Dropped connections with "--syslog" enabled

[mitchellh]

This is extremely strange, but with "--syslog" on, I got a serious amount of dropped connections. Around 50% of curls looked like this:

→ curl -i https://domain.com
curl: (35) Unknown SSL protocol error in connection to domain.com:443 

When I removed the "--syslog" flag, these went away.

Further evidence for this is that we recently switched from Stunnel to Stud. Stunnel had reached a single-core scaling limit so we switched to Stud. Stud immediately handled about 50% of the traffic as Stunnel, which was confusing. When we removed the "--syslog" flag, it went back up to prior numbers.

We run stud as follows:

stud --backend=127.0.0.1,8443 --backlog=500 --ciphers="ALL:!aNULL:!ADH:!eNULL:!MEDIUM:!LOW:!EXP:RC4 RSA: HIGH" --frontend=0.0.0.0,443 --group=stud --keepalive=1800 --quiet --ssl --write-proxy --user=stud --workers=8 /etc/ssl/web.pem

Here is more evidence:

[pkoper]

Looks like you have slow syslog which blocks your stud on /dev/log unix socket. Check disk I/O saturation or look for any other problem with syslog performance like e.g. DNS name resolving. Probably not a stud issue.