Cgroup v2 support is now present in the latest release of Isolate. See also #1257.

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All modified and coverable lines are covered by tests ✅

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@@            Coverage Diff             @@
##           master    #1222      +/-   ##
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+ Coverage   69.39%   69.55%   +0.15%     
==========================================
  Files         328      328              
  Lines       26201    26201              
==========================================
+ Hits        18182    18223      +41     
+ Misses       8019     7978      -41     

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To clarify, until this gets merged we should still use the kernel flags as detailed in ioi/isolate#35, correct?

At the moment, using v1.4.rc1, I get the following cgroups-related error:

Failed to create control group /sys/fs/cgroup/memory/box-0/: No such file or directory
Traceback (most recent call last):
  File "/home/cms/cms_venv/bin/cmsMake", line 11, in <module>
    load_entry_point('cms==1.4rc1', 'console_scripts', 'cmsMake')()
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cmstaskenv/cmsMake.py", line 755, in main
    assume=assume)
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cmstaskenv/cmsMake.py", line 692, in execute_multiple_targets
    already_executed, debug=debug, assume=assume)
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cmstaskenv/cmsMake.py", line 682, in execute_target
    action(assume=assume)
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cmstaskenv/cmsMake.py", line 269, in test_src
    assume=assume)
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cmstaskenv/Test.py", line 163, in test_testcases
    tasktype.evaluate(job, file_cacher)
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cms/grading/tasktypes/Batch.py", line 290, in evaluate
    sandbox = create_sandbox(file_cacher, name="evaluate")
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cms/grading/tasktypes/util.py", line 71, in create_sandbox
    sandbox = Sandbox(file_cacher, name=name)
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cms/grading/Sandbox.py", line 944, in __init__
    self.initialize_isolate()
  File "/home/cms/cms_venv/lib/python3.6/site-packages/cms-1.4rc1-py3.6.egg/cms/grading/Sandbox.py", line 1420, in initialize_isolate
    "(error %d)" % (pretty_print_cmdline(init_cmd), ret))
cms.grading.Sandbox.SandboxInterfaceException: Failed to initialize sandbox with command: isolate --cg --box-id=0 --init (error 2)

UPDATE: After discussion with @veluca93, we decided to create a local ./config/isolate.conf.sample file (alongside the cms.conf.sample, nginx.conf.sample, etc) with cg_root overridden to /sys/fs/cgroup, and install that file as part of the prerequisites.py install step instead of the default isolate config file.

Maybe I am misunderstanding something, but as per https://systemd.io/CGROUP_DELEGATION/ the root cgroup shouldn't not be touched by anything other than systemd. So even if it appears to work now, using /sys/fs/cgroup seems to go against systemd's expectations.

@gollux ?

I completely agree that overriding cg_root on systems with systemd is wrong because it's in direct violation of systemd's cgroup delegation principles. Please don't do that.

I would very much like CMS to stop installing isolate. It's a separate project and users should run its own installation mechanism. I would like to provide Debian/Ubuntu packages of Isolate, which install the systemd service following Debian conventions. I welcome other people to contribute packaging for their favorite distributions.

I would like to provide Debian/Ubuntu packages of Isolate, which install the systemd service following Debian conventions. I welcome other people to contribute packaging for their favorite distributions.

Thank you @gollux that would be very helpful. Let me know how you plan to provide the .deb file and we will then integrate it as part of CMS's installation.

A good way I guess would be to use Github "Releases" in https://github.com/ioi/isolate/releases and upload the .deb as an artifact of each release, what do you think?