File Upload over AWS - performance problem


I allow my users to upload files over an Action Web Service, the service
uses attachment_fu with amazon s3 storage. My application is server with
a combination of apache 2.2 with a 4 mongrel cluster.

When a user is uploading a file, does the mongrel thread lock? If
another user’s request is assigned to this mongrel thread while the
original upload is taking place, will they potentially be waiting for
the upload to complete?

I am trying to track down the cause of a performance issue that I am
experiencing. From time to time mongrel threads seem to lock until I
restart the mongrel cluster. While this is happening, any requests that
are assigned to these dead mongrel threads timeout.

I would appreciate if anyone could provide any insight here.