Hello Ruben!

On Mon, Sep 10, 2012 at 5:33 AM, Ruben Van Boxem
<[email protected]> wrote:
> 2012/9/1 asmwarrior <[email protected]>
>>
>> On 2012-9-1 0:00, Loaden wrote:
>> > 2012/8/31 K. Frank <[email protected]
>> > <mailto:[email protected]>>
>> >
>> >     Also, I've had a problem with recent versions of mingw-w64 gdb.
>> > It's slow
>> >     as molasses loading up and/or initializing an application (minutes),
>> > but
>> >     once the application starts, it seems to be fine. (I don't think
>> > that this is
>> >     Qt specific.)
>> >
>> > Because it's using python by default.
>>
>> Why do you think it was cause by python?
>>
>> I do not have such issue when loading a vary large app. (Either gdb or gdb
>> with python enabled)
>
>
> Neither do I. You are seemingly all talking about my python-enabled gdb I
> built and configured when Qt Creator was complaining about missing python
> support in gdb and refusing to start apps in debug mode.
>
> Aside from that, I never had any speed issues with gdb and any apps I tried
> debugging.

Let me confirm that I do have slow gdb "start-up" times when debugging
Qt applications.

See, for example, this message:

   http://sourceforge.net/mailarchive/message.php?msg_id=29571140

Summarizing briefly, running

   gdb some_qt_app.exe

starts out okay, but when executing "run" from the gdb prompt, it
takes several minutes for the app to launch.  After the app launches
things appear to work okay.

Some additional minor notes:

I have no idea whether python is in any way related to this issue,
but it is the case that my copy of gdb is "python-enabled."  (Or
at least it seems to be in that if I hide

   .\x86_64-w64-mingw32-gcc-4.7.0-stdthread_rubenvb\mingw64\bin\python27.dll

gdb won't start.)

I went back and tested gdb with a trivial hello-world application, and it
appears to work fine.  I see no obvious slowness (or other issues).

I have no idea whether the issue I am seeing is specific to Qt, or is
triggered by the fact that my Qt applications (even simple, "small"
ones) are "large" and link to some "large" dll's.

If memory serves, I have seen this with another mingw-w64 version
of gdb, I think also from one of Ruben's builds.  But I wouldn't swear
to it, and, in any event, I don't have the details.

> You cannot disable python in a python-enabled gdb. It is a build-time
> configuration thing, and you need a seperate gdb build to change the python
> stuff.

Makes sense -- that's what I expected.

I'm not using python for anything, so I don't care one way or another.
If not using python would solve the slow gdb start-up problem, I'd give
it a try, but, if I understand you correctly, you're saying that that's not
the problem.

> It isn't that hard to build yourself actually.
>
> If you need any other information, please ask.

Okay, I will ...

Does anyone else see the slowness when first executing "run"
when debugging a Qt gui application with gdb?

Can anyone proactively confirm that the slowness does not occur
with some specific mingw-w64 build (preferably 4.7.0 or later) when
using gdb to debug a Qt gui application built with that mingw-w64
build?  If so, what mingw-w64 build would that be?

> Ruben
>
> PS: I obviously vote for my builds as at least a base for the "Qt
> toolchain". I will be glad to help in an effort to build/maintain such a
> thing.

I also vote for using Ruben's builds for the "Qt toolchain."  This is purely
selfish on my part, but I've been having good results with Ruben's builds,
and if Qt happens to choose the same compiler that I'm using, then I
would be able to experiment more easily with new versions of Qt, because
I wouldn't have to build Qt myself.

Thanks in advance for any information / solutions on the gdb slowness
problem.


K. Frank

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