[whatwg] WebSockets: what to do when there are too many open connections

Simon Pieters simonp at opera.com
Thu May 13 08:05:19 PDT 2010

On Wed, 12 May 2010 20:51:59 +0200, Michael Nordman <michaeln at google.com>  

> On Wed, May 12, 2010 at 4:31 AM, Simon Pieters <simonp at opera.com> wrote:
>> establishing a WebSocket connection:
>> [[
>> Note: There is no limit to the number of established WebSocket  
>> connections
>> a user agent can have with a single remote host. Servers can refuse to
>> connect users with an excessive number of connections, or disconnect
>> resource-hogging users when suffering high load.
>> ]]
>> Still, it seems likely that user agents will want to have limits on the
>> number of established WebSocket connections, whether to a single remote  
>> host
>> or multiple remote hosts, in a single tab or overall. The question is  
>> what
>> should be done when the user agent-defined limit of established  
>> connections
>> has been reached and a page tries to open another WebSocket.
>> I think just waiting for other WebSockets to close is not good. It just
>> means that newly loaded pages don't work.
> Agreed, not good. The intent of the api is to start opening a socket now,
> not at some undefined point in the future after the user has taken some
> undefined action (hey user... please close a tab that has a socket  
> open...
> not particularly user actionable).
>> If there are any WebSockets in CLOSING state, then I think we should  
>> wait
>> until they have closed. Otherwise, I think we should force close the  
>> oldest
>> WebSocket.
> Force closing the oldest is not good. A malicious site could cause all  
> open
> sockets to be closed. Also this would have nasty side effects. Consider a
> memory allocator that just deleted the oldest allocation to make room for
> new allocations, far removed things just start failing on odd ways... no
> thank you.
> An obvious way to handle this condition of "too many sockets are open"  
> is to
> fail to open the new socket with an exception/error which indicates that
> condition.

But then to make the page work the user still has to close a tab that has  
a socket open. But maybe just firing a 'close' event and logging in the  
error console is the best thing to do.

Simon Pieters
Opera Software

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