Re: [Discuss-gnuradio] QT Gui mem alloc error - runs OK if R, C hints deleted

[CEL]

Hi Tom!

Hm, no, I wouldn't be aware of any limitations, and even if such exist,
things shouldn't die with a std::bad_alloc!

Ok, so I'm wondering how we can move forward with this. Let us try
this:

* Can you share a proof of failure flow graph with us? That way,
everyone's definitely talking about the same thing.
* I assume you've got GNU Radio built with debug symbols (cmake
-DCMAKE_BUILD_TYPE=RelWithDebInfo). This might even work if it wasn't,
but the backtraces below might be less exciting.
* you'll need gdb

gdb --args python2 /path/to/your/flowgraph.py⏎

(things flutter by)

(gdb)start⏎

(things flutter by)

(gdb)break std::bad_alloc::what()⏎

(it should NOT complain that this symbol isn't already loaded. If it
does, we might need to install the libststc++ debug symbols; haven't
used Ubuntu in a while, but probably `apt install libstdc++-dbg` or `-
dbgsym`)

(gdb)run⏎

(wait for the breakpoint defined above to trigger)

(gdb)info threads⏎

(this is the list of currently existing threads. Copy and save.)

(gdb)bt⏎

(short for `backtrace`. Now we should be getting a list that's
basically like "walking an onion from the middle to the peel", if
you're onion layers are defined by who called a function which called a
function...)

Share the output; if you look through it, the frame with the lowest
number that already happens somewhere inside libgnuradio-qtgui probably
contains info on where exactly that allocation happens that fails.

You can "jump" into that frame with `frame <number>`, replacing
<number> with the index given by #<number> in the backtrace. If these
variables/symbols weren't optimized away during compilation, you can
even use `print <variablename>` to print the values of local and global
variables, or use `list` to print the source code of what you're
looking at (that definitely requires debug info to be included with GNU
Radio's build).

Best regards,
Marcus

On Mon, 2018-06-25 at 16:52 -0700, Tom McDermott wrote:
> Ubuntu 16.04.3
> GRC 3.7.11.1   (from git)
> I was on 3.7.13 couple of weeks ago, completely removed all of
> gnuradio
> and rebuilt trying to debug this.  3.7.11.1 had same problem.
> 
> 
> Got back to the problem of several weeks ago.
> 
> 1. When I try to use a QT GUI sink (such as frequency) the invocation
> of
> the QT Gui Frequency sink in this example throws a memory allocation
> error.
> 
> Qt has caught an exception thrown from an event handler. Throwing
> exceptions from an event handler is not supported in Qt. You must
> reimplement QApplication::notify() and catch all exceptions there.
> 
> terminate called after throwing an instance of 'std::bad_alloc'
>   what():  std::bad_alloc
> 
> 2. If I remove the Row, Column GUI hints from just that one QT GUI
> item, then it
> comes up and runs OK. The other 9 of the QT controls (sliders,
> choosers, entry,
> ranges) still have their R,C hints.
> 
> 3. Went back to the GRC file in step 1 that still has the R,C hints
> in it
> and it still fails with the error as shown in step 1.  It did come up
> and run
> one time showing 'unable to set locale' error, but still ran.  Never
> seen that before.
> 
> 
> Is there some limitation against using R,C hints on the QT displays
> (time,
> frequency, etc.)?
> 
> -- Tom, N5EG
> 
> 
> 
> 
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> Discuss-gnuradio mailing list
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