curb.h

git diff ext/curb.h 
diff --git a/ext/curb.h b/ext/curb.h
index c40a5a0..0c04c63 100644
--- a/ext/curb.h
+++ b/ext/curb.h
@@ -42,6 +42,18 @@
   #define RHASH_LEN(hash) RHASH(hash)->tbl->num_entries
 #endif
 
+#ifdef HAVE_RUBY_THREAD_BLOCKING_REGION
+  struct rb_blocking_region_buffer *rb_thread_blocking_region_begin(void);
+  void rb_thread_blocking_region_end(struct rb_blocking_region_buffer *region);
+  #define RB_UNLOCK_BEGIN() do {struct rb_blocking_region_buffer *__curb__lock = rb_thread_blocking_region_begin();
+  #define RB_UNLOCK_END()  rb_thread_blocking_region_end(__curb__lock); } while(0)
+  #define RB_SELECT select
+#else
+  #define RB_UNLOCK_BEGIN()
+  #define RB_UNLOCK_END()
+  #define RB_SELECT rb_thread_select
+#endif
+
 extern VALUE mCurl;
 
 extern void Init_curb_core();

curb_multi.c

git diff ext/curb_multi.c 
diff --git a/ext/curb_multi.c b/ext/curb_multi.c
index 0306d30..cd9276a 100644
--- a/ext/curb_multi.c
+++ b/ext/curb_multi.c
@@ -161,7 +161,9 @@ static VALUE ruby_curl_multi_add(VALUE self, VALUE easy) {
 
   rbcm->active++;
   if (mcode == CURLM_CALL_MULTI_PERFORM) {
-    curl_multi_perform(rbcm->handle, &(rbcm->running));
+//  RB_UNLOCK_BEGIN();
+    mcode = curl_multi_perform(rbcm->handle,&(rbcm->running));
+//  RB_UNLOCK_END();
   }
 
   rb_hash_aset( rbcm->requests, easy, easy );
@@ -281,9 +283,11 @@ static void rb_curl_multi_read_info(VALUE self, CURLM *multi_handle) {
 static void rb_curl_multi_run(VALUE self, CURLM *multi_handle, int *still_running) {
   CURLMcode mcode;
 
+//  RB_UNLOCK_BEGIN();
   do {
     mcode = curl_multi_perform(multi_handle, still_running);
   } while (mcode == CURLM_CALL_MULTI_PERFORM);
+//  RB_UNLOCK_END();
 
   if (mcode != CURLM_OK) {
     raise_curl_multi_error_exception(mcode);
@@ -358,7 +362,10 @@ static VALUE ruby_curl_multi_perform(VALUE self) {
     tv.tv_sec = timeout / 1000;
     tv.tv_usec = (timeout * 1000) % 1000000;
 
-    rc = rb_thread_select(maxfd+1, &fdread, &fdwrite, &fdexcep, &tv);
+    RB_UNLOCK_BEGIN();
+    rc = RB_SELECT(maxfd+1, &fdread, &fdwrite, &fdexcep, &tv);
+    RB_UNLOCK_END();
+
     if (rc < 0) {
       rb_raise(rb_eRuntimeError, "select(): %s", strerror(errno));
     }