[zeromq-dev] zeromq-dev Digest, Vol 34, Issue 72

[Martin Sustrik]

On 10/14/2010 03:18 PM, Marcelo Cantos wrote:

> On another note, I'm curious about the problems Martin cites regarding
> TCP keepalives and the two-hour timeout. I'm guessing that perhaps this
> is just too long, and that many real-world routers will forget the
> session before then, but I'd be interested in hearing from someone who
> knows what they're talking about. I also note that a two-hour keepalive
> seems to be the minimum /default/, not the minimum value, though this is
> cold comfort on Windows, which doesn't let individual applications
> override the default (I suppose they could change the registry setting,
> if they're desperate).

The problems are:

1. TCP keep-alives is an optional part of TCP spec.
2. The socket options related to keepalives are not in POSIX.
3. Even if there is keepalive on/off option there's no guarantee that 
there's a keepalive interval option -- which locks you to >2 hour default.

We can try to get some of this working, however, my feeling is that it 
won't be easy, if at all possible.

Additionally, even if you get TCP keepalives working, they are 
definitely the nice auto-adjusting heartbeats as those to be seen in SCTP.

Martin