subrequest cycle cause cpu 100%

[Maxim Dounin]

Hello!

On Mon, Feb 02, 2015 at 10:38:24PM -0500, xinghua_hi wrote:

> hello, 
> 
>         I use error_page = /500.html to show myself 500 page, and for some
> reason, I need ssi include in 500.html, for example:
>        
>         500.html
>   
>          <!--# include virtual="/fastcgi/global" -->
>          <!--# include virtual="/fastcgi/cap" -->
>          <!--# include virtual="/fastcgi/header" -->
> 
>         if fastcgi upstream return 500 response code, it will cause
> subrequest cycle,  a set number of error logs such as "subrequests cycle
> while processing "xxx" while sending response to client". 
> 
>         but if I add "wait" parameter in ssi
> 
>         500.html
>   
>          <!--# include virtual="/fastcgi/global" wait="yes" -->
>          <!--# include virtual="/fastcgi/cap" -->
>          <!--# include virtual="/fastcgi/header" -->
> 
>         I find endless error log such as "subrequest cycle" in error_log,
> and cpu go up to 100%
> 
>         I wonder why wait parameter cause so strange case, thanks

With the "wait" parameter you'll eventually reach the limit as 
well, but it will take longer as there will be no other 
subrequests executed in parallel.

-- 
Maxim Dounin
http://nginx.org/