I have a problem with MantaRay JMS: I use a static world map because autodiscovery wouldn’t work in our network. If more than 10 peers are offline, I get an error 4226.
The problem is: Microsoft set a limit of 10 half-open connections with Windows XP SP2. MantaRay tries to contact every peer, and starts a lot of connections. The first 10 connections are Ok, then when the 11th starts, our software must wait for another connection to time out. Any other program trying to access the network on the same PC times out.
Strange thing is: on some PC the connection times out after 1-2 seconds, and the problem has almost no consequences, on some other, we have to wait 10 or 20 seconds. But according to Microsoft, there’s no way to configure the default TCP connect timeout directly, and there are other factors (network switches, routers, VPN…) which could influence that.
I looked at the MantaRay source code, and tried to find a way to set the TCP connect timeout, but MantaRay uses SohetChannels instead of “regular” sockets, and the connect() method has no timeout. Am I missing something?
Problem solved.
I replaced the whole MantaRay with a much simpler JMS provider I wrote: I send a first test message over UDP, a peer is allowed to open a TCP connection only after this first message was received.
This taught me to be careful when using open-source (GPL) software.