What Is the CLI

The CLI and TotalView are tools that give you visibility into, and control over, your programs. These programs can already be executing or you can load them into memory directly under their control.

The executing program has one or more processes, each associated with an executable (and perhaps one or more shared libraries) and each occupying a memory address space. Every process, in turn, has one or more threads, each with its own set of registers and its own stack.

The program being debugged is the complete set of threads and communicating processes that make up an application. The exact number of processes and threads depends on many factors, including how you wrote the program, the transformations performed by the compiler, the way the program was invoked, and the sequence of events that occur during execution. Thus, the number of processes and threads usually changes while your program executes.

Some operating systems, compilers, and run-time systems impose restrictions on the relationship between processes, threads, and executables. SPMD (Single Program Multiple Data) programs are parallel programs involving just one executable, executed by multiple threads and processes. MPMD (Multiple Program Multiple Data) programs involve multiple executables, each executed by one or more threads and processes.