OracleCommand does not respond to cancellation

I am trying to cancel an oracle command which is calling sys.dbms_session.sleep but the cancellation signal doesn’t seem to be working. Here’s the code:

var conn = new OracleConnection(connectionString);
conn.Open();

var command = conn.CreateCommand();
command.CommandText = @"
	begin
		sys.dbms_session.sleep(5);
	end;";
var sw = Stopwatch.StartNew();

var cts = new CancellationTokenSource(delay: TimeSpan.FromSeconds(1));
cts.Token.Register(() => Console.WriteLine("canceled"));
var task = command.ExecuteNonQueryAsync(cts.Token);
try { await task; }
catch (Exception ex) { Console.WriteLine(ex.Message); } // ORA-01013: user requested cancel of current operation

Console.WriteLine(sw.Elapsed); // ~5s

The command does end up in a canceled error state, but it only transitions to that state AFTER the sleep has completed, which negates the benefit of canceling. I’m running into the same issue trying to cancel calls to DBMS_LOCK.REQUEST.

[alexkeh]

@madelson I talked with the ODP.NET dev team. This situation is one they have seen before. ODP.NET sends the cancellation call to the DB server fairly quickly. However, the PL/SQL engine itself seldom checks for these client cancellation messages, which is different from how SQL cancellations behave.

While I some on the client side would consider this a bug, the choice the PL/SQL team made means this behavior is by design. I plan to update the ODP.NET doc so that this is more clearly spelled out.

[madelson]

For anyone else who comes across this, it seems to be fixed in newer versions of Oracle itself (e. g. as of 19.0.0.0.0 it works as expected).