[OSM-dev] Handling 500 errors

[Dave Hansen]

The TIGER upload gets a 500 error back from the server about every 1,000
uploads.  I want to be sure to be nice to the server, so what's an
appropriate action to take when we start to get these?

Right now, I sleep for 2 seconds, and double the sleep for every
consecutive error, up to 7 times when I just stop the upload (this
hasn't happened just yet).

What do these errors actually _mean_?  Is the server just overloaded?
Can we teach the server to handle these a bit more gracefully so the
clients don't have to?

Can the server detect when it is getting into these conditions, and
perhaps return 503 errors?  

http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
> 10.5.4 503 Service Unavailable
> The server is currently unable to handle the request due to a
> temporary overloading or maintenance of the server. The implication is
> that this is a temporary condition which will be alleviated after some
> delay. If known, the length of the delay MAY be indicated in a
> Retry-After header. If no Retry-After is given, the client SHOULD
> handle the response as it would for a 500 response.

We could easily design the OSM clients to obey the Retry-After headers
to back off properly.

-- Dave