[ndtrong]

Hi everyone,
I am writing a sort code to compute angle of cylinder surface.
It can run well in serial mode however, it show error when I run with parallel as:

at ??:?
[2] #1 Foam::sigSegv::sigHandler(int) at ??:?
[2] #2 ? in /lib/x86_64-linux-gnu/libc.so.6
[2] #3 ? at ??:?
[2] #4 ? at ??:?
[2] #5 ? at ??:?
[2] #6 __libc_start_main in /lib/x86_64-linux-gnu/libc.so.6
[2] #7 ? at ??:?
[DESKTOP-1SJKL58:09310] *** Process received signal ***
[DESKTOP-1SJKL58:09310] Signal: Segmentation fault (11)
[DESKTOP-1SJKL58:09310] Signal code: (-6)
[DESKTOP-1SJKL58:09310] Failing at address: 0x3e80000245e
[DESKTOP-1SJKL58:09310] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x3ef20)[0x7f35a5abef20]
[DESKTOP-1SJKL58:09310] [ 1] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0xc7)[0x7f35a5abee97]
[DESKTOP-1SJKL58:09310] [ 2] /lib/x86_64-linux-gnu/libc.so.6(+0x3ef20)[0x7f35a5abef20]
[DESKTOP-1SJKL58:09310] [ 3] CyinterFoam[0x4a3c54]
[DESKTOP-1SJKL58:09310] [ 4] CyinterFoam[0x4a416c]
[DESKTOP-1SJKL58:09310] [ 5] CyinterFoam[0x4511e6]
[DESKTOP-1SJKL58:09310] [ 6] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7)[0x7f35a5aa1b97]
[DESKTOP-1SJKL58:09310] [ 7] CyinterFoam[0x454d1a]
[DESKTOP-1SJKL58:09310] *** End of error message ***
--------------------------------------------------------------------------
mpirun noticed that process rank 2 with PID 9310 on node DESKTOP-1SJKL58 exited on signal 11 (Segmentation fault).
--------------------------------------------------------------------------

I have checked and the error maybe comes from using reduce operator, but I donot know how to correct it. Could someone help me.
It is appreciate if you can correct me with this error.
My source is as below.

Thanks

{
    const polyBoundaryMesh&  boundaryMesh = mesh.boundaryMesh();// boundary mesh
    forAll(mesh.boundary(), patch)
    {
        const word& patchName = mesh.boundary()[patch].name();              // Boundary patch name
        if(patchName == "hull")
        {
            const polyPatch& pp = boundaryMesh[patch];
            // Info <<"size of pp = " <<pp.size() <<endl;
            vector hullCenter (0, 0.01, 0);
            scalar xHull = hullCenter.x();
            scalar yHull = hullCenter.y();
            // scalar zHull = hullCenter.z();
            dimensionedScalar delX("delX", dimless, scalar(0));
            dimensionedScalar delY("delY", dimless, scalar(0));
            dimensionedScalar angle("angle", dimless, scalar(0));
            scalarField alpha(pp.size(), 0.0);
            scalarField pressure(pp.size(), 0.0);

            forAll(mesh.boundary()[patch], facei)
            {
                const label& bCell = boundaryMesh[patch].faceCells()[facei];    // Boundary cellID
                const label& face = boundaryMesh[patch].start() + facei;        // FaceID
                //get face coordinate
                scalar xF = pp.faceCentres()[facei].x();
                scalar yF = pp.faceCentres()[facei].y();
                // scalar zF = pp.faceCentres()[facei].z();                
                // to compute angle
                delX.value() = xF - xHull;
                delY.value() = yF - yHull;
                // scalar tan = delY/delX;
                angle = atan2(delY,delX);
                angle.value() = angle.value()*180/M_PI;
                // Pout <<"go here" <<endl;
                alpha[facei] = angle.value();
                //to get presure value in current cell
                pressure [facei] = p[bCell];//
            }
            reduce(alpha, sumOp<scalarField>());
            reduce(pressure, sumOp<scalarField>());
            Info <<"alpha = " <<alpha <<endl;
            Info <<"pressure = " <<pressure <<endl;
        }
    }
}

[jherb]

A shot in the dark: Are you sure, that your files pressure and alpha have the right size? The are created with size pp.size() but used with facei (which loops over the size of the face fields).
Segmentation error means you try to access part of the memory which do not belong to the program.

[ndtrong]

Originally Posted by jherb

A shot in the dark: Are you sure, that your files pressure and alpha have the right size? The are created with size pp.size() but used with facei (which loops over the size of the face fields).
Segmentation error means you try to access part of the memory which do not belong to the program.

Dear Joachim

Thanks for your comment and suggestion. I have checked and found that they have same size of element since it works only on boundary path named as "hull".
Do you have other idea?

[olesen]

Originally Posted by ndtrong

Dear Joachim

Thanks for your comment and suggestion. I have checked and found that they have same size of element since it works only on boundary path named as "hull".
Do you have other idea?

Joachim's point is that you should first check if the boundary patch "hull" has exactly the same number of faces on each processor. Even if they actually did have the exactly the same values for each processor, you should think about what you are actually asking the system to do. I can't really figure out what this could possibly mean.


In many cases you want to sum all the values in a field (local to that processor) to create a single value (eg, a scalar) and than use sumOp to reduce that across all processors. But perhaps you need something else entirely - can't really tell from your code what are trying to do.


/mark

[ndtrong]

Originally Posted by olesen

Joachim's point is that you should first check if the boundary patch "hull" has exactly the same number of faces on each processor. Even if they actually did have the exactly the same values for each processor, you should think about what you are actually asking the system to do. I can't really figure out what this could possibly mean.


In many cases you want to sum all the values in a field (local to that processor) to create a single value (eg, a scalar) and than use sumOp to reduce that across all processors. But perhaps you need something else entirely - can't really tell from your code what are trying to do.


/mark

Thanks Mark for your suggestion.
Finally I could do that by using list and gather operator, not sumOp. SumOp always give error while gatherList can do well.