# Will NGX\_AGAIN kill performance?

**URL:** <https://www.ruby-forum.com/t/will-ngx-again-kill-performance/212180>\
**Category:** NGINX\
**Created:** [September 24, 2011, 4:48pm UTC](https://www.ruby-forum.com/t/will-ngx-again-kill-performance/212180 "2011-09-24T16:48:40Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\
**Post date:** [September 24, 2011, 4:48pm UTC](https://www.ruby-forum.com/t/will-ngx-again-kill-performance/212180/1 "2011-09-24T16:48:40Z")

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hi,

i currently dev a module which makes multi subrequest sequently in the  
access phase handler, via returning NGX\_AGAIN.

my question is, will this kill the performance? and how far could it go  
in  
killing performance.

thx!

Abioy

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**Author:** ![Abioy\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/71e660/32.png) [@Abioy\_S](https://www.ruby-forum.com/u/Abioy_S)\
**Post date:** [September 25, 2011, 9:23am UTC](https://www.ruby-forum.com/t/will-ngx-again-kill-performance/212180/2 "2011-09-25T09:23:56Z")

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On Sat, Sep 24, 2011 at 10:47 PM, Abioy S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> hi,
> 
> i currently dev a module which makes multi subrequest sequently in the  
> access phase handler, via returning NGX\_AGAIN.
> 
> my question is, will this kill the performance? and how far could it go in  
> killing performance.

NGX\_AGAIN is usually for non-blocking I/O operations, it’s key for  
good performance under high concurrency levels.

Regards,  
-agentzh

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**Author:** ![Abioy\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/71e660/32.png) [@Abioy\_S](https://www.ruby-forum.com/u/Abioy_S)\
**Post date:** [September 26, 2011, 4:59am UTC](https://www.ruby-forum.com/t/will-ngx-again-kill-performance/212180/3 "2011-09-26T04:59:45Z")

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hi,

> NGX\_AGAIN is usually for non-blocking I/O operations, it’s key for  
> good performance under high concurrency level  
> in fact, that’s what i’m doing. but i also doubt if the main request  
> wake up  
> every time an event arrived(made by not only subrequest), will it spent  
> most  
> of the time doing sth useless?

thx

Abioy