Hello,
I'm helping debugging a newly written .NET application running on Debian Linux 12, connecting via ODBC to an IBM i 7.3 instance running latest PTFs.
The Linux ODBC driver is 1.1.0.28, the latest one available from the IBM Debian repository.
The .NET code is heavily asynchronous, using the Blazor framework from Microsoft for .NET (
https://en.wikipedia.org/wiki/Blazor).
The code of the application is split in two. There is one part which handles the presentation through Blazor, and another part which scans configurable network ranges for certain SNMP OIDs. One part writes/updates records, the other part mainly reads records, but updates configuration tables upon user request.
Occasionally, said .NET application crashes on Linux with an entry in the kernel log:
Jun 29 17:44:07 linux kernel: [180046.651305] .NET TP Worker[13701]: segfault at 2
000002d0 ip 00007ec2238ca0b0 sp 00007ec23cdf4800 error 4 in libcwbcore.so[7ec223
800000+149000] likely on CPU 1 (core 1, socket 0)
Jun 29 17:44:07 linux kernel: [180046.651321] Code: f8 ff 4c 89 f2 48 89 c6 4c 89
e7 e8 ca 13 f9 ff 4d 85 ed 74 cd 48 89 e7 e8 1d 0e f9 ff 41 89 45 00 eb bf 0f 1f
80 00 00 00 00 <8b> af d0 02 00 00 e9 76 ff ff ff 90 0f 1f 40 00 48 8b 05 99 78
28
libcwbcore.so is part of IBM's iACS ODBC driver.
I have never encountered such a crash in years. But then, my own programming was mainly based on single threaded Perl code, and someone else did some coding in Rust. Both running on Linux, utilizing remote ODBC connecting to IBM i for database access.
This issue then turned into a Heisenbug: Adding debugging output to the .NET application did subtly change the code in a way so the bug is no longer triggered. But can we trust the application?
https://en.wikipedia.org/wiki/Heisenbug
Online research shows weak evidence that the iACS Linux driver is possibly not thread safe. Is this true?
Also, in /etc/odbcinst.ini is a parameter, "threading", being 0 upon install. Is this a pure flag, or does this influence the driver's inner workings? Could not find information online about this parameter.
Thanks!
:wq! PoC
midrange.com
