ngx_http_sub_module causes requests to hang on a simple match.

Peter Booth peter_booth at
Mon Jul 3 15:01:15 UTC 2017

What happens if you simplify the match string to only contain characters? Something like 

>> sub_filter 'xxx' 'yyy';

Can it ever do a substitute?

Sent from my iPad

> On Jul 2, 2017, at 8:26 AM, Valentin V. Bartenev <vbart at> wrote:
>> 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
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