Manfred Spraul wrote: > Jeroen Ruigrok/asmodai wrote: > > >-On [20030908 23:52], Peter Eisentraut ([EMAIL PROTECTED]) wrote: > > > > > >>Why would FreeBSD have a "library of thread-safe libc functions" (libc_r) > >>if the functions weren't thread-safe? I think the test is faulty. > >> > >> > A thread-safe library has a per-thread errno value (i.e. errno is a > #define to a function call), thread-safe io buffers for stdio, etc. Some > of these changes cause a noticable overhead, thus a seperate library for > those users who want to avoid that overhead. > > Reentrancy is independant from _r: If you look at the prototype of > gethostbyname(), it's just not possible to make that thread safe with > reasonable effort - the C library would have to keep one buffer per > thread around.
See the top of src/port/thread.c --- that's exactly what is does (keep one buffer per thread around). * Threading sometimes requires specially-named versions of functions * that return data in static buffers, like strerror_r() instead of * strerror(). Other operating systems use pthread_setspecific() * and pthread_getspecific() internally to allow standard library * functions to return static data to threaded applications. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
