How To Perform Post-Request Async Processing

[Russell Fine]

I'm wondering if I can have Varnish perform any post-processing on a
request after returning a response to the client.  The project I'm
working on is a high volume http request logging and redirection
system.  I want to make sure that the clients receive a very fast
response (usually just an empty file with a 200, optionally a single
pixel graphic).  The primary reason for the request is for logging,
not to perform a client action.

However after the request occurs, I want to perform some specialized
logging and perhaps transforms/analyses.  These actions may take a
couple of seconds and I don't want the client response to wait.  One
option is to just read and continuously parse the log files, but that
seems inelegant.

1 - Can Varnish perform any post-processing on a request after
returning the response?

Thanks,

Russell