nkthread(5) File Formats Manual nkthread(5)
NAME
nkthread - limits the number of threads allowed to run simultaneously
VALUES
Failsafe
Default
or
Allowed values
must be greater than
must be greater than
This may be set higher, but more will not be used.
Recommended values
Unless there are heavily threaded applications on the system, the default formula is adequate if is tuned correctly.
DESCRIPTION
The tunable controls the absolute number of threads allowed on a system at any given time. Increasing it will allow more threads, and low-
ering it will restrict the number of threads.
It can be determined that is too low when the message is seen in the message buffer. The message can be read via or This message indicates
that an application was unable to create a thread. Setting too low can cause application failures due to an inability to create new
threads or fork new processes.
It can be determined how many threads have been used simultaneously prior to the above message by calling and examining the This field
indicates the "high water" mark of the number of threads that have been simultaneously used.
Who Is Expected to Change This Tunable?
Anyone expecting to run large numbers of threads.
Restrictions on Changing
None. This tunable is dynamic.
When Should the Value of This Tunable Be Raised?
This value should be increased, either directly or as a result of tuning on most systems that are running many threads or processes.
What are the Side Effects of Raising the Value?
None.
When Should the Value of This Tunable Be Lowered?
The value should be lowered only to limit the number of threads 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?
Increased risk of application failure do to the inability to create new threads or fork new processes.
What Other Tunable Values Should Be Changed at the Same Time?
None.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its meaning changed in future releases of
HP-UX.
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 values. For information about the effects of installation on tun-
able values, 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 ALSO
max_thread_proc(5), nproc(5).
Tunable Kernel Parameters nkthread(5)