Debugging: "warning: process x is already traced by process y"

Creaperdown

When I try to start debugging with Qt Creator I get an error telling me that the process is already traced by something. When I try killing it kill y after stopping the debugging, it tells me that the process doesn't exist.

This is my output:

>&"attach 5260\n"
>~"Attaching to process 5260\n"
>&"warning: process 5260 is already traced by process 5258\n"
 process 5260 is already traced by process 5258
>&"ptrace: Operation not permitted.\n"
>79^error,msg="warning: process 5260 is already traced by process 5258\nptrace: Operation not permitted."
dwarning: process 5260 is already traced by process 5258
dptrace: Operation not permitted.
dNOTE: ENGINE ILL ******
dState changed from EngineRunRequested(3) to EngineShutdownRequested(14)
dCALL: SHUTDOWN ENGINE
dINITIATE GDBENGINE SHUTDOWN, PROC STATE: 2
<80python theDumper.exitGdb({"token":80})

>&"python theDumper.exitGdb({\"token\":80})\n"
dGDB PROCESS FINISHED, status 0, exit code 0 (0x0)
dNOTE: ENGINE SHUTDOWN FINISHED
dState changed from EngineShutdownRequested(14) to EngineShutdownFinished(15)
 Debugger finished.
dState changed from EngineShutdownFinished(15) to DebuggerFinished(16)

After trying it multiple times, it starts working for a few times, and fails again after that.

JonB

@Creaperdown
Did you look to see what process #5258 was when this happened? Another instance of gdb or Creator?

If you try debugging with gdb from a shell does it work OK?

You should probably state your platform details, how installed and what version of Creator.

Creaperdown

@JonB I have Qt Creator 11, I installed it via the online installer, debugging worked until ~1 month ago (I am not sure what triggered it). I am on Manjaro Linux and debugging with gdb on the command line works fine.

When inspecting the other process that is already tracing my project, I get:

ps -p 8114
PID TTY          TIME CMD
8114 pts/2    00:00:00 qtcreator_proce

JonB

@Creaperdown
https://forum.qt.io/topic/147260/qt-creator-11-can-t-debug-using-terminal seems to be reporting the same issue as you? There the OP says only happens when using Run in Terminal, does that apply to you?

Creaperdown

This post is deleted!

Creaperdown

@JonB Yes, it works when deselecting the "Run in terminal". I suppose this is a Qt Creator 11 bug then?

JonB

@Creaperdown
It does look like it....

Yep, see https://bugreports.qt.io/browse/QTCREATORBUG-29231
That indicates it is fixed in Qt Creator 11.0.0-beta2 ?
In which case https://www.qt.io/blog/qt-creator-11-beta2-released

UPDATE See https://forum.qt.io/topic/147260/qt-creator-11-can-t-debug-using-terminal/6

Marcus Tillmanns

@Creaperdown said in Debugging: "warning: process x is already traced by process y":

process 5260 is already traced by process 5258

Can you try the solution described here: https://rajeeshknambiar.wordpress.com/2015/07/16/attaching-debugger-and-ptrace_scope/ ?

Thanks!