Control when large file sets run in parallel

Goal: Understand and tune mq’s automatic parallel processing for batches of many files, so a big run doesn’t stall on I/O one file at a time.

Prerequisites: None.

Query

By default, mq automatically switches to parallel processing once a run covers more than 10 files — no flag needed:

$ mq '.h1' docs/**/*.md

Use -P <n> to change that threshold — e.g. force parallel mode even for a small batch while testing:

$ mq -P 1 '.h1' docs/**/*.md

Or raise it, to keep small-to-medium batches sequential (useful if the query has ordering side effects):

$ mq -P 50 '.h1' docs/**/*.md

-P is a threshold (files to process before switching to parallel), not a worker count — it doesn’t limit how many files run concurrently.
Output order across files is not guaranteed once parallel processing kicks in — if order matters, raise the threshold above your file count, or sort downstream.