Re: URGENT: Pro*C, OCI Lda_Def and Fork Problem

In article <38BF29B0.A6A0AB5E_at_alcatel.com.au>,   Joe Spanicek <Joe.Spanicek_at_alcatel.com.au> wrote:
>
> Hello All,
>
> I am having problems using Pro*C OCI interface connecting to a Oracle
> database while forking processes.
>

It is not recommended or really supported to have a connection open and then do a fork() (vfork() *might* be OK but not fork()).

there are too many shared resources (files, sockets and the like) that the child and parent will end up stomping all over each other. You might have it work on version x.y.z to find it won't on version a.b.c or on OS platform "x" but not OS platform "y".

You should log off, fork, log on (or better yet, fork and then log on for the first time)

The best thing to do is to disconnect the parent process before spawning the child process. The child process can then establish its own connection to the database. When the child process finishes, the parent process can reconnect if necessary.

If the parent process and the child process must both be connected to the database at the same time, we recommend that you fork your child process before connecting the parent process. After forking, you should then connect the child process using the EXEC SQL CONNECT ... AT DBNAME ... syntax and then establish your parent process using a different AT DBNAME clause. Any other SQL commands after that should also use the AT DBNAME syntax to distinguish between the parent and child process. Establishing multiple
connections is documented in the Programmer's Guide to Oracle Precompilers

The reason for connecting in this order is that if the parent connects,
the process is forked, and then the parent disconnects, an ORA-03113 error will occur. Another scenario is if the parent process establishes a
database connection, executes some SQL statements, and then spawns a child process which also executes some SQL statements. You then return to the parent process and try to execute another SQL statement or a COMMITT and you get the Oracle error ORA-01012. When you connect to the database a shadow process is started which communicates with the user process. When you fork a new process while connected, you end up with two user processes and only one shadow process. The result is that the two user processes interfere with each other. SQL*Net expects to see only one user process and one shadow process. Sometimes forking with open connections and sharing connections will work and sometimes it will not [snip]

>
> Regards
>
> Joe Spanicek
>

--
Thomas Kyte                              tkyte_at_us.oracle.com
Oracle Service Industries
http://osi.oracle.com/~tkyte/index.html
--
Opinions are mine and do not necessarily reflect those of Oracle Corp


Sent via Deja.com http://www.deja.com/
Before you buy.