SAP Note 26455 - NT 3.51 Oracle: Work procs. hang in Reconnect

Symptom:

With NT 3.51, Oracle and R/3 Release <=3.0B, the work processes hang if the database was shut down. The work processes are not completed even if the database is booted again.

Cause and prerequisites

If the Oracle database is shut down in the current R/3 System, a work process receives an error return code from the database (for example ORA1089 or ORA1034) for a database request. Then, the work process is restarted or enters the reconnect status if the parameter rsdb/reco_trials is set (see Note 24806) and tries to reconnect itself to the database. If the database is shut down, the work process hangs when carrying out the Connect statement. The work process is not exited. It hangs even when the database is booted again. The problem was only observed up to now for NT 3.51 and Oracle (not for NT 3.5).
The cause for this behaviour is a bug in Oracle Pro*C 1.6.4. This problem was only solved with Oracle Pro*C 2.2. At the moment it is not quite clear for which Release SAP will introduce Pro*C 2.2. We do not use the Pro*C for the connect anymore as of and including Release 3.0C (instead we use Oracle Call Interface).

Solution
The hanging work processes can be found via transaction SM50. If the database is booted again and logon to the database is possible again, then the hanging work processes can be restarted in SM50 via Cancellation without core> or if this does not work with Cancellation with core>. If the majority of the work processes is affected, we recommend you to restart the R/3 application server.

The hanging of work processes can be avoided by the following work around:
Registry entry: You have to implement with regedt32 for HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE/ the value "LOCAL" with the string "T::" (for example: LOCAL:REG_SZ:T:pn1234:C11). The disadvantage of this workaround is that all connects to the database go via the TWO-TASK-MODE, that is, also those connects that are already established on the database server and who run high performing via the PIPE-MODE. However, this is no disadvantage in a decantralized system, for example, Unix Database Server and NT Application Server, because the connect to the database server takes place via the TWO-TASK-MODE anyway.

Additional key words

DB-Reconnect