Although the Mac OSX pthreads implementation complies with the POSIX standard, it does not include all the pthreads and associated functionality available on Linux. Functions that are not implemented are available as stubs that return error codes. This can be problematical when porting code that does not rigorously check error return codes, as the code will compile and run but may not function as expected. Here are some specific features of Linux pthreads that are not available on Mac OSX as of the Tiger release: