Can multiple glue crawlers run concurrently?

Each individual Crawler is single threaded, you can't execute the same Crawler more than one at a time. You can have up to 50 crawlers per account as the default limit, and I've had multiple unique crawlers execute at the same time.

https://docs.aws.amazon.com/general/latest/gr/aws_service_limits.html#limits_glue

Crawler setup details are documented here https://docs.aws.amazon.com/glue/latest/dg/crawler-configuration.html How you choose to configure your crawler will depend on what the customer is trying to achieve.

Another thing to note is, you can have a single crawler crawl multiple input data stores. If you had many separate data stores, but they all needed crawling at the same time/frequency, you can have glue either combine them into a single schema (in some circumstances), or multiple schemas (if they're unique).