Sources Bugzilla – Bug 14304
Provide some parts of librt in libc as well
Last modified: 2013-01-15 14:34:56 UTC
librt links against libpthread, mostly because aio_* are implemented in threads
instead of in the kernel AFAICT. This is unfortunate, because many libraries
would like to use (for example) clock_gettime, but doing so pulls in pthreads.
Now you have no choice but to hit the more expensive thread-safe paths, because
your library can't know whether multiple threads actually exist, only whether
the pthread symbols are non-zero.
The complementary problem also exists for applications that are unthreaded: if
they link against librt, pthread symbols will be non-zero, and any thread-safe
library beneath that app now has to behave thread-safely.
This is especially comic when reading the clock_gettime implementation, which
goes out of its way to work correctly regardless of whether
__pthread_clock_gettime is available.
Ideally it would be possible to provide most of these symbols from libc
directly (presumably versioned so the app requires a sufficiently new libc).
The clock_* function have been moved to libc.
*** This bug has been marked as a duplicate of bug 14743 ***