Async Web Service Calls appear to stop being processed, but remote debugger shows otherwise

I fire off about 2k async we service calls that usually take about a 30 to complete in total. Though sometimes they get stuck (visible on performance counter, asp.net, Requests Current when the requests current count does not decrease), if I attach a remote debugger, the web service appears to be being called as I would expect, though never stops being called. I can guarantee I am the only one using this service, how can I 开发者_如何转开发find out what is going on here?

This is an intermittent problem, happened about once every 5 attempts.

Turns out this was a bug with NpgSql Connection pooling. It is fixed in the latest version.