Comet and node.js - how many simultaneous connections could we expect on an EC2 server?

With a comet server running on node.js - how many simultaneous connections could we expect to get out of an EC2 server?

Anyone done this before and found a reasonable limit?

Our particular application only needs to push data to the clients fairly infrequently, it's more the max simultaneous connections per server that is a worry for us. We're looking at somewhere between 200k - 500k i think, and i'm trying to 开发者_Go百科figure out if comet is going to be workable without a monstrous fleet of servers...

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If you are running Linux, get to know the contents of /proc/sys/net/ipv4

In particular, net.ipv4.netfilter.ip_conntrack_max will let you increase the maximum number of open connections, but when you start plugging in really big numbers you will run into other problems. For instance you might need to reduce orphan_retries because you will statistically be more likely to have orphans. And with really big numbers, it is entirely possible that kernel lookup algorithms will slow down significantly. You need to carefully tune the TCP settings.

If I were in your shoes, I would compare at least two OSes, such as Linux and FreeBSD or OpenSolaris/Illumos.

On FreeBSD you will need to change settings in /boot/loader.conf

On OpenSolaris/Illumos you will need to read the documentation for the ndd command.