diff --git a/doc/lua-api/index.rst b/doc/lua-api/index.rst
index adeec112f..b6b9809e8 100644
--- a/doc/lua-api/index.rst
+++ b/doc/lua-api/index.rst
@@ -201,6 +201,16 @@ Core class
   :see: :js:attr:`core.proxies`
   :see: :js:attr:`core.backends`
 
+.. js:attribute:: core.thread
+
+  **context**: task, action, sample-fetch, converter, applet
+
+  This variable contains the executing thread number starting at 1. 0 is a
+  special case for the common lua context. So, if thread is 0, Lua scope is
+  shared by all threads, otherwise the scope is dedicated to a single thread.
+  A program which needs to execute some parts exactly once regardless of the
+  number of threads can check that core.thread is 0 or 1.
+
 .. js:function:: core.log(loglevel, msg)
 
   **context**: body, init, task, action, sample-fetch, converter
diff --git a/src/hlua.c b/src/hlua.c
index 34e7403cf..6153ab769 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -8397,11 +8397,11 @@ static void *hlua_alloc(void *ud, void *ptr, size_t osize, size_t nsize)
 	return ptr;
 }
 
-/* Ithis function can fail with an abort() due to an Lua critical error.
+/* This function can fail with an abort() due to a Lua critical error.
  * We are in the initialisation process of HAProxy, this abort() is
  * tolerated.
  */
-lua_State *hlua_init_state(void)
+lua_State *hlua_init_state(int thread_num)
 {
 	int i;
 	int idx;
@@ -8468,6 +8468,9 @@ lua_State *hlua_init_state(void)
 	/* This table entry is the object "core" base. */
 	lua_newtable(L);
 
+	/* set the thread id */
+	hlua_class_const_int(L, "thread", thread_num);
+
 	/* Push the loglevel constants. */
 	for (i = 0; i < NB_LOG_LEVELS; i++)
 		hlua_class_const_int(L, log_levels[i], i);
@@ -8993,7 +8996,7 @@ lua_State *hlua_init_state(void)
 }
 
 void hlua_init(void) {
-	gL.T = hlua_init_state();
+	gL.T = hlua_init_state(0);
 }
 
 static void hlua_deinit()