Merge pull request #1325 from alblue/master

Author: swift-ci

CoreFoundation/Base.subproj/CFPlatform.c

@@ -582,11 +582,16 @@ CF_PRIVATE void __CFFinalizeWindowsThreadData() {
 #endif
 
 static pthread_key_t __CFTSDIndexKey;
+static pthread_once_t __CFTSDIndexKey_once = PTHREAD_ONCE_INIT;
 
-CF_PRIVATE void __CFTSDInitialize() {
+CF_PRIVATE void __CFTSDInitializeOnce() {
     (void)pthread_key_create(&__CFTSDIndexKey, __CFTSDFinalize);
 }
 
+CF_PRIVATE void __CFTSDInitialize() {
+    (void)pthread_once(&__CFTSDIndexKey_once, __CFTSDInitializeOnce);
+}
+
 static void __CFTSDSetSpecific(void *arg) {
 #if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI
     pthread_setspecific(__CFTSDIndexKey, arg);