[erlang-questions] HTTP requests and the meaning of eaddrinuse
Fri Jan 30 16:45:19 CET 2009
Johnny Billquist wrote:
> Sverker Eriksson wrote:
>> Johnny Billquist wrote:
>>> [...] you will most probably hit the limit of the number of open
>>> file descriptors long before you exhaust all the local port numbers.
>>> By default on on my mac, the max file descriptors is 256 (per
>>> process). There is also a limit on the total number of file
>>> descriptors in the OS. Nowhere near the theoretical limit of 65536
>>> ports in tcp. So that should give you enfile or emfile.
>> The internal TIME_WAIT state of the TCP protocol may cause exhaustion
>> of port numbers even though the file descriptor limit is much lower
>> than 65536. Use the netstat command tool to view lingering
>> connections in TIME_WAIT state.
> True, if the connections aren't closed properly.
Actually, kind of the opposite. The peer that actively closes the
connection by calling close() will cause its "socket" into TIME_WAIT.
It's like a quarantine to avoid late arriving packets of the old
connection from being confused with a new connection using the same
port. A major flaw of TCP if you ask me.
> But yes, that could be it. I wonder if eaddrinuse really is returned
> in that case. [...]
I experienced this some time ago writing a benchmark on Linux. I'm quite
sure it was eaddrinuse that I got when the port numbers where exhausted.
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