Beefy Boxes and Bandwidth Generously Provided by pair Networks
Do you know where your variables are?

Re^2: What's causing the busy wait when using AnyEvent::HTTP

by Anonymous Monk
on Apr 11, 2014 at 11:30 UTC ( #1081948=note: print w/replies, xml ) Need Help??

in reply to Re: What's causing the busy wait when using AnyEvent::HTTP
in thread What's causing the busy wait when using AnyEvent::HTTP

It sounds like you've never used AnyEvent::HTTP before and just scanned the docs to try to answer the question. When http_request is called in void context, it's still easy to cancel a request from within the callback. And you don't understand what load testing is if you suggest limiting concurrent requests to 4.
  • Comment on Re^2: What's causing the busy wait when using AnyEvent::HTTP

Replies are listed 'Best First'.
Re^3: What's causing the busy wait when using AnyEvent::HTTP
by basiliscos (Pilgrim) on Apr 11, 2014 at 15:41 UTC

    Thank you for warm tone of your reply and flattering assumptions about my knowledge.

    Actually, I have written some kind of proxy, which uses AE::HTTP for backend querying. There I've met the limitation HTTP::MAX_PER_HOST = 4

    You request can't be cancelled inside callback, because it is invoked only after http call (successful or unsuccessful).

    I think, I do understand well what is load testing and how AE works. It works in single process CPU thread, that means, that it gets some performance boost only during I/O wait operations via processing or enqueueing other requests. So, might reach the limit of parallel requests much earlier, then you'll get 1000 simultaneously running http requests, due to limitations of the single core CPU. So, perl / AE scheduler might be just overloaded in doing http requests, processing results, and switching between contexts.

    It may be better to gradually rise the number of simultaneous http requests. According to that metrics: AE::HTTPD (written in similar manner as AE::HTTP), serves only about 560 rps (on single CPU core, as I understand). That explains well, that doing 1000 dummy requests, will load your CPU to 100%.

    I can advice you to use ab from apache-tools package for simple load testing, because it is written in C, and aimed for loading.

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1081948]
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others studying the Monastery: (5)
As of 2018-06-23 07:05 GMT
Find Nodes?
    Voting Booth?
    Should cpanminus be part of the standard Perl release?

    Results (125 votes). Check out past polls.