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nginxamazon-ec2tornadosupervisord
Anirban Roy Das
Anirban Roy Das

Reputation: 262

How many Tornado Instances and How many Nginx Worker Processes

Suppose I am running a web application using Tornado and running them behind Nginx as a Load Balancer. Please tell me the best practices for certain things.

1. If I am running the service in an AWS EC2 instance, then How many NGINX worker processes should I run for a given x number of VCPUs for any particular instance. Lets say I am running on an EC2 instance with 2 VCPUs, then how many worker processes should I run? It would be better if I know the general rule for it. Also, in what conditions should I increase the number of workers as against the general rule?

2. Now after I set my Nginx as load balancer, it boils down to my Tornado Application. So, how many Tornado instances should I run given x number of VCPUs in an EC2 instance? As mentioned in the doc, its good to have 1 instance per processor, but is that the best condition? If yes, then in what scenario, should I look for increasing the number of instances per processor? If not, than what is the best rule?

NOTE : I am running the instances via Supervisord as my process management program.

3. Now if my application does a lot of async calls to MySQL Database and MongooseIM server, all running on the same host, then will the number of Tornado Instances per processor should be changed? If yes, then what is the rule? If not, then what is the best practice?

Upvotes: 1

Views: 405

Answers (1)

Ben Darnell
Ben Darnell

Reputation: 22154

  1. If you are running nginx on a machine by itself, then you should give it as many worker processes as you have CPUs. If you're running it on the same machine as Tornado then you probably want to give it fewer (maybe just one). But it's better to be too high than too low here, so if you're unsure it's fine to use the number of CPUs. You'll want more nginx workers if you're using TLS (especially with stronger security settings) or serving a lot of static files, and fewer if it's just a proxy to Tornado.

  2. One Tornado instance per CPU is the best starting point. You might decrease this number if your application does a lot with threads or if there are other things running on the same machine, and you might increase it if you do any synchronous database/network calls without threads.

  3. As long as your database calls are asynchronous, they do not affect how many Tornado processes you should run.

Upvotes: 2

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