Hello Thomas,
14.09.2024 23:32, Thomas Munro wrote:
On Sun, Sep 15, 2024 at 1:00 AM Alexander Lakhin <exclus...@gmail.com> wrote:
(That is, 0.1-0.2 MB leaks per one robocopy run.)
I observed this on Windows 10 (Version 10.0.19045.4780), with all updates
installed, but not on Windows Server 2016 (10.0.14393.0). Moreover, using
robocopy v14393 on Windows 10 doesn't affect the issue.
I don't understand Windows but that seems pretty weird to me, as it
seems to imply that a driver or something fairly low level inside the
kernel is leaking objects (at least by simple minded analogies to
operating systems I understand better). Either that or robocop.exe
has userspace stuff involving at least one thread still running
somewhere after it's exited, but that seems unlikely as I guess you'd
have noticed that...
Yes, I see no robocopy process left after the test, and I think userspace
threads would not survive logoff.
Just a thought: I was surveying the block cloning landscape across
OSes and filesystems while looking into clone-based CREATE DATABASE
(CF #4886) and also while thinking about the new TAP test initdb
template copy trick, is that robocopy.exe tries to use Windows' block
cloning magic, just like cp on recent Linux and FreeBSD systems (at
one point I was wondering if that was causing some funky extra flush
stalls on some systems, I need to come back to that...). It probably
doesn't actually work unless you have Windows 11 kernel with DevDrive
enabled (from reading, no Windows here), but I guess it still probably
uses the new system interfaces, probably something like CopyFileEx().
Does it still leak if you use /nooffload or /noclone?
I tested the following (with the script above):
Windows 10 (Version 10.0.19045.4780):
robocopy.exe (10.0.19041.4717) /NOOFFLOAD
iteration 1
496611328
...
iteration 1000
609701888
That is, it leaks
/NOCLONE is not supported by that robocopy version:
ERROR : Invalid Parameter #1 : "/NOCLONE"
Then, Windows 11 (Version 10.0.22000.613), robocopy 10.0.22000.469:
iteration 1
141217792
...
iteration 996
151670784
...
iteration 997
152817664
...
iteration 1000
151674880
That is, it doesn't leak.
robocopy.exe /NOOFFLOAD
iteration 1
152666112
...
iteration 1000
153341952
No leak.
/NOCLONE is not supported by that robocopy version:
Then I updated that Windows 11 to Version 10.0.22000.2538 (with KB5031358),
robocopy 10.0.22000.1516:
iteration 1
122753024
...
iteration 1000
244674560
It does leak.
robocopy /NOOFFLOAD
iteration 1
167522304
...
iteration 1000
283484160
It leaks as well.
Finally, I've installed newest Windows 11 Version 10.0.22631.4169, with
robocopy 10.0.22621.3672:
Non-paged pool increased from 133 to 380 MB after 1000 robocopy runs.
robocopy /OFFLOAD leaks too.
/NOCLONE is not supported by that robocopy version:
So this leak looks like a recent and still existing defect.
(Sorry for a delay, fighting with OS updates/installation took me a while.)
Best regards,
Alexander
