Submitted by: Daniel H (daniel90)

Votes: 1

We are developing an http://ASP.NET Core (.NET Core Version 2.1.1) web application.
We are using a Firebird 3 Connection Pool with the following options in the connection string:

- Pooling: True
- MinPoolSize: 0
- MaxPoolSize: 50
- Auto_Commit: false
- Enlist: true

On serveral occasions we receive the following exception:
"Unable to enlist in transaction, a local transaction already exists".

This happens in our minimal breaking exampple, if we call the following code with a few threads over HTTP GET:

    \[HttpGet\]
    public async Task<IActionResult\> GetX\(\)
    \{
        IEnumerable<string\> x= null;
        using \(var ts = new TransactionScope\( TransactionScopeAsyncFlowOption\.Enabled\)\)
        \{
            using \(var connection = new FbConnection\(connectionString\)\)
            \{
                roles = await connection\.QueryAsync<string\>\(
                    sql: "SELECT strField FROM X",
                    commandType: CommandType\.Text\);
            \}
            ts\.Complete\(\);
        \}
        return Ok\(x\);
    \}

If we encapsulate the TransactionScope block with a Semaphore it runs fine.
Therefore the question: Does this library supporting multithreading or do we need to protect Firebird calls with a semaphore?