test_export_data_command.sh CI script hung

[anoadragon453]

I had an instance of the test_export_data_command script running for 6h in CI before eventually being timed out: https://github.com/matrix-org/synapse/runs/4010916318?check_suite_focus=true

It looks like the script got to this line before simply stopping:

synapse/.ci/scripts/test_export_data_command.sh

Line 24 in c7a5e49

scripts/update_synapse_database --database-config .ci/sqlite-config.yaml --run-background-updates

Perhaps a case of Synapse failing to shut down properly?

Should we place a smaller timeout on (a part of) this script - which would fail the test, but without burning so much CI time - in the short term?

[squahtx]

It seems to be fallout from #11177. We might need to do something to shut down the thread pool

[squahtx]

I'll PR a fix