Failed to 'continue' nginx debug through gdb attach in vscode while terminal gdb is fine

[hcnhcn012]

Type: Debugger
gdb (attach)

Describe the bug

• OS and Version: Arch Linux with kernel 4.17.5-1-ARCH
• VS Code Version: 1.25.1
• C/C++ Extension Version: 0.17.6
• Other extensions you installed (and if the issue persists after disabling them): C++ intellisence

Problem description
When I debug a nginx module, it runs find in terminal gdb but it seems not going well on vs code when I attach the nginx worker process. No errors occur when attaching the process, but I can't continue when I get a error ERROR: Command aborted. See the output window for additional details.. Here are the corresponding part of my configuration launch.json and some log screenshots. Thanks for helping me to handle it.

The debugger says PAUSED ON EXCEPTION when in function epool_wait(), but actually this function is blocked waiting for events, which is normal.

launch.json

log main

log window

log extension hosts

Debug Console

[pieandcakes]

@hcnhcn012 Please enable "logging": { "engineLogging": true" }" and rerun with trying to continue and send the log.

[hcnhcn012]

@pieandcakes engineLog.txt
Here it is :)

[pieandcakes]

Your log shows me:

1: (4722) <-1009-break-insert -f ngx_http_multipost_module.c:378
1: (4726) ->1009^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x0000000000000166",func="ngx_http_multipost_handler",file="/home/chain/Project/postGraduateProject/180710_nginx_sercure_module/Source/nginx-1.14.0/modules/multipost//ngx_http_multipost_module.c",fullname="/home/chain/Project/postGraduateProject/180710_nginx_sercure_module/Source/nginx-1.14.0/modules/multipost/ngx_http_multipost_module.c",line="378",thread-groups=["i1"],times="0",original-location="ngx_http_multipost_module.c:378"}

which tells me that gdb thinks your breakpoint is bound to an address of 0x0000000000000166 but then when we try and start running after attach, we get:

1: (4832) <--exec-continue
1: (4833) ->^running
1: (4833) ->*running,thread-id="all"
1: (4833) ->&"Warning:\n"
1: (4833) ->&"Cannot insert breakpoint 1.\n"
1: (4833) ->&"Cannot access memory at address 0x166\n"
1: (4833) ->&"\n"
1: (4833) ->^error,msg="Command aborted."

This is the message we are showing you because for some reason gdb is telling us the breakpoint is invalid, even though it was the one that set it up. I think this must result in an exception from within gdb, which is why it shows "paused on exception". This seems to be an issue in gdb. Can you downgrade/upgrade to a different version and see if it is still having the problem?

[hcnhcn012]

@pieandcakes Thanks ! :)

[pieandcakes]

@hcnhcn012 Can you share the fix you used so others who run into the same problem know what you did?

Thanks!

[gabeluci]

I'm facing this too (while debugging VLC 3.0.9, but oddly it doesn't happen with VLC 4.0.0). A workaround is described here, which is to use the GDB command delete, to delete the offending breakpoint.

So in VS Code, after you start debugging and it halts, you do this by typing:

-exec delete 1

in the debug console. Then continue execution.

The downside of course is that you have to do this every time you start debugging.