ngx_http_sub_module causes requests to hang on a simple match.

[Valentin V. Bartenev]

On Friday 30 June 2017 22:14:55 ptcell wrote:
> I've built with the sub filter enabled and I'm finding it hangs requests if
> there is a match.   It is a very simple substitution/replace.   I've
> resorted to following the request in GDB and the sub module completes and
> calls the next body filter (which in my case appears to be the charset
> module).   I have no other odd modules enabled other than using threads with
> a thread pool size of two (shouldn't matter, right?).  Pausing all the
> threads in GDB shows no obvious place it is hanging.
> 
> If I change the match string to something that doesn't match anything, the
> request works fine.
> 
> Here is my config:
> 
>         location / {
>             root   html;
>             index  index.html index.htm;
>             sub_filter '</title>' 'xxx</title>';
>             sub_filter_once on;
>         }
> 
> nginx -V
> nginx version: nginx/1.7.11
> built by gcc 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 
> configure arguments: --with-http_sub_module --with-debug --with-threads
> --with-cc-opt='-O0 -g'
> 
> Thanks!
> 

This is very old version of nginx.  First of all, you should update up to
the supported version.  There are a bunch of bugs have been fixed.

  wbr, Valentin V. Bartenev