nproc(5)nproc(5)NAMEnproc - limits the number of processes allowed to exist simultaneously
VALUES
Failsafe
Default
Allowed values
The system may allow settings higher than 60,000 but such values are
unsupported. Setting below interferes with the system's ability to
execute in multi-user mode. Some configurations may have a higher min‐
imum.
must be greater than
must be greater than
Recommended values
processes per processor.
DESCRIPTION
The tunable controls the absolute number of processes allowed on a sys‐
tem at any given time. Increasing it allows more processes, and lower‐
ing it restricts the number of processes.
You can determine that is too low when the message is seen in the mes‐
sage buffer. Use or to read the message buffer. This message indi‐
cates that an application was unable to create a new process. Setting
too low can cause application failures due to an inability to fork new
processes.
You can determine how many processes have been used simultaneously by
calling and examining the This field indicates the "high water" mark of
the number of processes that have been simultaneously used.
Who Is Expected to Change This Tunable?
Anyone expecting to run large numbers of processes.
Restrictions on Changing
None. This tunable is dynamic.
When Should the Value of This Tunable Be Raised?
Increase the value of when running large numbers of processes simulta‐
neously.
What are the Side Effects of Raising the Value?
None.
When Should the Value of This Tunable Be Lowered?
Lower the value only to limit the number of processes on the system, or
when there is memory pressure and the value of is far above the
expected usage.
What are the Side Effects of Lowering the Value?
Lowering the value increases the risk of application failure due to the
inability to fork new processes.
What Other Tunable Values Should Be Changed at the Same Time?
Increase to ensure there are sufficient threads for each process.
Adjust as the default formula is multiple of
A single user may not consume all processes on the system (see
Some of these other tunables used to adjust automatically. These
adjustments must now be made explicitly.
Other tunables may require a reboot to take effect. So, dramatic
increases in the value of without reboot should be made with caution.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parame‐
ter may be removed or have its meaning changed in future releases of
HP-UX.
The effective number of processes allowed to exist simultaneously may
be affected by the values of the tunables and
Some applications may have been coded with a built-in assumption that
the number of processes cannot exceed 30,000, which was the maximum
imposed by prior versions of HP-UX. Such applications may fail on con‐
figurations which allow and/or create more than 30,000 processes.
The HP-UX kernel creates internal data structures optimized for the
value of the tunable parameter at boot time. After significant changes
to the tunable it is recommended that a reboot be scheduled so that the
kernel can reoptimize these internal data structures.
Installation of optional kernel software, from HP or other vendors, may
cause changes to tunable parameter values. After installation, some
tunable parameters may no longer be at the default or recommended val‐
ues. For information about the effects of installation on tunable val‐
ues, consult the documentation for the kernel software being installed.
For information about optional kernel software that was factory
installed on your system, see at
AUTHOR
was developed by HP.
SEE ALSOksi_alloc_max(5), maxuprc(5), nkthread(5), process_id_max(5),
process_id_min(5).
whitepaper, available on
Tunable Kernel Parameters nproc(5)
