topic Re: ksh: cannot fork: too many processes in Operating System - HP-UX

ksh: cannot fork: too many processes

Manuales — Fri, 13 Oct 2006 13:13:18 GMT

what is the meaning of the following messsage ?

ksh: cannot fork: too many processes
i know that is related with a kernel parameter but i do not know which one is and what must be the new value ...

can you help me please ?

i mean:

it appears every time i run a script that only use the following commands into the file named serveruno.sh

- remsh (file into remote shell named hola.sh)
hola.sh contains:
- omnirpt command
and then (into the server where is showing the message continuew the script named server.sh working) continue the following commands:
- obtain a value that was captured as variable when remsh command was run(is the string of the file)
- send an email (email command)
ksh: cannot fork: too many processes

thanks, Manuales.

Re: ksh: cannot fork: too many processes

Pete Randall — Fri, 13 Oct 2006 13:16:25 GMT

This message means that the number of processes currently running has exceeded the kernel value nproc. You could try raising nproc and building a new kernel.

Pete

Re: ksh: cannot fork: too many processes

Manuales — Fri, 13 Oct 2006 13:17:29 GMT

Thanks Pete, but what is the new value than i have to put there in that parameter?

Re: ksh: cannot fork: too many processes

Pete Randall — Fri, 13 Oct 2006 13:18:18 GMT

Actually, come to think of it, it could be maxuprc, too.

Pete

Re: ksh: cannot fork: too many processes

Patrick Wallek — Fri, 13 Oct 2006 13:18:25 GMT

It could be one of 2 parameters: maxuprc or nproc.

maxuprc = The maximum number of processes each user can start.

nproc = The maximum number of system wide processes.

Check both parameters and see what their current values are.

ps -ef | wc -l

Will give a close count of the total number of processes on the system.

ps -ef | grep root | wc -l

will give you a count of the number of processes the root user, assuming that is who you are logged in as, is running. If you are logged in as a different user, substitute that id for root in the above statement.

Re: ksh: cannot fork: too many processes

Patrick Wallek — Fri, 13 Oct 2006 13:20:54 GMT

Only you can answer the new value question.

Depending on your settings you might want to increase the appropriate parameter by 50% or perhaps 100%.

Note that depending on the version of HP-UX you are running, this could require a reboot.

If I recall correctly, maxuprc is dynamic at 11.11 and later, but requires a reboot for 11.0 and earlier.

I believe nproc still requires a kernel recompile and a reboot for all versions.

Re: ksh: cannot fork: too many processes

Pete Randall — Fri, 13 Oct 2006 13:21:21 GMT

Increasing both of these values cost you little but a tiny bit of extra memory. I would double them and see what happens.

Pete

Re: ksh: cannot fork: too many processes

spex — Fri, 13 Oct 2006 13:21:30 GMT

Hi Manuales,

Check your scripts for unintentional looping.

maxuprc:
maximum number of processes per user
nproc: maximum number of processes system-wide

Under 11i, the default value of maxuprc is 1000, and nproc is (20+8*MAXUSERS), or 2020. maxuprc is dynamically tunable, while nproc is not.

PCS

Re: ksh: cannot fork: too many processes

Manuales — Fri, 13 Oct 2006 13:22:21 GMT

This is the result:

$ ps -fea | wc -l
336
$ ps -fea | grep root | wc -l
138 -l

maxuprc: 2048
nproc: 3220

then, do i have to replace the id that i am using by root?

Manuales.

Re: ksh: cannot fork: too many processes

Sandman! — Fri, 13 Oct 2006 13:25:30 GMT

Check your /var/adm/syslog/syslog.log file for related error messages. It will point you to the corresponding kernel parameter that needs to be changed in order to alleviate this problem. If the syslog doesn't have an entry then it's related to maxuprc.

~hope it helps

Re: ksh: cannot fork: too many processes

Patrick Wallek — Fri, 13 Oct 2006 13:27:46 GMT

Yes. If you are not logged in as root, then substitute that id for root in the 'grep' statement.

I thought I said that before.......

Re: ksh: cannot fork: too many processes

Sandman! — Fri, 13 Oct 2006 13:31:03 GMT

Adding to my last post: nproc limit exceeded will be logged to the syslog.log file but not if the limit on maxuprc is exceeded. Look in /var/adm/syslog/syslog.log file to figure out whether it's nproc or maxuprc.

~hope it helps

Re: ksh: cannot fork: too many processes

Bill Hassell — Fri, 13 Oct 2006 14:42:49 GMT

Actually, grep is seldom accurate when used with ps. Use ps as your only tool:

remsh someserver "ps -ef -u user1 | wc -l"

Also check how close the current process count is to your nproc value:

remsh someserver "sar -v 1 1 | tail -1 | awk '{print \$4}'"

It will return numbers like 356/4033 which means 356 processes running with room for a total of 4033. If you see numbers like 3999/4033 then yes, you need to DOUBLE or TRIPLE the kernel parameter NPROC. Just increasing it a little bit means you'll probably have to change it again (requires a reboot) as your system gets busier.

So you first must test your remote command that it properly works. But most important: remsh (and rexec) do NOT have a login environment. The only variables set are:

LANG
PATH
LOGNAME
SHELL
HOME
PWD
TZ

Your remote script must setup all additional variables required for proper operation. You can also trace your remote script by inserting set -x at the top.

Re: ksh: cannot fork: too many processes

Jonathan Fife — Fri, 13 Oct 2006 14:48:22 GMT

Hi Bill,

I'm just curious about this statement:
"grep is seldom accurate when used with ps. "

Can you clarify that? What should I be wary of when I use ps -ef | grep?

Thanks!

Re: ksh: cannot fork: too many processes

Peter Nikitka — Fri, 13 Oct 2006 15:20:17 GMT

Hi Jonathan,

look at the answers of me, Bill and James in the thread
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1067697

mfG Peter

Re: ksh: cannot fork: too many processes

Bill Hassell — Fri, 13 Oct 2006 22:33:14 GMT

grep matches anything on the line with the string you want. Suppose you want to find PID 123 and all processes owned by bill and all processes named "sh":

ps -ef | grep 123
(matches PID 123 1234 2123 etc)
(also matches PPID 123 1234 3123 etc)

use: ps -f -p 123

ps -ef | grep bill
(matches bill billh waybill billg etc)

use: ps -f -u bill

ps -ef | grep sh
(matches sh ksh csh bash unhasdaemon etc)

use: UNIX95= ps -f -C sh

grep is working exactly like it is supposed to but you can't tell grep to look at a certain column.

man ps has a lot of details. See especially:

-u
-p
-x
and with UNIX95=
-C
-H
-o