"ORA-50012: Pooled connection request timed out" when timeout transaction in >= .net8

[mishustin]

Hello!

I have a simple example that reproduces the error “ORA-50012: Pooled connection request timed out”. After the error occurs, the oracle connection pool does not issue any more connections and the application hangs without accessing the database, only restarting (i.e. resetting the oracle connection pool) helps.
The error is reproduced only on versions starting from .net8, on .net6 this error is not reproduced. It occurs if the transaction timeout is less than the code execution time inside the transaction.

OS: Microsoft Windows NT 10.0.19045.0
.net version: 8.0.12
configuration buils: release
Microsoft.EntityFrameworkCore Version 8.0.12
Oracle.EntityFrameworkCore Version 8.23.70
Oracle.ManagedDataAccess.Core" Version 23.7.0

Example
https://github.com/mishustin/OracleTransactionApp/tree/ORA-50012

Is this bug?
Can you help me?

[alexkeh]

I ran your test case. For the .NET 6 setup, I see the transaction timeout. However, the .NET 8 setup doesn't trigger a transaction timeout. I suppose that means the connection time out cannot occur.

Can you generate an ODP.NET level 7 trace file, which should also indicate why the connection time out occurs?

You can also try using the ODP.NET 21c version for EF Core 8 to see if that works. There have been several changes to connection pool behavior between 21c and 23ai, one of which could be the reason for the time out you observe.

[mishustin]

You should repeat the run a few times on .net8, usually on the second or third time there is a transaction timeout and then immediately an error getting a connection from the oracle connection pool.

In this version configuration, the error “ORA-50012: Pooled connection request timed out” does not really occur and connections are returned from the connection pool after other errors, that's okay

“Microsoft.EntityFrameworkCore” Version=“8.0.12”
“Oracle.EntityFrameworkCore” Version=“8.21.170”
“Oracle.ManagedDataAccess.Core” Version=“3.21.170”

Ironically, we switched to a new version of the library to add OpenTelemetry tracing to understand the cause of the “ORA-50012: Pooled connection request timed out” error

Trace is here

ORACLETRANSACTIONAPP.EXE_PID_17040_DATE_2025_02_14_TIME_13_38_54_136029.txt

[alexkeh]

I've filed bug 37635242 to investigate this issue further. This could be an issue with supporting async transactions.

[alexkeh]

@mishustin The dev team has reviewed your issue. We believe it's a legitimate problem but have been unable to reproduce it ourselves. We suspect this is an ODP.NET timing problem but need enhanced tracing to verify. Can you open an Oracle Support service request, indicate you are hitting Bug 37635242, and request access to the diagnostic drop?

The diagnostic drop has enhanced tracing to identify the root cause.

[mishustin]

I'm sorry, but I can't access https://signon.oracle.com/signin
I'm getting an error

In compliance with U.S. and applicable Export laws we are unable to process your request to https://signon.oracle.com/signin. Please contact [email protected] if you believe you are receiving this notice in error.

Reference ID: 0.4cf2d8b.1740725524.3a98ed6

I can guess why I'm getting it.

Is there anything else I can do to help?
Was my tracing with level 7 helpful?
Maybe you need some more trace logs from my local computer?

[alexkeh]

@mishustin Yes, the trace was helpful. Since yesterday, we believe we've identified the problem. That root cause matches up with your trace (and why we've been unable to reproduce it internally). We have a good idea of what the fix is.

I don't know why you're getting the Oracle sign-on error. I've never seen it before. You can ask your DBA whether they can log in to the site. If so, they can file the SR on your behalf as well.

Since we've identified the likely root cause, the dev team will proceed with a fix. Ideally, we'd like to have this fix tested in your environment to validate it works for you. That is what we intend to do if you can log in to My Oracle Support.

[alexkeh]

@mishustin The validation fix is ready if you'd like to verify it resolves your issue. Ask your Oracle support analyst to upload it to the Oracle service request log. You can then try it out.