[squid-dev] [PATCH] Fixed Write.cc:41 "!ccb->active()" assertion

[Amos Jeffries]

On 15/11/2016 7:03 a.m., Christos Tsantilas wrote:
> The following sequence of events triggers this assertion:
>   - The server sends an 1xx control message.
>   - http.cc schedules ConnStateData::sendControlMsg call.
>   - Before sendControlMsg is fired, http.cc detects an error (e.g., I/O
> error or timeout) and starts writing the reply to the user.
>   - The ConnStateData::sendControlMsg is fired, starts writing 1xx, and
> hits the "no concurrent writes" assertion.
> 
> We could only reproduce this sequence in the lab after changing Squid
> code to trigger a timeout at the right moment, but the sequence looks
> plausible. Other event sequences might result in the same outcome.
> 
> To avoid concurrent writes, Squid now drops the control message if
> Http::One::Server detects that a reply is already being written. Also,
> ConnStateData delays reply writing until a pending control message write
> has been completed.
> 
> 
> There is strong possibility that the bug fixing this patch is a variant
> of the bug4174:
>   http://bugs.squid-cache.org/show_bug.cgi?id=4174
> However we are getting different backtrace.
> 
> 
> This is a Measurement Factory project.
> 

+1. Looks okay.

Amos