launchpad-dev team mailing list archive

[Jeroen Vermeulen <jtv@xxxxxxxxxxxxx>]

On 2012-06-04 20:17, Francis J. Lacoste wrote:
> On 12-06-01 06:16 PM, Stuart Bishop wrote:

> > I think there is a Storm bug, although others disagree. I'm not sure
> > why a socket going tits up is different from any other sort of
> > disconnection. At the moment, I think when the TCP connection fails
> > like this Storm doesn't reset the connection so subsequent requests
> > will also fail (it will probably get an exception it does handle
> > eventually, so the connection reopening will happen). I can fix this
> > if I can convince people it is a bug - a few of us on the team have
> > adjusted this code before as the rarer types of failed connections
> > have been discovered or changed due to updates.
>
> I'd agree with you. If the normal recovery after that kind of error is
> to reconnect and try again, Storm should do this.

It's important to tread carefully though.  Consider:

 1. Start transaction.
 2. Update data in the database.
 3. Lose connection, and implicitly, abort transaction.
 4. Restore connection and start new transaction.
 5. Update more data in the database.
 6. Commit.

In this scenario, you get a paradox where there's no trace of step 2 in 
the database and yet step 5 has definitely been committed.  So 
recovering connections is not quite as simple as it seems!


Jeroen