Tencent’s Kings of Glory is one of the top grossing games worldwide in 2017 so far. Over the last 12 months, we have seen a number of team-based multiplayer games hit the market as companies look to replicate the success of Tencent’s (known as in the west) which is one of the top grossing games in the world in 2017. King of Glory Arena of Valor Even our partners has recently dipped into the genre with , which offers a different take on the traditional MOBA ( ) formula. Supercell Brawl Stars Multiplayer-Online-Battle-Arena Supercell’s Brawl Stars offers a different experience to the traditional MOBA format, it is built with mobile in mind and prefers simple controls & maps, as well as shorter matches. Here at , we have been exploring ideas for a competitive multiplayer game, which is still in prototype so I can’t talk about it here. However, I can talk about how we use AWS Lambda to load test our homegrown networking stack. Space Ape Games Why Lambda? The traditional approach of using EC2 servers to drive the load testing has several problems: : any sizeable load test would require many EC2 instances to generate the desired load. Since it costs you to keep these EC2 instances around, it’s likely that you’ll only spawn them when you need to run a load test. Which means there’s a 10–15 mins lead time before every test just to wait for the EC2 instances to be ready. slow to start : when the load test is short-lived (say, < 1 hour) you can incur a lot of wastage because EC2 instances are billed by the hour with a minimum charge for one hour ( is coming to non-Windows EC2 instances in Oct 2017, which would address this problem). wastage per-second billing : to update the load test code itself (perhaps to introduce new behaviours to bot players), you need to invest in the infrastructure for updating the load test code on the running EC2 instances. Whilst this doesn’t have to be difficult, after all, you probably already have a similar infrastructure in place for your game servers. Nonetheless, it’s yet another distraction that I would happily avoid. hard to deploy updates AWS Lambda addresses all of these problems. It does introduce its own limitations — especially the 5 min execution time limit. However, as I have before, you can work around this limit by writing your Lambda function as a recursive function and taking advantage of container reuse to persist local state from one invocation to the next. written I’m a big fan of the work the Nordstrom guys have done with the project. Unfortunately we’re not able to use it here because the game (the client app written in Unity3D) converses with the multiplayer server in a custom protocol via TCP, and in the future that conversation would happen over Reliable UDP too. serverless-artillery _Combine serverless with artillery and you get serverless-artillery for instant, cheap, and easy performance testing at…_github.com Nordstrom/serverless-artillery Akka Our multiplayer server is written in Scala with the framework. To help us optimize our implementation we collect lots of metrics about the Akka system as well as the JVM — GC, heap, CPU usage, memory usage, etc. Akka The framework is a big help here, it made quick work of getting us insight into the running of the Akka system — no. of actors, no. of messages, how much time a message spends waiting in the mailbox, how much time we spend processing each message, etc. Kamon All of these data points are sent to , via . Wavefront Telegraf We collect lots of metrics about the Akka system and the JVM. We also have a standalone Akka-based load test client that can simulate many concurrent players. Each player is modelled as an , which simulates the behaviour of the Unity3D game client during a match: actor find a multiplayer match connect to the multiplayer server and authenticate itself play a 4 minute match, sending inputs at 15 times a second report “client side” telemetries so we can collect the RTT ( ) as experienced by the client, and use these telemetries as a qualitative measure for our networking stack Round-Trip Time In the load test client, we use the algorithm to minimise the memory footprint required to track the RTTs during a match. This allows us to simulate more concurrent players in a memory-constrained environment such as a Lambda function. t-digest AWS Lambda + Akka We can run the load test client inside a Java8 Lambda function and simulate 100 players per invocation. To simulate concurrent players, we can create concurrent executions of the function via SNS (which has an policy). X X/100 one-invocation-per-message To create a gradual ramp up in load, a recursive function will gradually dial up the no. of current executions by publishing more messages into SNS, each triggering a new recursive load test client function. Orchestrator A function that is triggered by API Gateway allows us to easily kick off a load test from a Jenkins pipeline. LoadTest Using the pattern (see for detail), we can track the progress of all the concurrent load test client functions. When they have all finished simulating their matches, we’ll kick off the function. push-pull this post Aggregator The function would collect the RTT metrics published by the load test clients and produce a report detailing the various percentile RTTs. Aggregator {"loadTestId": "62db5790-da53-4b49-b673-0f60e891252a","status": "completed","successful": 43,"failed": 2,"metrics": {"client-interval": {"count": 7430209,"min": 0,"max": 140,"percentile80": 70.000000193967,"percentile90": 70.00001559848,"percentile99": 71.000000496589,"percentile99point9": 80.000690623146,"percentile99point99": 86.123610689566},"RTT": {"count": 744339,"min": 70,"max": 320,"percentile80": 134.94761466541,"percentile90": 142.64720935496,"percentile99": 155.30086042676,"percentile99point9": 164.46137375328,"percentile99point99": 175.90215268392}}} Like what you’re reading but want more help? I’m happy to offer my services as an and help you with your serverless project — architecture reviews, code reviews, building proof-of-concepts, or offer advice on leading practices and tools. independent consultant I’m based in and currently the only UK-based . I have nearly of with running production workloads in AWS at scale. I operate predominantly in the UK but I’m open to travelling for engagements that are longer than a week. To see how we might be able to work together, tell me more about the problems you are trying to solve . London, UK AWS Serverless Hero 10 years experience here I can also run an to help you get with your serverless architecture. You can find out more about the two-day workshop , which takes you from the basics of AWS Lambda all the way through to common operational patterns for log aggregation, distribution tracing and security best practices. in-house workshops production-ready here If you prefer to study at your own pace, then you can also find all the same content of the workshop as a I have produced for Manning. We will cover topics including: video course authentication authorization with API Gateway Cognito & & testing running functions locally & CI/CD log aggregation monitoring best practices distributed tracing with X-Ray tracking correlation IDs performance cost optimization & error handling config management canary deployment VPC security leading practices for Lambda, Kinesis, and API Gateway You can also get the face price with the code . Hur­ry though, this dis­count is only avail­able while we’re in Manning’s Ear­ly Access Pro­gram (MEAP). 40% off ytcui

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