This issue which can be found as;
Still exists in 1.7.12, 1.8 and 1.9
We’ve isolated this between SPDY and (file)caching such as fastcgi_cache
proxy_cache, where exactly is not yet known, should you have this issue
either disable file caching or spdy.
You often need to run debug logging for days to get anything useful,
you have a worker with a de-attached port state then attempt to
This issue is OS independent.
Posted at Nginx Forum: