#7 ZModem upload pauses when nearly done

[Thorsten Behrens]

Z-Modem uploads in Le Putty pause when they are nearly
done. ETA will be at 00:00, and there will be only a
few bytes left to transfer. At this point, upload will
pause. The length of time it pauses depends on the file
size of the uploaded file - the bigger the file, the
longer the wait. For a 20-40 MB file, I may have to
wait 4-5 minutes; for larger files, wait times of 15
minutes and up are not unusual.

CPU utilization during this wait time is low.

Example:

Bytes Sent:21094400/21095338 BPS:680464 ETA 00:00

Speculation: sz is calculating a CRC? Reading the file
byte for byte and tacking snacks between? The
correlation to file size is a clue, though I don't know
yet to what it points.

[Nicolas Barry]

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Yeah I saw that problem, the problem seems to be with the
implementation of sz that is included with Putty.
A multi mega bytes file will very quickly instantly show an
ETA of 0 seconds but the file will grow for a few minutes.
When it finally stops growing, the transfers stops.
My guess is that the version of rz you're using maybe
"preallocs" the file on disk?

I don't really have an idea on how to solve this at this point.

[Thorsten Behrens]

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Ah yes, more careful observation on my part would've been
helpful. You are right, reported upload BPS is much higher
than reported download BPS, by more than an order of magnitude.
Which means sz is not pausing when nearly done, rather it is
in the process of transferring the file while the counter
already raced ahead and declares the transfer done when, in
reality, it isn't. Which makes this a merely cosmetic issue.

I rest my case.

[Nicolas Barry]

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Good news: it seems this is now fixed (after the changes in
the way the I/Os are done in Putty).

[Thorsten Behrens]

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I still see this issue. I updated the putty.exe executable
and the sz/rz executables.