It is currently used from master process on abnormal worker termination to
unlock accept mutex (unlocking of accept mutex was broken in 1.0.2). It is
expected to be used in the future to unlock other mutexes as well.
Shared mutex code was rewritten to make this possible in a safe way, i.e.
with a check if lock was actually held by the exited process. We again use
pid to lock mutex, and use separate atomic variable for a count of processes
waiting in sem_wait().
*) Change: the "variables_hash_max_size" and
"variables_hash_bucket_size" directives.
*) Feature: the $body_bytes_sent variable can be used not only in the
"log_format" directive.
*) Feature: the $ssl_protocol and $ssl_cipher variables.
*) Feature: the cache line size detection for widespread CPUs at start
time.
*) Feature: now the "accept_mutex" directive is supported using
fcntl(2) on platforms different from i386, amd64, sparc64, and ppc.
*) Feature: the "lock_file" directive and the --with-lock-path=PATH
autoconfiguration directive.
*) Bugfix: if the HTTPS protocol was used in the "proxy_pass" directive
then the requests with the body was not transferred.
