Debug Tutorial: How to View Process State

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process [ context ] [ change ] [ full ]

Process states fall into two general catergories, running and stopped. Many commands cannot act upon a process in a running state and will print an error if this is attempted. The halt command can be used to put a process into a stopped state so that it can be examined.

• process lists the state of all processes in the context. Any process in a stopped state includes its current location and the reason it stopped. An '*' to the left of the context column indicates a state change since the last time that process's state was displayed. (The '>' currently has no meaning.)

• A program which has been loaded is automatically executed to the first line of user code and placed in the Initial state.

• A program is automatically stopped just prior to executing the exit procedure and placed in the Exiting state. Any process continued past this point enters the Exited state and is no longer valid.

• Running states consist of Executing and Stepping. A program executing a blocking receive will be in one of these states.

• The halt command stops execution and places the process in the Interrupted state.

• A process which just completed a next, step, nexti, or stepi command will be in the Stepped state.

• A process which encountered a code or data breakpoint will be in the Breakpoint state. The number of the breakpoint encountered is included in the reason field.

• A process for which a signal has arrived is placed in the Signaled state. The name of the signal is included in the reason field. The signal handler (default or user-defined) will not be executed until execution is resumed.

• The change switch causes only processes' with a state change to be displayed. The full switch causes a procedure name to be fully qualified.

• The step, next, and wait commands automatically display process state when they complete.

Example process state display:

        Context             State      Reason    Location     Procedure
  ====================== ============ ========= ========== ====================
> (0)                    Initial                Line 16    main()
> (1,3)                  Stepped                0x0003b410 _doprnt()
>*(2)                    Stepped                Line 19    main()
> (4)                    Breakpoint   C Bp2     Line 20    main()
>*(5)                    Signaled     SIGSEGV   Line 13    one()