[Unison-hackers] multi-hour delay when sync'ing moderate-size file systems with many path elements

[Seth Teller]

hello folks,

when using unison to sync moderately-large file systems (several
thousand files, some of them large) with roughly a dozen unison
path elements, i observe a very long delay between unison's search
for updates, and the actual data transfer/sync step.

the delay does not seem to be due to network bandwidth, since
there is a fast network between the two machines.  it may be
due to CPU limitations on either end or to disk bandwidth
limits.

in any event, the delay is so long that often the update fails
because my kerberos tickets expire, and the processes involved
lose the the access permissions needed to finish the job.

i have already tried using -fastcheck, which doesn't help.

if i reduce the unison path to one element, and rerun, usually
things work.  but this is a pain because it requires manually
editing the unison profile, and restarting, many times.

can unison be forced to run in a mode in which it analyzes and
synchronizes one path element at a time, rather than analyzing
all of them, then resolving all of them?  this would be an
improvement, in that i could just run it repeatedly with a full
path, and let it make a few hours of progress each time.

can anyone suggest any other workarounds, or even suggest a bug
fix?  setting the output to verbose generates so much spurious
output that it hasn't helped me understand where the problem lies.

thanks,

seth teller