Hi, I missed this bug report.
I don't have any idea why the tests were failing on a large machine. I've been building and running the autopkgtests for dask.distributed my laptop with 2 cores & 16GB of RAM, and it' hasn't hung for me. I also glanced at the current CI build results and all the runs with 2021.09.1+ds.1-1 seem to be finishing in about 25 minutes both passing and faild tests. I do see the 2h runs with version 2021.08.1+ds.1-1 https://ci.debian.net/packages/d/dask.distributed/ Do you think that's a good enough test to close this bug? Diane
