Re: hidden buffers for async

[Richard Stallman]

    The advantage of multiple buffers is that the downloaded files can be
    viewed straight away, with no further copying.

I am not sure what you're really trying to do here.
Is your goal to ultimately have each message in a separate buffer?
Or is the goal to write them into files on disk?

    > That should work, if it is ok to do only 20 transfers in parallel.
    > It should block, not error, when all are in use.

    Why?

I suspect we are miscommunicating, talking about different levels
of code.  However, I can't see why it could be useful for any
level whatsoever to get an error just because someone asks it to
download more than 20 messages.