2 files changed, 15 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog
index 7f9dc4bdae..7437ffe63a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun May  1 01:06:24 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* thread.c (rb_thread_select): release GVL while waiting select().
+
 Sat Apr 30 23:10:15 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* win32/win32.c (rb_w32_fdcopy): New. This can copy even though
diff --git a/thread.c b/thread.c
index 53e1a4ed95..dd40be0ece 100644
--- a/thread.c
+++ b/thread.c
@@ -2672,7 +2672,17 @@ rb_thread_select(int max, fd_set * read, fd_set * write, fd_set * except,
 	return 0;
     }
     else {
-	return select(max, read, write, except, timeout);
+	int lerrno;
+	int result;
+
+	BLOCKING_REGION({
+		result = select(max, read, write, except, timeout);
+		if (result < 0)
+		    lerrno = errno;
+	    }, ubf_select, GET_THREAD());
+	errno = lerrno;
+
+	return result;
     }
 }