[cx-oracle-users] Oracle crash with CLOB and threading

[Torsten P. <Tor...@to...>]

Hello,

my collegue sent this mail today but has not subscribed to the mailing list 
probably.


Mail from Rog...@to...:

Hi,

I am having some problems with cx_Oracle, threads and clob's and am looking for 
some guidance.

For the record:
	The system is "SunOS tmxd01 5.9 Generic_112233-10 sun4u sparc"
	cx_Oracle version is cx_Oracle-4.2.1
	Oracle version is: Oracle9i Enterprise Edition Release 9.2.0.7.0 - 64bit 
Production
	Python 2.2.2 (#10, Mar 19 2003, 14:11:47)

When manipulating clobs in the database I occasionally got an Oracle error:

	OCI-21500: internal error code, arguments: [nnnnn], [], [], [], [], [], [], []

I have a test program that can now reproduce the problem at will, by repeatedly 
inserting, selecting and deleting 
on a table containing a clob from several threads. The error output looks like 
this:

OCI-21500: internal error code, arguments: [17099], [], [], [], [], [], [], []
Errors in file :
OCI-21500: internal error code, arguments: [17099], [], [], [], [], [], [], []

----- Call Stack Trace -----
NOTE: <PLT>+offset is used to represent that the
      function being called is offset bytes from
      the _PROCEDURE_LINKAGE_TABLE_.
calling              call     entry                argument values in hex
location             type     point                (? means dubious value)
-------------------- -------- -------------------- ----------------------------
Segmentation Fault(coredump)

Note that Oracle coredumps trying to print the stack trace.

Change the data type from clob to varchar, and the problem disappears.

I can also get rid of the problem by opening connections discreetly instead of 
using the 
cx_Oracle.SessionPool object, which surprised me rather.

I am currently looking at the SessionPool, and clob object code in cx_Oracle 
(Sadly, I am no expert with Python extensions),  maybe there is some issue with 
reference counts?

Any advice would be gratefully accepted.....

The test program and sql script is attached to this e-mail (thread_test_clob.py 
and tables_clob.sql)

Thanks in advance...

Roger