id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,difficulty 1450,TCP connections can cause process to hang,sjamaan,,"As reported by Jim Ursetto, his Spiffy server (which is running on localhost behind a NGINX proxy) will stop responding at some point. It is currently not 100% clear when exactly this happens. As Jim says: > I believe I’ve tracked down the problem, although not the solution yet. It seems the file descriptor table is filled up with half open sockets. lsof shows: > > … > chickadee 13361 jim 1019u sock 0,7 0t0 2365037 can't identify protocol > chickadee 13361 jim 1020u sock 0,7 0t0 2366414 can't identify protocol > chickadee 13361 jim 1021u sock 0,7 0t0 2368047 can't identify protocol > chickadee 13361 jim 1022u sock 0,7 0t0 2368343 can't identify protocol > > And this message on Linux seems to occur when sockets are half-open (or half-closed, if you are a pessimist). And later: > my hunch is that this happens when the connecting side hangs up while we are still sending. Which is probably obvious from my previous description of the problem. I was going to start attacking it by inserting strategic sleeps at various locations to try and manually trigger it, although you probably have a better way. Obviously you do appear to catch all errors in spiffy, so I’m not sure if one of those error handlers is neglecting to close a socket, if the socket close fails and isn’t reported, or if this is a deeper bug inside the tcp unit. I hear faint echoes of #340...",defect,new,major,someday,core libraries,4.13.0,,"tcp, spiffy, sockets, hang, scheduler",Jim Ursetto felix winkelmann Mario Domenech Goulart,hard