a0 <a href=\"https:\/\/www.redline13.com\/Service\">Sign up today<\/a> and see how RedLine13 can work to save time and reduce your load testing costs.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>You have written your test plan and are ready to run your cloud-based load test with RedLine13, leveraging AWS resources to easily scale your load profile.\u00a0 However, before you can launch your test, you\u2019ll need to decide on how many EC2 load testing servers you will need.\u00a0 In this brief guide, we will discuss the concepts and simple calculations to help you determine that number.<a class=\"more-link\" href=\"https:\/\/www.redline13.com\/blog\/2021\/06\/how-many-load-testing-servers\/\">Read More &rarr;<\/a><\/p>\n","protected":false},"author":1,"featured_media":8133,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[88,128,183,283,313,424,450,462],"class_list":{"0":"entry","1":"post","2":"publish","3":"author-user","4":"has-excerpt","5":"post-8132","7":"format-standard","8":"has-post-thumbnail","9":"category-blog","10":"post_tag-aws","11":"post_tag-cloud-load-testing","12":"post_tag-ec2-instance","13":"post_tag-jmeter","14":"post_tag-load-agent","15":"post_tag-redline13","16":"post_tag-scale","17":"post_tag-servers"},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v20.12 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>How many load testing servers do you need? - RedLine13<\/title>\n<meta name=\"description\" content=\"Before launching your test, you\u2019ll need to decide on how many load testing servers you will need. Here we will discuss how to determine that number.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.redline13.com\/blog\/2021\/06\/how-many-load-testing-servers\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How many load testing servers do you need? - RedLine13\" \/>\n<meta property=\"og:description\" content=\"Before launching your test, you\u2019ll need to decide on how many load testing servers you will need. 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