This chapter describes the pdbx debugger. This debugger extends the dbx debugger's line-oriented interface and subcommands. Some of these subcommands, however, have been modified for use on parallel programs. The pdbx debugger is a POE application with some modifications on the home node to provide a user interface.
Before invoking a parallel program using pdbx for interactive debugging, you first need to compile the program and set up the execution environment. See IBM Parallel Environment for AIX: Operation and Use, Volume 1, Using the Parallel Operating Environment for more information on the following:
Using the debugger on optimized code may produce inconsistent and erroneous results. For more information on the -g and -O compiler options, refer to their use on other compiler commands such as cc and xlf. These compiler commands are described in AIX 5L Version 5.1 Commands Reference or your online manual pages.
source level debugging, pdbx requires the source files to be available as well. You will generally use the same mechanism to make the source files accessible as you used for the application program.
As you read these steps, keep in mind that pdbx accepts almost all the option flags that poe accepts, and responds to the same environment variables.
Also, throughout this book, keep in mind the following information.
The pSeries or RS/6000 processors of your system are called processor nodes. A parallel program executes as a number of individual, but related, parallel tasks on a number of your system's processor nodes. The group of parallel tasks is called a partition. The processor nodes are connected on the same network, so the parallel tasks of your partition can communicate to exchange data or synchronize execution.