why not build file lists in parallel?

Carlos Carvalho carlos at fisica.ufpr.br
Sun Sep 14 21:13:26 GMT 2008

It often takes rsync a long time to start transfers because of the
time to build the file lists of a (big) sync in both ends of the
connection. Usually it's not rsync's fault; most of it is spent
waiting for the machine to return stat info.

Version 3 avoids this delay by starting the transfers without waiting
for the complete file lists. However this only happens in two cases:
if version 3 runs in both ends (which is still rare) and no options
such as delay-updates are used. And this is even rarer...

The rsync client first asks for the server to send it the whole file
list, and does nothing during this period; only after having the
sender list it starts to build the local one. Why doesn't it build the
local list while waiting for the server's??? That could speed big syncs

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