Debugging of Moose Application in VSCode in UbuntuOS

[shrituntunroy]

Hi Moose Team,

I am a new MOOSE user, currently learning to use the framework. I have a question regarding debugging a MOOSE application in VSCode on Ubuntu OS.

I am using the following launch.json configuration in VSCode:

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "by-gdb",
            "request": "launch",
            "name": "Launch(gdb)",
            "program": "${workspaceRoot}/rhocp-dbg",
            "cwd": "${workspaceRoot}",
            "programArgs": "-i examples/bcc_FeCr/test1p5/bcc_pxtal.i"
        }
    ]
}

I have two queries regarding debugging:

1. It takes a long time (4-5 minutes) for VSCode to launch the MOOSE application for debugging. Is there any way to speed up this process? My PC specs are decent: a parallel Xeon processor with 20 CPUs and 128GB RAM. I have installed MOOSE manually, compiling libmesh, PETSc, and WASP myself.

2. By default, the MOOSE application is launched in the VSCode debugger with 4 threads. Is there a way to configure it to launch with only 1 thread? I have tried the option of -n-threads=1 still MOOSE is lauched with 4 threads.

Thank you for considering my queries. I look forward to your response.

[GiudGiud]

Hello

It takes a long time (4-5 minutes) for VSCode to launch the MOOSE application for debugging

How long does it take to:

• run an opt application instead of a debugging one from VSCode?
• run the debugger outside of vscode ?

For 2, it should be --n-threads=1 not -n-threads=1, so one additional dash.
Does that work?

[shrituntunroy]

Hi Giudicelli,

Thank you for your reply. Please find the answers to your queries below:

The opt application and command line debugging in gdb start almost instantaneously.
Apologies for the typo in my previous message. I was using --n-threads=1 as intended. However, the debugger still starts with 4 threads, as shown below:

{

    "version": "0.2.0",
    "configurations": [
        {
            "type": "by-gdb",
            "request": "launch",
            "name": "Launch(gdb)",
            "program": "${workspaceRoot}/rhocp-dbg",
            "cwd": "${workspaceRoot}",
            "programArgs": "-i examples/bcc_FeCr/test1p5/bcc_pxtal.i --n-threads=1"
        }
    ]
}

[GiudGiud]

Umm. Can you step in those threads to see what they are doing?

I know one is just the perf graph thread, it does not do much

[shrituntunroy]

HI Giudicelli,
Thank you for the hint.

Below are the stack frames for each of the 4 individual MOOSE threads:

Looking at the stack frames, it seems no calculations are being carried out by the threads—they appear to be used solely for timing and monitoring purposes.

This time, I started the VSCode debugger with the following configuration:

        {
            "name": "Attach to C++ process",
            "type": "cppdbg",
            "request": "attach",
            "processId": "${command:pickProcess}",
            "program": "${workspaceFolder}/rhocp-dbg",
            "MIMode": "gdb",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ]
        }

Its relatively faster (1-2 mint). Is there any other way to speed up this lauching process.

[GiudGiud]

I dont know about the two middle threads. The last one might be the perf graph one.

@loganharbour @dschwen do you know a faster debugger configuration?

[loganharbour]

I don't. I tried quite a while ago getting some of the debugging extensions working, but ran out of patience.

[Trustpad-web]

Hello,

I understand your concerns regarding the debugging process with MOOSE in VSCode on Ubuntu. Let me try to address your queries:

1. Slow launch time for debugging:

   • The launch time for a MOOSE application can be influenced by several factors, such as the complexity of the input file, the size of the simulation, and the overall system performance.
   • Since you have a powerful machine with a Xeon processor and 128GB of RAM, the launch time should be relatively faster. However, there are a few things you can try to potentially improve the startup time:
     • Ensure that you have the latest version of VSCode and the necessary extensions installed (e.g., C/C++ extension).
     • Check if you have any other processes or applications running in the background that might be consuming system resources.
     • Consider profiling your MOOSE application to identify any potential performance bottlenecks.
     • Consult the MOOSE documentation or the MOOSE community forum for any specific recommendations or troubleshooting steps related to debugging performance.

2. Configuring the number of threads:

   • The MOOSE framework is designed to take advantage of multi-threading to improve performance. By default, it will launch the application with the maximum number of available threads on your system.
   • To configure the number of threads, you can use the --n-threads or -n command-line argument when launching your MOOSE application. For example, to run with a single thread, you can use the following in your launch.json file:

     "programArgs": "-i examples/bcc_FeCr/test1p5/bcc_pxtal.i --n-threads=1"
     

   • Alternatively, you can set the environment variable OMP_NUM_THREADS to the desired number of threads before launching the MOOSE application. For example:

     "env": {
         "OMP_NUM_THREADS": "1"
     }
     

   • Keep in mind that running with fewer threads may not necessarily improve performance, as it depends on the specific problem and the parallelization capabilities of your MOOSE application.

I hope these suggestions help you address the issues you're facing with debugging your MOOSE application in VSCode. If you continue to experience problems, don't hesitate to reach out to the MOOSE community or the MOOSE development team for further assistance.