Feature, enhancement: glibc implementation of `pthread_gettid_np` function Reason: Previously, there was no direct way to obtain the Linux task/thread ID (TID) from a glibc `pthread_t` handle. The `pthread_gettid_np` function declared in `<pthread.h>` (if `_GNU_SOURCE` is in effect) provides the TID value directly. Result: Applications that need to use functions such as `sched_setattr` that expect a TID can do if they first obtain the TID from a `pthread_t` handle.