Questions

[heddn]

What version of migrate_source_csv was this developed for? Is it for v2 or v3?

Is there any chance that some of this could be split up, generalized and pushed back up to migrate_tools? I'd much rather collaborate then splinter the project namespace for tools like this.

[heddn]

v3 of migrate source csv does file streaming from the csv because of its dependency on league/csv. So I wonder if there are some memory management features from it which help. Of course if this is already running v3, then there still more work to be done. And perhaps breaking up the drush command into chunks is a good path forward.