[erlang-questions] : file:open's delayed_write behavior does not correspond to docs.

Raimo Niskanen <>
Wed Feb 21 09:10:27 CET 2007


I will put it on my ToDo list and we'll have to see when it gets
scheduled in...



On Tue, Feb 20, 2007 at 05:24:06PM -0800,  wrote:
> Thanks for checking this.  Is this bug something that can be fixed for
> R11B-4?
> 
> Derek
> 
> Raimo Niskanen writes:
> > I can confirm your reported behaviour, on Solaris 8 using 
> > truss to see the system calls.
> > 
> > It seems to be a bug that nobody noticed. It appears that after
> > the set time the delayed write is transferred to the file drivers
> > todo queue, but the queue is not checked until next event,
> > which is the next write.
> > 
> > 
> > 
> > On Mon, Feb 19, 2007 at 10:35:43PM -0800,  wrote:
> > > I have opened a port using
> > > 
> > >   file:open("/path/to/file", [append, raw, delayed_write])
> > > 
> > > and the process holding open the port receives messages, converts them
> > > to IOdata, and sends them to the port using file:write/2.  According
> > > to the Erlang documentation, the port should write its data when
> > > 
> > >   * 64kB of output data have accumulated, or
> > >   * when the oldest datum in the buffer reaches 2 seconds old
> > > 
> > > This is thanks to the default 'delayed_write' parameters.
> > > 
> > > My program's output turns out to be consistenly one message behind the
> > > messages being sent.  The first message "disappears" until I send the
> > > second message, at which point it appears in the file.  When I send
> > > the third message, the second one appears in the file, etc.  The last
> > > message only appears when closing the file.  The 2 second limit
> > > doesn't seem to have any effect.
> > > 
> > > Has anyone encountered this behavior before?  It's R11B-2 running on
> > > Linux.
> > > 
> > > Thanks,
> > > 
> > > Derek
> > > 
> > > -- 
> > > Derek Upham
> > > 
> > > _______________________________________________
> > > erlang-questions mailing list
> > > 
> > > http://www.erlang.org/mailman/listinfo/erlang-questions
> > 
> > -- 
> > 
> > / Raimo Niskanen, Erlang/OTP, Ericsson AB
> > _______________________________________________
> > erlang-questions mailing list
> > 
> > http://www.erlang.org/mailman/listinfo/erlang-questions

-- 

/ Raimo Niskanen, Erlang/OTP, Ericsson AB



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