I suspect sometings is going wrong in my webserver (maybe possible DoS attack). In fact I see a lot of such entries:
[Sun Jul 19 10:36:21 2015] [error] [client 141.212.122.18] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /x
[Mon Jul 20 12:19:41 2015] [notice] caught SIGTERM, shutting down
Is it possible to stop them? (fail2ban?)