[SUMMARY]: maximum length of PID under Tru64 Unix v5.1

From: <g.j.hilbrands_at_kpn.com>
Date: Fri, 23 Mar 2001 16:25:15 +0100

Original Question:

Hello Managers,

I am wondering what the maximum lenght of a process ID within Tru64 v5.1 is.
I have seen PID's consisting of 6 positions and wonder if a pid can grow
behind this length.Any ideas, or ways to find out ?

Summary:

The pid in V5.1 is defined in /usr/include/sys/types.h as an int
(32-bits).Although there is a reference to PID_MAX in the cpid_t structure
used by thecluster software, that translates to INT_MAX that translates to
2147483647 (or 31-bits).

Now in a TruCluster Server environment, the pid is actually a structure
(cpid_t) that is split into four fields:

        pid = 19-bits
     nodeid = 8-bits
     seqnum = 4-bits
       sign = 1-bit (this is unused)

This is done to ensure that each member in a cluster has a unique pid
range(524288 unique pids/member) based on the ID of cluster member.

To ensure that PIDs are unique across a cluster, PIDs for each cluster
member are based on the member ID and are allocated from a range of numbers
unique to that member. PIDs for member 1 begin at 524,288 (2**19), and PIDs
for member 2 begin at 1,048,578, and so on.


Thanks to following people:
Scott Fafrak
Dr. Thomas Blinn
John P Speno
Alex Harkema


Met vriendelijke groet,

Gert-Jan Hilbrands
Support Unix Datacenter
> 050 - 5882781
> 06 - 51584767
> PBG 3701
> g.j.hilbrands_at_kpn.com
>
>
>
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Received on Fri Mar 23 2001 - 15:26:29 NZST

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