cray-lgdb / attach

[jg piccinali]

Cray's lgdb is a GDB-based parallel debugger used to debug applications (CCE, PGI, GNU, INTEL * Fortran,C,C++).

Launch

brisi01: slurm/16.05.4

• module load cray-lgdb/3.0.2
• cd /scratch/santis/piccinal/lgdb.eff/
• make

cc  -g -o hello_mpi_c hello_mpi.c
ftn  -g -o hello_mpi_f hello_mpi.f90
CC  -g -o hello_mpi_cpp hello_mpi.cpp

• lgdb

dbg all> launch $a{12} ./hello_mpi_c
...
Launch complete.
a{0..11}: Initial breakpoint, main at hello_mpi.c:18

dbg all> break hello_mpi.c:21
a{0..11}: Breakpoint 1: file hello_mpi.c, line 21.

dbg all> continue

dbg all> print myRank
a{0}: 0
a{1}: 1
a{2}: 2
a{3}: 3
a{4}: 4
a{5}: 5
a{6}: 6
a{7}: 7
a{8}: 8
a{9}: 9
a{10}: 10
a{11}: 11

dbg all> quit
Shutting down debugger and killing application for 'a'.

[jg piccinali]

Attach

• cd ~/201607/SciComp.git/Training/mpiomp/ATTACH/
• cc -g -D_ATTACH mpic.c
• echo 0 > go ; srun --unbuffered -n2 ./a.out
• squeue

JOBID
400901

• lgdb

dbg all> attach $a 400901.0
Attaching to application, please wait...
...
dbg all> break mpic.c:68
a{0..1}: Breakpoint 2: file mpic.c, line 68.

dbg all> list
a{0..1}: 68   printf("%d/%d ",rank,size);
a{0..1}: 69   MPI_Finalize();
a{0..1}: 70 
a{0..1}: 71   return 0;
a{0..1}: 72 }

dbg all> print rank
a{0}: 0
a{1}: 1

dbg all> print size
a{0..1}: 2

dbg all> release $a
Shutting down debugger and resuming application for 'a'.
dbg all> quit

[jg piccinali]

• piccinal@dom:~/git/JG/debuggers_jg.git/matrixMul.cu

int main(int argc, char **argv) {
  int rank=0 ; // false
  if (rank == 0) {
    char name[255]; gethostname(name, sizeof(name)); bool attached;
    printf("rank %d: pid %d on %s ready to attach\n", rank, getpid(), name);
    while (!attached) { sleep(5); }
    }

‌

[jg piccinali]

#ifdef _ATTACH
       integer          go, cscs
       go=0
       cscs=0
        if ( myid == 0 ) then
        do while (go /= 9)
! ATTACH debugger to RUNNING JOB
! INFINITE LOOP => echo 0 > go
!       TO STOP => echo 9 > go
        OPEN(UNIT=8,FILE='go',STATUS='OLD',FORM='FORMATTED',IOSTAT=cscs)
        READ(UNIT=8,FMT='(I1)',ADVANCE='NO',IOSTAT=cscs) go
        print *,'go=',go
        CLOSE(UNIT=8)
        call sleep(5)
        enddo
        endif
#endif
! -- CSCS: infinite loop to let debugger attach to running job

‌

[jg piccinali]

#include <iostream>
#include <fstream>
#include <string>
#include <unistd.h>

int main (){
    std::ifstream myfile;
    int attached=9;
    while ( attached != 0 ) {
        myfile.open("go.txt");
        myfile >> attached;
        myfile.close();
        sleep(2);
        std::cout << "attached=" << attached << '\n';
    }
    std::cout << "END attached=" << attached << '\n';
    return 0;
}

‌