OS spawns multiple PIDs for one listener process

Folks:

I am seeing an unusal pattern with listener process. When starting this process, OS spawn four PIDs.
The listener.ora file is similar to what we have in other servers.

OS : Linux RHEL 4.0
DB: 10.2.0.2

Anyone experienced this/ideas?

eg:
$ ps -ef|grep tns
oracle 23119 1 0 15:37 ? 00:00:00
/ispiris-dev/orasrc/product/db/10.2.0.2/bin/tnslsnr LISTENER -inherit
oracle 23120 23119 0 15:37 ? 00:00:00
/ispiris-dev/orasrc/product/db/10.2.0.2/bin/tnslsnr LISTENER -inherit
oracle 23121 23120 0 15:37 ? 00:00:00
/ispiris-dev/orasrc/product/db/10.2.0.2/bin/tnslsnr LISTENER -inherit
oracle 23122 23120 0 15:37 ? 00:00:00
/ispiris-dev/orasrc/product/db/10.2.0.2/bin/tnslsnr LISTENER -inherit
oracle 23431 21384 0 16:10 pts/0 00:00:00 grep tns $

Thanks
Jay

--
http://www.freelists.org/webpage/oracle-l