Debugger hangs on breakpoint (near QSGRenderThread)

mloskot

Hi,

Originally, I posted this to the qt-creator mailing list: "Debugger hangs on breakpoint (near QSGRenderThread)":http://lists.qt-project.org/pipermail/qt-creator/2013-October/002839.html
I haven't received any responses, so I decided to re-post it here trying to reach a wider community.

I'm using Qt Creator 3.0.81 (Qt 5.2.0 64-bit) on Linux, built on October 26 from the source code pulled from the Git repository. It's debug/development build and I'm using two separate copies of the build: one to develop, the other to lauch and debug a plugin.

While debugging some plugins and I've noticed that the debugging session freezes once the execution reaches some of breakpoints. It happens fairly often, but I haven't noticed the exact pattern of what kind of breakpoints actually make the debugger freeze.

For example, I placed breakpoint in the CMakeProjectManager plugin's CMakeBuildConfigurationFcatory::availaleBuilds() method, then:

the execution stops at it, then 1-5 seconds later
the stacktrace refreshes view and displays completely unrelated,
the step over/in/out buttons get disabled,
the debugger is not responding on stepping,
the only buttons that are active are pause and stop.

Here are three screenshots to show what's going on during the sequence above:

Qt Creator 1: breakpoint vs stacktrace in different thread

!http://imageshack.com/a/img577/6858/ccqe.png(Qt Creator 1: breakpoint vs stacktrace in different thread)!

Qt Creator 2: added breakpoint vs stacktrace & stop requested

!http://imageshack.com/a/img5/5714/kdn7.png(Qt Creator 2: added breakpoint vs stacktrace & stop requested)!

Qt Creator 3: added breakpoint vs stacktrace & Attempting to interrupt

!http://imageshack.com/a/img850/5031/9wvl.png(Qt Creator 3: added breakpoint vs stacktrace & Attempting to interrupt)!

Interestingly, every time it happens, the view title bar displays QSGRenderThread and "Running" next to it.

If I hit the blue pause button, it changes to "Stop requested" and eventually it shows "Attempting to interrupt" which hangs forever.

The only thing I can do is to abort debugging and restart it.

I noticed similar issue while debugging other plugins like the GenericProjectManager and others.

I wonder, is this something known?
Do I need to tweak the Qt Creator/GDB debugger settings in some way?
Does it look like a bug and shall I report?

Best regards,

Mateusz Loskot, http://mateusz.loskot.net

mloskot

FYI, this problem has been solved with "André Pönitz' diagnosis":http://lists.qt-project.org/pipermail/qt-creator/2013-October/002844.html of unclean build.

Quick tests prove that after switching to branch 3.0 and clean rebuild all works well, but I'll wait a bit and continue testing before I mark this topic as solved.