[Twisted-Python] Problems with long term connections?

Rodrigo Senra rodsenra at gpr.com.br
Thu Feb 15 07:13:07 EST 2007


[ John Pote ]:

|Hi everyone,
|I am putting together a number of servers that will all communicate
|with each other every 5 or 10 minutes via  TCP/IP connections. It
|occured to me that once a connection has been established I might as
|well leave it open permanently. Are there any problems/side effects of
|doing this? 
| Is it better policy to close and re-open the connection every now and
| then?

One advantage of keeping connections opened is to avoid the 3-way
handshake that will take place during connection setup. For a few
number of conenctions I see no immediate disadvantage, but I guess
it all depends on what one means by "few" and the context. 


|Also am I correct in assuming that if a computer at one end of a 
|TCP/IPconnection crashes or otherwise becomes unavailable the twisted 
|program at the other end will only know this when it attempts to send
|a packet to the now crashed computer and, having no reply, gets a
|timeout.

AFAICT, that *is not* a limitation of Twisted. This is simply the fact
that TCP -- while a connection is in silence -- will increment its
timers, since the rx end-point is unaware if nothing is sent or if
the netpath is congested. 


cheers,
Rod Senra

-------------
Rodrigo Senra
GPr Sistemas 
http://www.gpr.com.br




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