Getting SYSTEM-F-NOSLOT

[Chaim Budnick]

One of our customers has a DSM application which during normal processing will create background process. The entire application was migrated to a nes server (more memory - more powerful CPU) albeit without changing any SYSGEN parameters.

The following message is being generated:

SYSTEM-F-NOSLOT

The interactive logins is et to 120
The MAXPROCESSCNT is 155
The BALSETCNT is 180

I have a command procedure which simulates what the DSM does and creates a process. If I run this consecutively 6-7 times I also receive this error. At that point the actual interactive count is around 90 +-.

What might be the problem?

Thanks,

Chaim

[Chaim Budnick]

More information:

I ran AUTOGEN SAVPARAMS TESTFILES FEEDBACK

The AGEN$PARAMS.REPORT interestingly enough contains the following:

Parameter information follows:
------------------------------

MAXPROCESSCNT parameter information:
Feedback information.
Old value was 155, New value is 217
Maximum Observed Processes: 155

What I don't understand is that I have been monitoring using SET LOGIN and have not seen a currnet interactive value greater than 95!

Yet I can generate this error at will by running the CP.

Is there a way to actually monitor the MAXPROCESSCNT and see that it really is peaking?

Chaim

[Robert Gezelter · Accepted solution]

Chaim,

The "current interactive value" displayed by SET LOGIN is the current number of users logged onto the system. It does not reflect:
- Batch Jobs
- Network Processes
- Detached Processes
- Sub-Processes

If you do a SHOW SYSTEM on the subject machine, and count the number of processes that are active, you will get a more accurate number. While your command file was not part of the posting, you are probably creating sub-processes which don't count as "interactive users", but do take up process slots.

The number recommended by AUTOGEN is the highest observed number, plus an allowance for expansion.

I suggest that you update your system parameters (or modify your observations of system utilization).

As a side note, it is not unusual these days for programs to create large numbers of short term processes (e.g., it is a common Unix paradigm). This leads to short term spikes in the process count, and similar, but often harder to diagnose versions of your problem.

I hope that the above is helpful.

- Bob Gezelter, http://www.rlgsc.com

[Jan van den Ende]

Chaim,

MAXPROCESSCNT is about _ALL_ processes in the system, not only interactive!
One easy way to monitor them is... MONITOR/SYSTEM.
The upper right quart of that display shows all processes.

Like you already found, AUTOGEN would increase the value by about 40%.
... but if you were to use that, in about a couple of days I expect AUTOGEN to raise it again by the same percentage, because AUTOGEN tends to be too conservative.

You stated having more memory. Well, put it to good use!
The expense of creating balance slots is really futile in todays amounts of memory, and if you get to the point of using them, well, that is what the system _IS_ for. (unless you have a really bad app that generates processes, and leaves them around after use, but that would surely have hit you even much heavier on your smaller system).

So, be generous, and set MAXPROCESSSCNT to something like 600, maybe 1000 or 1500.
_IF_ you do, make sure to use AUTOGEN to re-calculate all the other dependant params.
Only if the new situation has stabilized, and you got an idea how the system behaves with those, then you _might_ take a look at those others again for maybe some fine-tuning, but for a first try nothing beats AUTOGEN to make a fair first estimate!

Success.

Proost.

Have one on me.

Jan

[David B Sneddon]

Chaim,

One other consideration, from the help within SYSGEN

Never set BALSETCNT to a value higher than 2 less than
MAXPROCESSCNT.

As has been suggested -- be generous with MAXPROCESSCNT.

The SYSTEM-F-NOSLOT message is _the_ indication
that the value has peaked.

HELP/MESSAGE NOSLOT reveals...

NOSLOT, no PCB available

Facility: SYSTEM, System Services

Explanation: The maximum number of processes that can be created at one
time has been exceeded.

User Action: Wait for another process to be deleted, or increase the
MAXPROCESSCNT system parameter.


Regards
Dave

[Antoniov.]

Chaim,
only a little consideration: new slots require a few memory (around 150 byte for every slot) so it's better having much free slots avaiable than needing more.

Antonio Vigliotti