libpq and multi-threading

I have a question about libpq and multi-threading.

In the PostgreSQL documentation (https://www.postgresql.org/docs/15/libpq-threading.html) it says that results can be passed around freely between threads. However, when I try to read the result from the parent thread, the program crashes with a segmentation fault.

I have already tried to set the PostgreSQL 'dynamic_shared_memory_type' configuration option to 'mmap', but this does not help.

Am I doing something wrong? How can I make libpq use mmap to allocate memory that can be read from the parent thread?

Best regards,

Mischa Baars.