Changes with nginx 1.9.13 29 Mar 2016 *) Change: non-idempotent requests (POST, LOCK, PATCH) are no longer passed to the next server by default if a request has been sent to a backend; the "non_idempotent" parameter of the "proxy_next_upstream" directive explicitly allows retrying such requests. *) Feature: the ngx_http_perl_module can be built dynamically. *) Feature: UDP support in the stream module. *) Feature: the "aio_write" directive. *) Feature: now cache manager monitors number of elements in caches and tries to avoid cache keys zone overflows. *) Bugfix: "task already active" and "second aio post" alerts might appear in logs when using the "sendfile" and "aio" directives with subrequests. *) Bugfix: "zero size buf in output" alerts might appear in logs if caching was used and a client closed a connection prematurely. *) Bugfix: connections with clients might be closed needlessly if caching was used. Thanks to Justin Li. *) Bugfix: nginx might hog CPU if the "sendfile" directive was used on Linux or Solaris and a file being sent was changed during sending. *) Bugfix: connections might hang when using the "sendfile" and "aio threads" directives. *) Bugfix: in the "proxy_pass", "fastcgi_pass", "scgi_pass", and "uwsgi_pass" directives when using variables. Thanks to Piotr Sikora. *) Bugfix: in the ngx_http_sub_filter_module. *) Bugfix: if an error occurred in a cached backend connection, the request was passed to the next server regardless of the proxy_next_upstream directive. *) Bugfix: "CreateFile() failed" errors when creating temporary files on Windows. -- Maxim Dounin http://nginx.org/