SAP Note 15129 - No work process exists for shadow process

Symptom:

ORACLE shadow process does not have an R/3 work process
- and may require a high percentage of CPU time, which worsens
performance of the R/3 system.

Cause and prerequisites

Unclear - may be network problem / TCP-IP

Solution
Solution 1: (risky)
Once you have used ST04 (-> Detail analysis menu -> ORACLE session)
to find out that the shadow process no longer is part of R/3 AND
no other user is running an application on the ORACLE DB, you can
use "kill -2 " to shut down the process.

Solution 2: (certain)
It is better to shut down R/3 and ORACLE, and then to delete the
process (in case it has not been killed already during shutdown)

Of course, solution 2 is preferred.