Re: MI output command error

[Peter D HUERTER <pete.huerter@st.com>]

Eli Zaretskii wrote:

>>From: Nick Roberts <nickrob@snap.net.nz>
>>Date: Sun, 13 Mar 2005 22:35:02 +1300
>>Cc: drow@false.org, dave.korn@artimi.com, kostik@ispras.ru,
>>	gdb@sources.redhat.com
>>
>> > I'm all for documenting this in some useful way, but I fail to see how
>> > could this be done.  Describing the async operation itself is already
>> > a big challenge, as the details are extremely confusing, unless you've
>> > read the code several times and have a good understanding of the
>> > underlying system calls (like `poll' and `select').  Differences
>> > between interpreters add another dimension of complexity to this.
>>
>>Well for someone to be able to code it must mean that it can be documented.
>>But if you mean that those who did the coding are no longer available to
>>do the documenting, then I can see this would be a difficult task.
>>    
>>
>
>People who code are generally never available for documenting (present
>company excluded), that's why gdbint.texinfo is in such poor shape ;-)
>
>But what I meant was that, knowing what I do about the event loop, I
>don't know how to document it in a useful way, because talking about
>async operation is generally hard.  Of course, I will applaud anyone
>who tries, and will try to help such an effort ion any way I can.
>
>  
>
>>Actually if the asynchronous operation was working, I'm not sure what I would
>>do with it. When I debug, I'm used to waiting for execution to stop.
>>    
>>
>
>Precisely.  That is one reason why async CLI operation was never fully
>implemented: the event loop is ready for it, but the CLI layer simply
>waits until some event comes in.
>  
>
Asynchronous mode allows for a "halt" command to be used to stop a 
program (instead of ^C for example).  This is important for debugging 
thread-parallel and process-parallel programs.  E.g. when debugging an 
MPI-CH program that runs into deadlock, using ^C is not an option 
because it kills the background listener processes which may not be 
under the control of the debugger.

In the context of parallel debugging, ptools.org describes asynchronous 
command mode.  The old HPDF (High Performance Debugging Forum) initiative.

Pete.