Number of Processes and Process ID Values on HP-UX

4
PGID
See process group ID.
PID
See process ID.
pid_t
Is the C-language programmatic data type used for declaring variables which hold PID values. It has
always been and will continue to be a 32-bit integer. Its definition was introduced in HP-UX release
8.0.
process group ID
This is an integer value which is used as the handle or identifier for a process group. Its value is
usually the same as the PID of the group leader process. Also known as PGID. See setpgrp(2).
process ID
An integer value which is used as the handle or identifier for an active process. Values are reused as
processes are destroyed and new processes created (and assigned an ID previously used by some
other process). Also known as PID. Note that PIDs are also used as process group IDs (PGIDs) and
session IDs (SIDs).
process_id_min, process_id_max
Kernel tunable parameters introduced in HP-UX 11i v3. They specify the lowest and highest values to
use for process IDs when creating new processes. Their default values are 0 and 30,000,
respectively, to provide an environment compatible with that of prior versions of HP-UX.
session ID
An integer value that is used as the handle or identifier for a session. Its value is usually the same as
the process ID of the session leader process. See setsid(2).
SID
See session ID
Administrator Notes
This section covers information for the system administrator.
Kernel Tunable Parameters
Several kernel tunable parameters control the number of active processes and the values used for
PIDs:
• nproc – Specifies a limit on the total number of active processes in the system. The
maximum value for this parameter on prior HP-UX versions was 30,000. For 11i v3, it is
60,000.
2
Setting values higher than 30,000 can cause some applications to fail.
2
The software might allow the nproc value to exceed 60,000. However, larger values have not been tested by HP and are
not supported.