------- Additional Comments From qrczak at knm dot org dot pl 2005-02-24 22:37 ------- > By your definition of MT-safe, almost no function is MT-safe. Is 'strchr' > MT-safe if you call it on a string while another function might modify that > string? No, so lets put automatic locks around 'strchr' and any function that > might modify a string.
The difference is that almost all uses of strchr are done on data which is not shared between threads, while many static local initializers are used on objects which are accessed from multiple threads (when multiple threads are used at all). By your reasoning malloc should be unsafe to use from multiple threads if the user did not explicitly put a lock around it, because it modifies shared data (the heap). And errno should not be automatically made thread-local, because it hurts performance in case thread-locality is not needed. After all, "POSIX puts the responsibility fully on the application programmer to place locks where there might be concurrent access. In exchange for this effort, the programmer gets the performance benefit of there not being locks when they are not needed". Right? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20099
