Trouble installing cylc-8.1.0?

Has anyone run into an issue where installing cylc-flow via conda-forge hangs? I’ve run into this issue on a couple of machines now, where I get the following:

(cylc810) [bcash@cola1 ~]$ conda install -c conda-forge cylc-flow
Collecting package metadata (current_repodata.json): done
Solving environment: failed with initial frozen solve. Retrying with flexible solve.
Solving environment: failed with repodata from current_repodata.json, will retry with next repodata source.
Collecting package metadata (repodata.json): done
Solving environment: /

… and then it just stays in Solving environment until the conda process runs out of memory and/or is killed. Another member of our group tried installing as well, all into new clean environments, without success.

Hi @bencash,

Yes, unfortunately the conda environment solver seems to be really (and increasingly?) slow.

I just tried it myself and quit after waiting 30 mins.

You should use the new fast solver mamba:

$ conda create -n cylc8
$ conda activate cylc8
$ conda install -c conda-forge mamba
$ time mamba install -c conda-forge cylc-flow cylc-uiserver
real    0m50.282s
user    0m17.975s
sys     0m2.604s

$ cylc version

That took 50 seconds including solve, download, and install :tada:

I’ll suggest to the team that we update our installation instructions to include this advice.



I faced the same issue: from /var/log/messages

Jan 27 12:05:37 cylc8dr kernel: Out of memory: Kill process 8340 (conda) score 827 or sacrifice child
Jan 27 12:05:37 cylc8dr kernel: Killed process 8340 (conda), UID 0, total-vm:10735864kB, anon-rss:7044044kB, file-rss:0kB, shmem-rss:0kB

Installing and using Mamba does the trick but installing Mamba required conda-forge be specified as below:

[root@cylc8dr ~]# conda install mamba
Collecting package metadata: done
Solving environment: failed

PackagesNotFoundError: The following packages are not available from current channels:

  • mamba

Current channels:

  • main/linux-64
  • /pkgs/main/noarch
  • /pkgs/free/linux-64
  • /pkgs/free/noarch
  • /pkgs/r/linux-64
  • /pkgs/r/noarch

(removed https to avoid detection as links)

To search for alternate channels that may provide the conda package you’re
looking for, navigate to

and use the search bar at the top of the page.

[root@cylc8dr ~]# conda install -c conda-forge mamba
Collecting package metadata: done
Solving environment: done

Rest of the steps are same.

Thanks very much for that @kumarv !

You’re right. I’ll go back and correct the original post, to avoid confusing feature readers.