Re: url-retrieve may cause hang

[Kim F. Storm]

Magnus Henoch <address@hidden> writes:

> David Reitter <address@hidden> writes:
>
>> url-retrieve may cause Emacs to hang for around 3 minutes when the
>> firewall is configured to delay packets. This is unwanted behavior,
>> as url-retrieve claims to work asynchronously.
>>
>> Example:
>>
>> Configure firewall to delay (rather than deny) packets:
>>
>> sudo ipfw add 1 pipe 7 tcp from any to any 80
>>
>> (url-retrieve  "http://www.google.com"; 'print)
>> % or use url-http for this
>>
>> -> Hang until time-out (several minutes).
>
> The problem is in url-open-stream in url-gw.el.  The URL library uses
> open-network-stream, which blocks until the connection is established
> (or times out, in this case).  url-retrieve is indeed asynchronous
> when the connection is established.
>
> It should use make-network-process with appropriate arguments, and set
> up sentinels and such, which is the first thing I intend to do after
> the release, as it might be tricky to get it right.  Or should I
> change my plan and do it now?

I doubt it is very tricky to do.  

You should check with (featurep 'make-network-process '(:nowait t))
to see if non-blocking connect is possible, and fallback to
the current blocking code if not.

Try making the change -- then we can look at the patches and judge
whether it is ok to install before the release (if it hasn't happened
before).

-- 
Kim F. Storm <address@hidden> http://www.cua.dk