--- BDB/xthread.h	2013/12/18 02:52:34	1.13
+++ BDB/xthread.h	2016/02/02 04:07:06	1.14
@@ -168,5 +168,18 @@
 
 #endif
 
+#if __linux && __GNUC__ >= 4 && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 3 && 0 /* also check arch */
+/* __thread has little to no advantage over pthread_* in most configurations, so this is not used */
+# define X_TLS_DECLARE(varname)   __thread void *varname
+# define X_TLS_INIT(varname)      
+# define X_TLS_SET(varname,value) varname = (value)
+# define X_TLS_GET(varname)       varname
+#else
+# define X_TLS_DECLARE(varname)   pthread_key_t varname
+# define X_TLS_INIT(varname)      do { if (pthread_key_create (&(varname), 0)) abort (); } while (0)
+# define X_TLS_SET(varname,value) pthread_setspecific (varname, (value))
+# define X_TLS_GET(varname)       pthread_getspecific (varname)
+#endif
+
 #endif