| Re: [cdt-dev] 'continue' executed via gdb.post_event() breaks run control inside Eclipse |
_______________________________________________Hi everyone,
I’m currently experiencing some problems with regards to how CDT behaves
in the use case described in detail below. Looks like a 'continue' executed
via GDB's python API (see gdb.post_event(event)) somehow confuses Eclipse.
How to easily reproduce the problem:
1. Use an Ubuntu/Windows host;
2. Install Eclipse C/C++ 2019.12;
3. Create a C 'hello world' app for testing; add an infinite loop in 'main';
4. Build the app;
5. Create a python script (e.g. post_event.py) and paste the following code.
Make sure to properly indent it if it gets messed-up in this email;
import gdb
class CustomEvent(object):
def __init__(self, command):
self.command = command
def __call__(self):
print("Executing <%s>" % self.command)
gdb.execute(self.command, False, False)
counter = 0
def suspend_handler(event):
global counter
if counter % 2 == 0:
gdb.post_event(CustomEvent("continue"))
counter = counter + 1
# This is not part of the suspend_handler...
gdb.events.stop.connect(suspend_handler)
6. Start local debug; use GDB 8+ in all-stop mode;
7. Run the py script using the Debugger Console - 'source post_event.py';
8. Resume the app from 'main'
9. Suspend execution - note that a 'continue' will (eventually) be executed
from the script. We have two behaviors, depending on the host OS:
a. On Linux ('enhanced' console supported), Eclipse ends-up in a weird
state, Debug view showing the app suspended (with empty stack frames) whilst
the actual app is running. Suspend button is now disabled. If I try to resume,
I obviously get an error - 'selected thread is running';
b. On Windows (no 'enhanced' debugger console support, thus no mi-async,
nor target-sync enabled), suspend operation fails with 'operation timeout'. Things
get really messy if trying other operations afterwards.
10. Repeat steps 8 and 9 if problem not reproduced after the first attempt. Seems
to be more reliable on Linux hosts but consistently failing on Windows;
I'm mentioning the 'enhanced' console support because problems seem to be related
to how app/target is interrupted - '-exec-interrupt' vs. kill(SIGINT).
From my experiments, if I switch to non-stop mode GDB, behavior on Linux does not
change, whereas on Windows I no longer see any issues. But on Windows, my setup
involves an ARM-based target, a custom GDB server and JTAG debugging. On my
Ubuntu 18.04 I simply debug a host Linux app.
Anyone else seeing this? Any hints on how to make CDT properly deal with
'continue' executed from a gdb.post_event()?
Thank you,
Adrian
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