Re: gdb drops out with 'I/O possible message'

[Daniel Jacobowitz <drow@false.org>]

On Mon, Oct 31, 2005 at 10:03:10AM +0000, Andrew Walrond wrote:
> On Monday 31 October 2005 09:43, Andreas Schwab wrote:
> >
> > Some process (ruby?) is probably enabling async I/O on stdin, which causes
> > all processes in the same process group to receive SIGIO whenever
> > something is available to be read on stdin.  Then the process crashes and
> > has no chance to disable async I/O.  With the next debugging session a new
> > process group is created, but the SIGIO signals are still sent to the old
> > (now defunct) process group, effectively dropping them on the floor.
> 
> So is gdb in the same process group as the debug target process? (FWIW the 
> process in question forks off several other processes) And will receive the 
> same SIGIOs?

It should not be; it goes to some effort to always keep the foreground
process group set correctly.

> In other (non ruby) applications where I have seen this problem, I do
> 
> 	std::ios::sync_with_stdio(false)
> 
> which presumably enables async I/O on stdin/stdout etc.

No, that has nothing to do with async I/O; it's just a question of
buffering.

-- 
Daniel Jacobowitz
CodeSourcery, LLC