For what it's worth, we just merged a pull request that adds connection heartbeating. It could be fun to see if this solves your problem. (In theory it should...)
https://github.com/zeromq/libzmq/pull/1448 On Wed, Jun 24, 2015 at 6:48 PM, Marcin Romaszewicz <[email protected]> wrote: > Yes, you can easily reproduce this by pulling a network cable or shutting > the host down before it can do any sort of TCP connection cleanup. I'm > seeing it in AWS when instances get terminated, because they're given so > little time to respond to TERM that connections aren't cleaned up. > > The iptables approach which Francis mentioned should work as well. > > I'll see if I can come up with a simple example of reproducing this. It > might be even possible to repro this on a single machine simply by > suspending a peer. > > -- Marcin > > On Wed, Jun 24, 2015 at 2:47 AM, Pieter Hintjens <[email protected]> wrote: >> >> Do you think there's any way to reproduce this in the lab, e.g. >> killing a peer before it can shut down TCP properly? >> >> On Tue, Jun 23, 2015 at 10:08 PM, Marcin Romaszewicz <[email protected]> >> wrote: >> > Hi All, >> > >> > I've got an issue with ZMQ_ROUTER sockets which I'm having a hard time >> > working around, and I'd love some advice, but I suspect the answer is >> > that >> > what I want to do isn't possible. >> > >> > Say I have a router socket listening on a port, and I have peers >> > connecting >> > and disconnecting randomly over TCP. These peers have random identities >> > for >> > all intents and purposes. >> > >> > Most of the time, a peer will disconnect "cleanly", meaning the TCP >> > connection is terminated via FIN or RST packets, ZMQ cleans up the file >> > descriptor. >> > >> > However, some of the time, my peer will die silently, effectively due to >> > network outage or power outage or something. >> > >> > In these cases, the router socket keeps the file descriptor around >> > forever. >> > I know that the peer is dead because all my peers heartbeat to each >> > other, >> > and the heartbeats have gone away. I thought that trying to send some >> > data >> > to a dead peer would tear down that connection, since the underlying TCP >> > socket would eventually start erroring, but it doesn't, zmq must be >> > dropping >> > my packet before sending it to the underlying socket. >> > >> > The socket monitor tells me that someone has connected to the router >> > socket >> > on on its bound port with a specific file descriptor, but I've got so >> > many >> > of these coming in that I can't associate a specific file descriptor >> > with a >> > specific peer. >> > >> > TCP keep-alives don't work all that well in raising errors in a dead >> > connection. >> > >> > What I know on the app side due to my heartbeats is that peer XYZ is >> > dead. >> > I'd like to tell the router socket to close the underlying file >> > descriptor. >> > What I know via the monitor is that I have a bunch of file descriptors >> > open, >> > but I can't map them to peers. If I could, I'd just call os.close() on >> > that >> > file descriptor and hopefully ZMQ would handle this gracefully. >> > >> > Eventually, in a few hours of uptime, my process hits the os file >> > descriptor >> > limit, and stops receiving new connections on the zeromq level. I can >> > have >> > the process quit when it detects this, but that forces all the >> > functioning >> > peers to reconnect and re-do some work, so I'd like to avoid it. >> > >> > I scanned the previous discussions about it, and there has been mention >> > of >> > exposing this somehow, but I don't see anything along these lines in the >> > latest API. (looking at 4.1.2 release). >> > >> > Any suggestions on how I could work around this? >> > >> > I'm thinking of extending the socket monitor to have a new event type, >> > like >> > ZMQ_PEER_CONNECT/DISCONNECT which passes back the peer ID and file >> > descriptor, but I've not gone through the zmq code enough yet to know >> > how >> > much work this would be. >> > >> > Thanks in advance, >> > -- Marcin >> > >> > >> > >> > _______________________________________________ >> > zeromq-dev mailing list >> > [email protected] >> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev >> > >> _______________________________________________ >> zeromq-dev mailing list >> [email protected] >> http://lists.zeromq.org/mailman/listinfo/zeromq-dev > > > > _______________________________________________ > zeromq-dev mailing list > [email protected] > http://lists.zeromq.org/mailman/listinfo/zeromq-dev > _______________________________________________ zeromq-dev mailing list [email protected] http://lists.zeromq.org/mailman/listinfo/zeromq-dev
