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       1           0 : // Distributed under the MIT License.
       2             : // See LICENSE.txt for details.
       3             : 
       4             : #pragma once
       5             : 
       6             : namespace sys {
       7             : /*!
       8             :  * \brief Provide an infinite loop to attach a debugger during startup. Useful
       9             :  * for debugging MPI runs.
      10             :  *
      11             :  * Each MPI rank writes a file name `spectre_pid_#_host_NAME` to the working
      12             :  * directory. This allows you to attach GDB to the running process using
      13             :  * `gdb --pid=PID`, once for each MPI rank. You must then halt the program
      14             :  * using `C-c` and then call `set var i = 7` inside GDB. Once you've done this
      15             :  * on each MPI rank, you can have each MPI rank `continue`.
      16             :  *
      17             :  * To add support for attaching to a debugger in an executable, you must add
      18             :  * `sys::attach_debugger` to the
      19             :  * `Parallel::charmxx::register_init_node_and_proc` init node functions. Then,
      20             :  * when you launch the executable launch it as
      21             :  * ```shell
      22             :  * SPECTRE_ATTACH_DEBUGGER=1 mpirun -np N ...
      23             :  * ```
      24             :  * The environment variable `SPECTRE_ATTACH_DEBUGGER` being set tells the code
      25             :  * to allow attaching from a debugger.
      26             :  */
      27           1 : void attach_debugger();
      28             : }  // namespace sys