Hello World with Threads - Threading and Concurrency pt 1b

In part 1b of the multi-threading series, we write our first multi-threaded program using the POSIX threads library. All code for this series can be found here: https://gist.github.com/exbotanical/e58dfbf9676fee0014b304c1f111e904 Don't forget to LIKE and SUBSCRIBE for more deep dive videos like this one! Errata: - At 4:02 I mention there are pthread APIs for modifying thread attributes. I should clarify these are for modifying the `pthread_attr_t` object and NOT `pthread_t` (which is the thread id).