LGDB debugger

lgdb is a GDB-based parallel debugger used to debug applications compiled with Cray Compiler Environment, GNU, and Intel Fortran, C and C++ compilers. It allows programmers to either launch an application or attach to an already running application that was launched with aprun. Additionally, it provides comparative debugging technology that enables programmers to compare data structures between two executing applications. Comparative debugging should be used in conjunction with the CCDB GUI tool accessed by loading the cray-ccdb module

When using lgdb on a Cray system, remember that you use lgdb to launch an instance of aprun, which in turn launches the application to be debugged. You cannot use lgdb to launch an application directly.

Available Version: 3.0.7

To load the module

module load cray-lgdb

Example 1 Launching and debugging a single-rank application

$ lgdb –pes=0 –command=”aprun -n1 ./myapp” –lib=/lib64/libthread_db.so.1

You must specify the number of PEs (ranks) to which you want to attach gdbservers. Since this is a single-rank application, specify 0 for the rank.The –lib=path_to_library is optional and needs to be specified only for certain systems, such as X86_64 Linux, where the libthread_db library is required.

Example 2 Attaching to an already-running application

$ lgdb –pes=0 –command=”aprun -n1 ./myapp” –lib=/lib64/libthread_db.so.1

You must specify the number of PEs (ranks) to which you want to attach gdbservers. Since this is a single-rank application, specify 0 for the rank.The –lib=path_to_library is optional and needs to be specified only for certain systems, such as X86_64 Linux, where the libthread_db library is required.

Documentation: