[Qt-creator] LLDB consumes large amounts of memory (Multi Gigabytes)

[Adam Light]

On Mon, Aug 31, 2015 at 7:45 AM, Michael Jackson <imikejackson at gmail.com>
wrote:

> We are trying to use the LLDB debugger under OS X 10.10.5 with Xcode 6.4
> for our project. When using the QtCreator 3.5 release and attempting to
> stop at a break point LLDB spins up to 100% CPU and eventually uses all the
> memory on the machine (About 8 GB). I eventually have to force quit LLDB
> and basically can not debug. The version of LLDB that comes with Xcode 6.4
> is 330.0.48.
>
> Has anyone else seen this problem with QtCreator? If I generate the same
> project as an Xcode project then I have no problems stopping at breakpoints
> and no memory issues.
>
>
This is a long shot, but about a year ago, one of our developers had a
somewhat similar problem with debugging from Creator using lldb on his
Macintosh machine. Eventually, I noticed that his
~/.config/QtProject/QtCreator.ini settings file was several megabytes in
size, while mine was around 50kb. When I compared the two files, his had a
lot of binary data (stored as a QVariant) in one or two settings fields
that had to do with the debugger. I think he just deleted those settings,
saved the file, restarted Qt Creator, and things were better again.

We also occasionally have problems debugging our application in Creator
using lldb on Macintosh for a different reason. In these cases, if you show
the debugger log (click the Views button in Creator when it's in Debug mode
and then enable Debugger Log), you'll see thousands of error messages
printed out. I don't remember the exact error though. This was something
that was discussed on either this list or the Qt development list several
months ago and I think the conclusion was that it might be an Apple bug,
though we never see this kind of behavior when debugging from Xcode
directly. Sometimes if I delete my build directory and rebuild my
application, this problem will go away. Sometimes it won't, in which case I
just have to give up on debugging and start peppering the problematic code
with qDebug statements.

We're currently using Xcode 6.2 here, for what it's worth, though we've
seen this last problem for maybe a year now with older versions and still
see it on occasion.

Adam
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