On 18.10.2017 19:56, Branko Čibej wrote:
On 18.10.2017 13:31, Thomas Singer wrote:
Hi,
When performing following steps on my old Linux test machine (with
slow hard disk):
- have a SVN working copy at /home/user/test
- sudo apt install nfs-kernel-server
- add following line to /etc/exports:
/home/user/test *(rw,sync,no_root_squash)
- start the NFS server:
sudo systemctl start nfs-kernel-server.service
- mount the NFS share:
sudo mount localhost:/home/user/test /home/user/test.nfs
and then open /home/user/test.nfs in SmartSVN 9.2 (using SVN 1.9
JavaHL binaries), adding/removing a file is very slow. It boils down
to the call ISVNClient.getChangelists which takes ~8s on the NFS share
(/home/user/test.nfs). First, I thought, it would be caused by the
native-Java overhead calling the call-back ~11,000 times for my
working copy, but when using the working copy directly
(/home/user/test), the method just takes <1s though the ~11,000 times
call-back invocations are still there.
My working copy has no local modifications, no untracked or ignored
files, no changelists.
Is it expected that this method (ISVNClient.getChangelists) is so slow
on a NFS share even if there are no changelists?
I don't know if it's "expected" but I bet that NFS is killing SQLite
performance.
https://www.mail-archive.com/sqlite-users@mailinglists.sqlite.org/msg88989.html
I'm not sure about the reason but the most likely answer, apart from
slow data rate and latency when compared to a local filesystem (which,
in your case on loopback, should not be an issue), is that the OS can't
really use a cache for files on NFS since it has no way to know whether
or not it's valid. With a lot of random-access reads and writes, that
can be a HUGE slowdown, as you found.
Also this:
https://sqlite.org/faq.html#q5
In other words, Subversion working copies on NFS are, and have always
been, a bad idea; not only because of SQLite but also because
Subversion's code itself relies on atomic renames, which NFS does not
provide.
-- Brane
What SVN command (on command line) I should test to get a similar result
as from ISVNClient.getChangelists? I've tried "git status" and it just
needs <1s on the NFS working copy.
--
Best regards,
Thomas Singer
=============
syntevo GmbH
http://www.syntevo.com
http://www.syntevo.com/blog
