Breakpoints not working with remote debugging with handled exceptions

[DonJayamanne]

Environment data

• PTVSD version: Master
• OS and version: N/A (but tested on Windows)
• Python version (& distribution if applicable, e.g. Anaconda): XXX
• Using VS Code or Visual Studio: VSC
• Though this is remote debugging, everything is local, both debugger and program

Actual behavior

Debugger does not break at breakpoints when there's a handled exception.

Expected behavior

Debugger should break at breakpoints.

This used to work in 4.1.1a5

Steps to reproduce:

• Start the following code for remote debugging:

import time

import ptvsd
ptvsd.enable_attach()

for i in range(1000):
    time.sleep(1)
	print(i)
	try:
		raise ArithmeticError()
	except Exception:
		pass

• Go into VSC
• Ensure the settings in Breakpoints of VSC are as follows (default):
  [ ] Raised Exceptions
  [x] Uncaught Exceptions
• Attach the debugger (for remote debugging)
• Observe how debugger breaks on the exception (issue reported Debugger always breaks into handled exceptions in remote debugging #580)
• Add a breakpoint to the line time.sleep(1)
• Hit continue button
• Breakpoint is not hit

This seems to reproduce only when we have handled exceptions. So please look into this after resolving #580

[karthiknadig]

Does not repro on Windows or Linux.

[DonJayamanne]

Please confirm that you can replicate it on Windows

[fabioz]

This is the same thing as #580 (that exception is considered unhandled even though it's handled because it's in the topmost frame during a remote attach), which is also probably why @karthiknadig is not being able to reproduce (it depends on whether it was started with the -m switch or not).

You can confirm that by putting the code inside a method:

import time

import ptvsd
ptvsd.enable_attach()

def main():
    for i in range(1000):
        time.sleep(1)
        print(i)
        try:
            raise ArithmeticError()
        except Exception:
            pass

main()