Initially reported at https://chatlogs.metabrainz.org/brainzbot/metabrainz/msg/4528331/

We have noticed some of the indexing processes hanging every now and then, requiring a kill / restart. Currently, we are restarting SIR before fetching replication packets and it seems to be working fine.

[...] It's possibly environmental - resource exhaustion.

[...] I think the issue is here: https://github.com/metabrainz/sir/blob/v1.0.2/sir/indexing.py#L112-L172