On Mon, 23 May 2022, Junio C Hamano wrote:

quoted

It calls into cURL, which I suspect has a multi-threaded mode of
operation,

https://curl.se/libcurl/c/threadsafe.html ;-)

My understanding is that what we have is pretty much select() driven 
single-threaded multi-fd transfer.

Confirmed. libcurl *can* use threads (if built that way), but the only use it 
has for such subthreads is for resolving host names. libcurl, its API and its 
callbacks etc always operate in the same single thread.

-- 

  / daniel.haxx.se