In the example I noticed a PREPARE block in addition to the well known BEGIN and END blocks. After a few minutes of searching it appears to be frawk specific:

In the example I noticed a PREPARE block in addition to the well known BEGIN and END blocks. After a few minutes of searching it appears to be frawk specific: https://github.com/ezrosent/frawk/blob/master/info/parallelism.md#aggregations https://github.com/ezrosent/frawk/blob/master/info/paralleli... "Because the repeated map references are both annoying to write and inefficient to execute, frawk has a PREPARE block which executes in the worker threads at the end of its input"