[Twisted-Python] Limiting the number of connections

Adi Roiban adi at roiban.ro
Sun Dec 9 08:04:28 EST 2012

On 9 December 2012 12:31, Miha Valencic <miha.valencic at gmail.com> wrote:
> Hi Adi!
> Let me say upfront, that I'm not seeing any problems as of now. I am
> asking this question out of engineering curiosity mostly and to know
> whta to do if the problem would arose.
> On Sun, Dec 9, 2012 at 10:44 AM, Adi Roiban <adi at roiban.ro> wrote:
>> Hi,
>> Just to summarize:
>> * twisted.protocols.policies.LimitTotalConnectionsFactory is not what
>> you want since the server is still listening on the port?
>> LimitTotalConnectionsFactory is only returning a different protocol to
>> handle the overflow.... closing the new connection is a way to handle
>> the overflow.
> I've never heard of LimitTotalConnectionsFactory before. This
> particular mode of operation is desirable, since the client is
> connected and disconnected. I was aiming more towards a usual approach
> within webservers, where they have a certain amount of tcp workers,
> and size of the waiting queue. That way the client does not get
> disconnected, but waits a little and then gets a result. You know how
> to webserver sometimes times out...
> But, really, thinking about it, this factory is the right after all.
> Akin to "http 550 service unavailable" when the service is not able to
> respond to requests. If I understand the description correctly,
> defining custom protocol that write "unavailable" and closes
> connection, setting this protocol as a overflowProtocol would have the
> exact behaviour I am after.

Yes. You can implement a simple HTTP protocol which always returns 503
or some other code.

>> * After a number of connections the server should stop listening on
>> the port... and then tor re-start listening after the connections are
>> closed?
> No, the server shouldn't accept() the socket after n connections are
> opened(). But see previous paragraph.

I think that we are talking about different "accepts", but
LimitTotalConnectionsFactory should do your job.

Adi Roiban

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