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Maximum Heat Stack Create Requests

asked 2017-05-22 10:25:29 -0500

Tori gravatar image


As I install my application I execute approx 100 "heat stack create" commands over HTTP api. Each stack creates approx 2-4 VMs. I can see that Openstack accepts all these requests and then (visible on UI) processes the requests in batches and as it completes one adds another to the executing threadpool.

Is there a max number of heat stack create commands I can send towards HEAT? I would assume that if, for example, only one worker thread was available for work that I could still send in a hundred or even a couple of hundred requests, all requests would be accepted via web interface but then downside being it would take a long time for the single worker thread to worker thru all requests.

Question summary

(Assuming sufficient CPU and RAM resources available for my instances)

  1. Is there a max number of requests (stack create) to send in over HTTP interface at any one time
  2. If the HTTP API interface accepts the request it is reasonable to assume that HEAT engine will get to my request eventually (it wont fall over?)
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answered 2017-05-22 18:41:57 -0500

zaneb gravatar image

Each Heat engine has a limited thread pool size (64 from memory), and there is a timeout for replies to RPC calls (2 minutes by default). So if you saturate the thread pool to the point where creating new ones is blocked by more than 2 minutes then things will start to fail. However, this happens synchronously so you will get an error from the REST call.

If Heat accepts your request with 202 Accepted then it is reasonable to assume that it's being acted upon. That doesn't mean the stack operation will succeed - in the cloud you can never be sure of that - but your request shouldn't just get lost after that point.

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Asked: 2017-05-22 10:25:29 -0500

Seen: 114 times

Last updated: May 22 '17