[db-wg] NRTM replication inefficiencies

On 08/12/2017 15:05, Edward Shryane via db-wg wrote:

> Yes, this is already possible, you can set the SO_KEEPALIVE option
> on the socket.
> 
> However, at least on CentOS7 (Linux), the default is to wait 2 hours
> before sending a keepalive probe, then 9 probes have to fail (each 75s
> apart) before declaring the connection is broken. Changing this default
> behaviour is applied system-wide.

A RIPE NCC internal python application that uses NRTM, does this:

conn = socket.create_connection((self.nrtm_host, self.nrtm_port))

# enable TCP keepalive (but only on Linux - the TCP_KEEPIDLE
# option is not available for other OSes)
# send keepalives after 60s of inactivity
# try 3 probes at 15s intervals before closing the connection

if platform.system() == 'Linux':
    logger.info('enabling TCP keepalive')
    conn.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
    conn.setsockopt(socket.SOL_TCP, socket.TCP_KEEPIDLE, 60)
    conn.setsockopt(socket.SOL_TCP, socket.TCP_KEEPINTVL, 15)
    conn.setsockopt(socket.SOL_TCP, socket.TCP_KEEPCNT, 3)


Regards,
Anand Buddhdev
RIPE NCC