stream {
    limit_conn_zone $binary_remote_addr zone=perip:1m;
    limit_conn_log_level error;

    server {
        ...
        limit_conn perip 1;
    }
}

The function is now called ngx_parse_http_time(), and can be used by
any code to parse HTTP-style date and time.  In particular, it will be
used for OCSP stapling.

For compatibility, a macro to map ngx_http_parse_time() to the new name
provided for a while.

stream {
    server {
        ...
        allow 127.0.0.1;
        deny all;
    }
}

Upstreams with the "zone" directive are kept in shared memory,
with a consistent view of all worker processes.