从连接读取数据时出错

Question

We have written several C# web services that have a connection to our internal Firebird 2.5.5 database.

Unfortunately the exception "Error reading data from the connection" is thrown more and more often and we don't know how to fix it.

We tried to disable pooling but this did not have the desired effect.

We also wrote a try catch block that reconnects and re-executes the SQL, but this does not seem to us to be the right solution.

Is there another option?

Here are some environment informations:

• C# 7.0
• .NET 4.5
• Firebird Version 2.5.5
• Firebird Driver 5.5.0
• The Firebird log does not show any error messages at that time
• The error happens from time to time with any sql statement

Answer 1

The problem is relatively simple: the network connection between client and server is interrupted or broken for some reason, but the State of the client connection remains Open - even though you cannot use that connection anymore. Unfortunately Firebird decided to not update this status to Broken automatically, which would make a lot more sense if you ask me.

You already figured out that reopening the connection "somewhat fixes" the problem, and we have discussed that you could do this only when FbException.ErrorCode is 335544726.

Unfortunately this does mean that any open transaction is also lost, and you cannot commit any data from it anymore. The only way I could think of to reliably recover from this situation is to rethrow the exception:

try
{
    // ...
}
catch (FbException ex)
{
    if (ex.ErrorCode == 335544726)
    {
        // close the connection (reopen depending on your application)
    }

    throw;
}

This way, you can catch this exception at a higher level in your application, and deal with it however is appropriate at that point - ie. retrying the entire transaction, or letting the user choose what to do.