The really odd part about this bug was the lack of a cause. Sometimes I'd see that the request failed somehow (a 404 error or some error reading the response), but other times it would ... just hang. I could run the same URL through the same code again and everything would work fine. The problem did seem to occur on some domains more than on others, but I couldn't reliably duplicate it. It happened infrequently enough that I couldn't just single-step through the code to find the cause.
So I resorted to brute force. I added some tracing code and started the program, waiting for the it to hang on some URL. Sure enough, after a few minutes the bug appeared and I found out where it was hanging. It was hanging somewhere in this code:
if (response != null)
response = null;
if (streamResponse != null)
streamResponse = null;
A little more investigation showed that it was hanging in the call to response.Close. I still don't know why it happens, but I found a solution. If I abort the associated web request before trying to close the response, the hang problem goes away. I just added a call to request.Abort before the code shown above and everything seems to work.
It feels like a hack, and I'd sure like to understand what's going on that makes response.Close hang like that, but I don't have infinite time to track these things down. If you have information as to what causes this, I'd sure like to hear it.
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