When debugging multiple inferiors with gdb, if one inferior exits the full debug session stops

[lostgoat]

Environment

• OS and version: Arch Linux with gdb 16.3
• VS Code: 1.103.1
• C/C++ extension: 1.26.3
• OS and version of remote machine (if applicable): n/a
• GDB / LLDB version: 16.3

Bug Summary and Steps to Reproduce

Bug Summary:

When debugging multiple inferiors in gdb, if one inferior exits the vscode debug session ends.

Steps to reproduce:

1. git clone this repo: https://github.com/lostgoat/multiinferior-repro
2. Set a breakpoint on the "parent exiting" line
3. Start the "(gdb) Launch" debug task

When running gdb with the same configuration via commandline everything works correctly. Execution pauses after the child exits, and then one can use inferior <id> to switch back to the parent and keep debugging.

Debugger Configurations

{
            "name": "(gdb) Launch",
            "type": "cppdbg",
            "preLaunchTask": "build test app",
            "request": "launch",
            "program": "${workspaceFolder}/test.out",
            "args": [],
            "stopAtEntry": false,
            "cwd": "${fileDirname}",
            "environment": [],
            "externalConsole": false,
            "MIMode": "gdb",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                },
                {
                    "description": "Keep both sides of fork",
                    "text": "set detach-on-fork off"
                },
                {
                    "description": "Allow multiple inferiors to run",
                    "text": "set schedule-multiple on"
                }
            ],
            "logging": { "engineLogging": true, "trace": true, "traceResponse": true }
        },

Debugger Logs

Output window:

Starting test
parent running 
waiting for child: 965664
parent waitpid returned: 0 - 0
child started
child looping: 0
child looping: 1
child looping: 2
child looping: 3
parent waitpid returned: 0 - 0
child looping: 4
child looping: 5
child looping: 6
child looping: 7
parent waitpid returned: 0 - 0
child looping: 8
child looping: 9
child exiting

Other Extensions

No response

Additional Information

No response

[lostgoat]

Including just a snippet of the trace debugger logs since it didn't let me paste the whole thing in the issue template:

[Thread debugging using libthread_db enabled]
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (448) ->~\"Using host libthread_db library \\\"/usr/lib/libthread_db.so.1\\\".\\n\"\n"},"seq":472}
1: (448) ->~"Using host libthread_db library \"/usr/lib/libthread_db.so.1\".\n"
--> E (output): {"type":"event","event":"output","body":{"category":"stdout","output":"Using host libthread_db library \"/usr/lib/libthread_db.so.1\".\n"},"seq":475}
Using host libthread_db library "/usr/lib/libthread_db.so.1".
<--   C (threads-10): {"command":"threads","type":"request","seq":10}
--> R (threads-10): {"type":"response","request_seq":10,"success":true,"command":"threads","body":{"threads":[{"id":965952,"name":"test.out [965952]"},{"id":965957,"name":"test.out [965957]"}]},"seq":478}
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5449) ->~\"[Inferior 2 (process 965957) exited normally]\\n\"\n"},"seq":480}
1: (5449) ->~"[Inferior 2 (process 965957) exited normally]\n"
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5450) ->=thread-exited,id=\"2\",group-id=\"i2\"\n"},"seq":482}
1: (5450) ->=thread-exited,id="2",group-id="i2"
--> E (output): {"type":"event","event":"output","body":{"category":"stdout","output":"[Inferior 2 (process 965957) exited normally]\n"},"seq":483}
[Inferior 2 (process 965957) exited normally]
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5450) ->=thread-group-exited,id=\"i2\",exit-code=\"0\"\n"},"seq":486}
1: (5450) ->=thread-group-exited,id="i2",exit-code="0"
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5450) ->*stopped,reason=\"exited-normally\"\n"},"seq":488}
1: (5450) ->*stopped,reason="exited-normally"
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5451) Send Event AD7ThreadDestroyEvent\n"},"seq":490}
1: (5451) Send Event AD7ThreadDestroyEvent
--> E (thread): {"type":"event","event":"thread","body":{"reason":"exited","threadId":965957},"seq":492}
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5452) <--gdb-exit\n"},"seq":494}
1: (5452) <--gdb-exit
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5452) ->^exit\n"},"seq":496}
1: (5452) ->^exit
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5453) ->=thread-exited,id=\"1\",group-id=\"i1\"\n"},"seq":498}
1: (5453) ->=thread-exited,id="1",group-id="i1"
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5453) ->=thread-group-exited,id=\"i1\"\n"},"seq":500}
1: (5453) ->=thread-group-exited,id="i1"
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5454) Send Event AD7ProgramDestroyEvent\n"},"seq":502}
1: (5454) Send Event AD7ProgramDestroyEvent
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"The program '/home/andres/git/multiinferior-repro/test.out' has exited with code 0 (0x00000000).\r\n\n"},"seq":504}
The program '/home/andres/git/multiinferior-repro/test.out' has exited with code 0 (0x00000000).
--> E (exited): {"type":"event","event":"exited","body":{"exitCode":0},"seq":506}
--> E (terminated): {"type":"event","event":"terminated","body":{},"seq":508}
--> E (output): {"type":"event","event":"output","body":{"category":"telemetry","output":"VS/Diagnostics/Debugger/DebugCompleted","data":{"VS.Diagnostics.Debugger.ImplementationName":"Microsoft.MIDebugEngine","VS.Diagnostics.Debugger.EngineVersion":"17.12.21003.1","VS.Diagnostics.Debugger.HostVersion":"17.12.21003.1","VS.Diagnostics.Debugger.AdapterId":"cppdbg","VS.Diagnostics.Debugger.DebugCompleted.BreakCounter":0}},"seq":510}
<--   C (disconnect-11): {"command":"disconnect","arguments":{"restart":false},"type":"request","seq":11}
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (5459) Send Event AD7ThreadDestroyEvent\n"},"seq":513}
1: (5459) Send Event AD7ThreadDestroyEvent
--> R (disconnect-11): {"type":"response","request_seq":11,"success":true,"command":"disconnect","body":{},"seq":515}

And attaching the full output as a file:

debug.txt

[github-actions]

Thank you for reporting this issue. We’ll let you know if we need more information to investigate it. Additionally, if you're working with GDB/LLDB, please note that the code is open source at https://github.com/microsoft/MIEngine/wiki/Contributing-Code . Your contributions are always welcome and appreciated.