7 files changed, 250 insertions, 133 deletions

diff --git a/CHANGES b/CHANGES
index bc0368a..58b6061 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3,12 +3,14 @@ CHANGES:
 
 CHANGE X:
 
-CHANGE 29 BGe 21-Feb-2011
-    Make the number of internal keeper states selectable by an optional parameter passed to require.
+CHANGE 29 BGe 1-Mar-2011
+    fixed potential crash at application shutdown when calling lua_close() on a killed thread's VM.
+    exposed cancel_test() in the lanes to enable manual testing for cancellation requests.
+    removed kludgy {globals={threadName}} support, replaced with a new function set_debug_threadname().
 
 CHANGE 28 BGe 18-Feb-2011
-    Moved keeper-related code in a separate source file
-    keeper.lua is now embedded in text form instead of bytecode to improve LuaJIT2-compatibility
+    - moved keeper-related code in a separate source file
+    - keeper.lua is now embedded in text form instead of bytecode to improve LuaJIT2-compatibility
 
 CHANGE 27 BGe 17-Feb-2011
     - we know Lanes is loaded in the master state, so we don't force it
@@ -29,7 +31,7 @@ CHANGE 26 BGe 14-Feb-2011:
     inter-state data copy for unsupported types
 
 CHANGE 25 BGe 12-Feb-2011:
-    Changed idfunc signature and contract to clarify the fact it is not lua-callable
+    Changed idfunc signature and contract to clarify that fact it is not lua-callable
     and to be able to require the module it was exported from in the target lanes
 
 CHANGE 24 DPtr 25-Jan-2011:
@@ -59,7 +61,7 @@ CHANGE 19 BGe 2-Dec-2010:
 
 CHANGE 18 BGe 6-Oct-2010:
     Fixed 'memory leak' in some situations where a free running lane is collected before application shutdown
-    A bit of code cleanup
+        A bit of code cleanup
 
 CHANGE 17 BGe 21-Sept-2010:
     Fixed stupid compilation errors.
diff --git a/Makefile b/Makefile
index f27404a..ddd8675 100644
--- a/Makefile
+++ b/Makefile
@@ -84,6 +84,7 @@ test:
         $(MAKE) fibonacci
         $(MAKE) recursive
         $(MAKE) func_is_string
+        $(MAKE) atexit
 
 basic: tests/basic.lua $(_TARGET_SO)
         $(_PREFIX) $(LUA) $<
@@ -154,6 +155,9 @@ appendud: tests/appendud.lua $(_TARGET_SO)
 func_is_string: tests/func_is_string.lua $(_TARGET_SO)
         $(_PREFIX) $(LUA) $<
 
+atexit: tests/atexit.lua $(_TARGET_SO)
+        $(_PREFIX) $(LUA) $<
+
 #---
 perftest-plain: tests/perftest.lua $(_TARGET_SO)
         $(MAKE) _perftest ARGS="$< $(N) -plain"
diff --git a/docs/index.html b/docs/index.html
index 3d2ecf2..ba25515 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -56,7 +56,7 @@
 
 <p><br/><font size="-1"><i>Copyright &copy; 2007-11 Asko Kauppi. All rights reserved.</i>
     <br>Lua Lanes is published under the same <A HREF="http://en.wikipedia.org/wiki/MIT_License">MIT license</A> as Lua 5.1.
-    </p><p>This document was revised on 21-Feb-11, and applies to version 2.1.0.
+    </p><p>This document was revised on 1-Mar-11, and applies to version 2.1.0.
 </font></p>
 
 </center>
@@ -243,6 +243,7 @@ also in the new lanes.
     <tt>:receive()</tt> or <tt>:send()</tt> call.
     With this option, one can set cancellation check to occur every <tt>N</tt>
     Lua statements. The value <tt>true</tt> uses a default value (100).
+    It is also possible to manually test for cancel requests with <tt>cancel_test()</tt>.
     </td></tr>
 
     <tr valign=top><td/><td>
@@ -250,20 +251,21 @@ also in the new lanes.
     <td>
     Sets the globals table for the launched threads. This can be used for giving
     them constants.
-    </p><p>
+    <br>
     The global values of different lanes are in no manner connected;
-    modifying one will only affect the particular lane. Settings the variable 'threadName' in this table makes VS display the sent name instead of the normal thread name while debugging.
+    modifying one will only affect the particular lane.
     </td></tr>
 
     <tr valign=top><td width=40><td>
         <code>.priority</code> <br/><nobr>-2..+2</nobr></td>
         <td>The priority of lanes generated. -2 is lowest, +2 is highest.
-        <p>
+        <br>
     Implementation and dependability of priorities varies
     by platform. Especially Linux kernel 2.6 is not supporting priorities in user mode.
     </td></tr>
   </table>
-
+  <p>Each lane also gets a function <tt>set_debug_threadname()</tt> that it can use anytime to do as the name says.
+Supported debuggers are Microsoft Visual Studio (for the C side) and Decoda (for the Lua side).
 </p>
 
 <h3>Free running lanes</h3>
@@ -374,10 +376,15 @@ that id over a Linda once that thread is done (as the last thing you do).
 <h2 id="cancelling">Cancelling</h2>
 
 <table border=1 bgcolor="#E0E0FF" cellpadding=10><tr><td>
-    <code>bool= lane_h:cancel( [timeout_secs=0.0,] [force_kill_bool=false] )</code>
+    <code>bool= lane_h:cancel( [timeout_secs=0.0,] [force_kill_bool=false] )
+    <br/>
+    <br/>
+      <code>
+     bool= cancel_test()
+      </code>
 </table>
 
-<p>Sends a cancellation request to the lane. If <tt>timeout_secs</tt> is non-zero, waits
+<p><tt>cancel()</tt>sends a cancellation request to the lane. If <tt>timeout_secs</tt> is non-zero, waits
 for the request to be processed, or a timeout to occur.
 Returns <tt>true</tt> if the lane was already done (in <tt>"done"</tt>, <tt>"error"</tt> or <tt>"cancelled"</tt> status)
 or if the cancellation was fruitful within timeout period.
@@ -387,8 +394,9 @@ OS thread running the lane is forcefully killed. This means no GC, and should
 generally be the last resort.
 </p>
 <p>Cancellation is tested <u>before</u> going to sleep in <tt>receive()</tt> or <tt>send()</tt> calls
-and after executing <tt>cancelstep</tt> Lua statements. A currently pending <tt>receive</tt>
-or <tt>send</tt> call is currently not awakened, and may be a reason for a non-detected cancel.
+and after executing <tt>cancelstep</tt> Lua statements. A currently pending <tt>receive()</tt>
+or <tt>send()</tt> call is currently not awakened, and may be a reason for a non-detected cancel.
+It is also possible to manually test for cancel requests with <tt>cancel_test()</tt>.
 </p>
 
 
@@ -799,7 +807,7 @@ can be used for custom userdata as well. Here's what to do.
 </p>
 <ol>
     <li>Provide an <i>identity function</i> for your userdata, in C. This function is
-      used for creation and deletion of your deep userdata (the shared resource),
+used for creation and deletion of your deep userdata (the shared resource),
       and for making metatables for the state-specific proxies for accessing it. The
       prototype is
       <table border="1" bgcolor="#E0E0FF" cellpadding="10">
@@ -817,12 +825,12 @@ can be used for custom userdata as well. Here's what to do.
       <tt>"delete"</tt>: receives this same pointer on the stack, and should cleanup the object.</li>
     <li>
       <tt>"metatable"</tt>: should build a metatable for the object. Don't cache the metatable
-      yourself, Lanes takes care of it ("metatable" should only be invoked once).</li>
+yourself, Lanes takes care of it ("metatable" should only be invoked once).</li>
       <li>
         <tt>"module"</tt>: is the name of the module that exports the idfunc,
-        to be pushed on the stack as a string. It is necessary so that Lanes can require it in
-        any Lane and keeper state that receives a userdata. This is to prevent crashes in situations
-        where the module could be unloaded while the idfunc pointer is still held.</li>
+to be pushed on the stack as a string. It is necessary so that Lanes can require it in
+any Lane and keeper state that receives a userdata. This is to prevent crashes in situations
+where the module could be unloaded while the idfunc pointer is still held.</li>
 </ul>
 Take a look at <tt>linda_id</tt> in <tt>lanes.c</tt>.
     </li>
@@ -917,10 +925,10 @@ Here are some things one should consider, if best performance is vital:
     merged into one main timer state (see <tt>timer.lua</tt>); no OS side
     timers are utilized.
     </li>
-    <li>Lindas are hashed to a number of "keeper states", which are a locking entity.
-    If you are using a lot of Linda objects, it may be useful to try having more of
-    these keeper states. By default, only one is used but this is an implementation detail.
-    It is possible to <tt>require( "lanes", N)</tt> to use more keeper states.
+    <li>Lindas are hashed to a fixed number of "keeper states", which are a locking entity.
+    If you are using a lot of Linda objects,
+    it may be useful to try having more of these keeper states. By default,
+    only one is used (see <tt>KEEPER_STATES_N</tt>), but this is an implementation detail.
     </li>
 </ul>
 </p>
@@ -952,31 +960,15 @@ its actual value.
 <h2 id="changes">Change log</h2>
 
 <p>
-Feb-2011 (2.1.0)
+
+Mar-2011 (2.1.0)
 <ul>
-  <li>Added an auto-require mechanism to ensure any deep userdata transiting in a lane causes its parent module to be required in that lane
-  <ul>
-    <li>Changed idfunc signature and contract to clarify the fact it is not lua-callable and to be able to require the module it was exported from in the target lanes</li>
-    <li>When a deep userdata idfunc requests a module to be required, manually check that it is not loaded before requiring it instead of relying on the require function's loop detection feature</li>
-    <li>When a module must be required, raise an error if the 'require' function is not found in the target state</li>
-    <li>We know Lanes is loaded in the master state, so we don't force it to be required in every lane too when a linda deep userdata is copied</li>
-  </ul>
-  </li>
-  <li>Fixed application hang-up because keeper state was not released in case of errors thrown by inter-state data copy for unsupported types</li>
-  <li>Refactor lane proxy implementation: it is now a full userdata instead of a table, and its methods are implemented in C instead of Lua
-    <ul>
-      <li>its metatable is no longer accessible</li>
-      <li>writing to the proxy raises an error</li>
-      <li>it is no longer possible to overwrite its join() and cancel() methods</li>
-    </ul>
-  </li>
-  <li>Moved keeper-related code in a separate source file</li>
-  <li>keeper.lua is now embedded in text form instead of bytecode to improve LuaJIT2-compatibility</li>
-  <li>Make the number of internal keeper states selctable by an optional parameter passed to require.</li>
+  <li>fixed potential crash at application shutdown when calling lua_close() on a killed thread's VM.</li>
+  <li>exposed cancel_test() in the lanes to enable manual testing for cancellation requests.</li>
+  <li>removed kludgy {globals={threadName}} support, replaced with a new function set_debug_threadname().</li>
 </ul>
-
 Feb-2011 (2.0.11):
-<ul>
+  <ul>
   <li>Fixed bug where reference to Linda object was dropped for a short time (crashing if GC was run during that time).</li>
   <li>Changed the atexit code to trip the timer thread's write signal.</li>
   <li>Changed lanes.c to export functions as a module rather than writing them directly to the globals table.</li>
diff --git a/src/keeper.c b/src/keeper.c
index f89c638..01e8880 100644
--- a/src/keeper.c
+++ b/src/keeper.c
@@ -94,6 +94,12 @@ char const *init_keepers( int const _nbKeepers)
                 if (!L)
                         return "out of memory";
 
+                // to see VM name in Decoda debugger
+                lua_pushliteral( L, "Keeper #");
+                lua_pushinteger( L, i + 1);
+                lua_concat( L, 2);
+                lua_setglobal( L, "decoda_name");
+
                 luaG_openlibs( L, "io,table,package" );     // 'io' for debugging messages, package because we need to require modules exporting idfuncs
                 serialize_require( L);
 
diff --git a/src/lanes.c b/src/lanes.c
index 8b62532..e5a2987 100644
--- a/src/lanes.c
+++ b/src/lanes.c
@@ -119,8 +119,6 @@ struct s_lane {
         //
         // M: sub-thread OS thread
         // S: not used
-   
-   char threadName[64]; //Optional, for debugging and such. owerflowable by a strcpy.
 
         lua_State *L;
         //
@@ -132,6 +130,10 @@ struct s_lane {
         // M: sets to PENDING (before launching)
         // S: updates -> RUNNING/WAITING -> DONE/ERROR_ST/CANCELLED
 
+        volatile SIGNAL_T waiting_on;
+        //
+        // When status is WAITING, points on the linda's signal the thread waits on, else NULL
+
         volatile bool_t cancel_request;
         //
         // M: sets to FALSE, flags TRUE for cancel request
@@ -333,17 +335,21 @@ LUAG_FUNC( linda_send)
                                 {
                                         prev_status = s->status;
                                         s->status = WAITING;
+                                        ASSERT_L( s->waiting_on == NULL);
+                                        s->waiting_on = &linda->read_happened;
                                 }
                                 if( !SIGNAL_WAIT( &linda->read_happened, &K->lock_, timeout))
                                 {
                                         if( s)
                                         {
+                                                s->waiting_on = NULL;
                                                 s->status = prev_status;
                                         }
                                         break;
                                 }
                                 if( s)
                                 {
+                                        s->waiting_on = NULL;
                                         s->status = prev_status;
                                 }
                         }
@@ -450,17 +456,21 @@ LUAG_FUNC( linda_receive)
                                 {
                                         prev_status = s->status;
                                         s->status = WAITING;
+                                        ASSERT_L( s->waiting_on == NULL);
+                                        s->waiting_on = &linda->write_happened;
                                 }
                                 if( !SIGNAL_WAIT( &linda->write_happened, &K->lock_, timeout))
                                 {
                                         if( s)
                                         {
+                                                s->waiting_on = NULL;
                                                 s->status = prev_status;
                                         }
                                         break;
                                 }
                                 if( s)
                                 {
+                                        s->waiting_on = NULL;
                                         s->status = prev_status;
                                 }
                         }
@@ -870,28 +880,33 @@ volatile DEEP_PRELUDE *timer_deep;  // = NULL
 /*
 * Process end; cancel any still free-running threads
 */
-static void selfdestruct_atexit( void ) {
-
+static void selfdestruct_atexit( void )
+{
     if (selfdestruct_first == SELFDESTRUCT_END) return;    // no free-running threads
 
-    // Signal _all_ still running threads to exit
+    // Signal _all_ still running threads to exit (including the timer thread)
     //
     MUTEX_LOCK( &selfdestruct_cs );
     {
         struct s_lane *s= selfdestruct_first;
-        while( s != SELFDESTRUCT_END ) {
-            s->cancel_request= TRUE;
-            s= s->selfdestruct_next;
+        while( s != SELFDESTRUCT_END )
+        {
+            // attempt a regular unforced cancel with a small timeout
+            bool_t cancelled = thread_cancel( s, 0.0001, FALSE);
+            // if we failed, and we know the thread is waiting on a linda
+            if( cancelled == FALSE && s->status == WAITING && s->waiting_on != NULL)
+            {
+                // signal the linda the wake up the thread so that it can react to the cancel query
+                // let us hope we never land here with a pointer on a linda that has been destroyed...
+                SIGNAL_T waiting_on = s->waiting_on;
+                s->waiting_on = NULL;
+                SIGNAL_ALL( waiting_on);
+            }
+            s = s->selfdestruct_next;
         }
     }
     MUTEX_UNLOCK( &selfdestruct_cs );
 
-    // Tell the timer thread to check it's cancel request
-    {
-        struct s_Linda *td = timer_deep->deep;
-        SIGNAL_ALL( &td->write_happened);
-    }
-
     // When noticing their cancel, the lanes will remove themselves from
     // the selfdestruct chain.
 
@@ -914,15 +929,37 @@ static void selfdestruct_atexit( void ) {
     //  -- AKa 25-Oct-2008
     //
     #ifndef ATEXIT_WAIT_SECS
-    # define ATEXIT_WAIT_SECS (0.1)
+    # define ATEXIT_WAIT_SECS (0.25)
     #endif
     {
         double t_until= now_secs() + ATEXIT_WAIT_SECS;
-    
-        while( selfdestruct_first != SELFDESTRUCT_END ) {
+
+        while( selfdestruct_first != SELFDESTRUCT_END )
+        {
             YIELD();    // give threads time to act on their cancel
-            
-            if (now_secs() >= t_until) break;
+            {
+                // count the number of cancelled thread that didn't have the time to act yet
+                int n = 0;
+                double t_now = 0.0;
+                MUTEX_LOCK( &selfdestruct_cs );
+                {
+                    struct s_lane *s = selfdestruct_first;
+                    while( s != SELFDESTRUCT_END)
+                    {
+                        if( s->cancel_request)
+                            ++ n;
+                        s = s->selfdestruct_next;
+                    }
+                }
+                MUTEX_UNLOCK( &selfdestruct_cs );
+                // if timeout elapsed, or we know all threads have acted, stop waiting
+                t_now = now_secs();
+                if( n == 0 || ( t_now >= t_until))
+                {
+                    DEBUGEXEC(fprintf( stderr, "%d uncancelled lane(s) remain after waiting %fs at process end.\n", n, ATEXIT_WAIT_SECS - (t_until - t_now)));
+                    break;
+                }
+            }
         }
     }
 #endif
@@ -951,18 +988,21 @@ static void selfdestruct_atexit( void ) {
         //
         DEBUGEXEC(fprintf( stderr, "Left %d lane(s) with cancel request at process end.\n", n ));
 #else
+        // first thing we did was to raise the linda signals the threads were waiting on (if any)
+        // therefore, any well-behaved thread should be in CANCELLED state
+        // these are not running, and the state can be closed
         n=0;
         MUTEX_LOCK( &selfdestruct_cs );
         {
             struct s_lane *s= selfdestruct_first;
-            while( s != SELFDESTRUCT_END ) {
+            while( s != SELFDESTRUCT_END)
+            {
                 struct s_lane *next_s= s->selfdestruct_next;
                 s->selfdestruct_next= NULL;     // detach from selfdestruct chain
-
-                THREAD_KILL( &s->thread );
-                lua_close(s->L);
-                free(s);
-                s= next_s;
+                THREAD_KILL( &s->thread);
+                // NO lua_close() in this case because we don't know where execution of the state was interrupted
+                free( s);
+                s = next_s;
                 n++;
             }
             selfdestruct_first= SELFDESTRUCT_END;
@@ -1022,6 +1062,19 @@ static void cancel_hook( lua_State *L, lua_Debug *ar ) {
 
 
 //---
+// bool= cancel_test()
+//
+// Available inside the global namespace of lanes
+// returns a boolean saying if a cancel request is pending
+//
+LUAG_FUNC( cancel_test)
+{
+        bool_t test = cancel_test( L);
+        lua_pushboolean( L, test);
+        return 1;
+}
+
+//---
 // = _single( [cores_uint=1] )
 //
 // Limits the process to use only 'cores' CPU cores. To be used for performance
@@ -1131,12 +1184,12 @@ typedef struct tagTHREADNAME_INFO
 } THREADNAME_INFO;
 #pragma pack(pop)
 
-void SetThreadName( DWORD dwThreadID, char* threadName)
+void SetThreadName( DWORD dwThreadID, char const *_threadName)
 {
    THREADNAME_INFO info;
    Sleep(10);
    info.dwType = 0x1000;
-   info.szName = threadName;
+   info.szName = _threadName;
    info.dwThreadID = dwThreadID;
    info.dwFlags = 0;
 
@@ -1150,6 +1203,22 @@ void SetThreadName( DWORD dwThreadID, char* threadName)
 }
 #endif
 
+LUAG_FUNC( set_debug_threadname)
+{
+        char const *threadName;
+        luaL_checktype( L, -1, LUA_TSTRING);
+        threadName = lua_tostring( L, -1);
+
+#if defined PLATFORM_WIN32  && !defined __GNUC__
+        // to see thead name in Visual Studio C debugger
+        SetThreadName(-1, threadName);
+#endif
+
+        // to see VM name in Decoda debugger Virtual Machine window
+        lua_setglobal( L, "decoda_name");
+
+        return 0;
+}
 
 //---
 #if (defined PLATFORM_WIN32) || (defined PLATFORM_POCKETPC)
@@ -1162,11 +1231,6 @@ void SetThreadName( DWORD dwThreadID, char* threadName)
     int rc, rc2;
     lua_State *L= s->L;
 
- 
-#if defined PLATFORM_WIN32  && !defined __GNUC__
-        SetThreadName(-1, s->threadName);
-#endif
-
    s->status= RUNNING;  // PENDING -> RUNNING
 
     // Tie "set_finalizer()" to the state
@@ -1174,6 +1238,16 @@ void SetThreadName( DWORD dwThreadID, char* threadName)
     lua_pushcfunction( L, LG_set_finalizer );
     lua_setglobal( L, "set_finalizer" );
 
+    // Tie "set_debug_threadname()" to the state
+    //
+    lua_pushcfunction( L, LG_set_debug_threadname);
+    lua_setglobal( L, "set_debug_threadname" );
+
+    // Tie "cancel_test()" to the state
+    //
+    lua_pushcfunction( L, LG_cancel_test);
+    lua_setglobal( L, "cancel_test" );
+
 #ifdef ERROR_FULL_STACK
     STACK_GROW( L, 1 );
     lua_pushcfunction( L, lane_error );
@@ -1240,7 +1314,7 @@ void SetThreadName( DWORD dwThreadID, char* threadName)
         //
         lua_newtable(L);
     }
-
+    s->waiting_on = NULL; // just in case
     if (s->selfdestruct_next != NULL) {
         // We're a free-running thread and no-one's there to clean us up.
         //
@@ -1276,7 +1350,6 @@ void SetThreadName( DWORD dwThreadID, char* threadName)
         MUTEX_UNLOCK( &s->done_lock_ );
     #endif
     }
-
     return 0;   // ignored
 }
 
@@ -1295,7 +1368,6 @@ LUAG_FUNC( thread_new )
         lua_State *L2;
         struct s_lane *s;
         struct s_lane **ud;
-        const char *threadName = 0;
 
         const char *libs= lua_tostring( L, 2 );
         uint_t cs= luaG_optunsigned( L, 3,0);
@@ -1330,10 +1402,7 @@ LUAG_FUNC( thread_new )
                         luaL_error( L, "Expected table, got %s", luaG_typename(L,glob) );
 
                 lua_pushvalue( L, glob );
-                lua_pushstring( L, "threadName");
-                lua_gettable( L, -2);
-                threadName = lua_tostring( L, -1);
-                lua_pop( L, 1);
+
                 luaG_inter_move( L, L2, 1);     // moves the table to L2
 
                 // L2 [-1]: table of globals
@@ -1398,11 +1467,9 @@ LUAG_FUNC( thread_new )
         //memset( s, 0, sizeof(struct s_lane) );
         s->L= L2;
         s->status= PENDING;
+        s->waiting_on = NULL;
         s->cancel_request= FALSE;
 
-        threadName = threadName ? threadName : "<unnamed thread>";
-        strcpy(s->threadName, threadName);
-
 #if !( (defined PLATFORM_WIN32) || (defined PLATFORM_POCKETPC) || (defined PTHREAD_TIMEDJOIN) )
         MUTEX_INIT( &s->done_lock_ );
         SIGNAL_INIT( &s->done_signal_ );
@@ -1484,7 +1551,7 @@ LUAG_FUNC( thread_gc )
 #if 0
                 lua_close( s->L );
                 s->L = 0;
-#else
+#else // 0
                 DEBUGEXEC(fprintf( stderr, "** Joining with a killed thread (needs testing) **" ));
 #if (defined PLATFORM_WIN32) || (defined PLATFORM_POCKETPC) || (defined PTHREAD_TIMEDJOIN)
                 THREAD_WAIT( &s->thread, -1 );
@@ -1492,7 +1559,7 @@ LUAG_FUNC( thread_gc )
                 THREAD_WAIT( &s->thread, &s->done_signal_, &s->done_lock_, &s->status, -1 );
 #endif
                 DEBUGEXEC(fprintf( stderr, "** Joined ok **" ));
-#endif
+#endif // 0
         }
         else if( s->L)
         {
@@ -1529,54 +1596,55 @@ LUAG_FUNC( thread_gc )
 //          managed to cancel it.
 //          false if the cancellation timed out, or a kill was needed.
 //
-LUAG_FUNC( thread_cancel )
+static bool_t thread_cancel( struct s_lane *s, double secs, bool_t force)
 {
-    struct s_lane *s= lua_toLane(L,1);
-    double secs= 0.0;
-    uint_t force_i=2;
-    bool_t force, done= TRUE;
-    
-    if (lua_isnumber(L,2)) {
-        secs= lua_tonumber(L,2);
-        force_i++;
-    } else if (lua_isnil(L,2))
-        force_i++;
-
-    force= lua_toboolean(L,force_i);     // FALSE if nothing there
-    
-    // We can read 's->status' without locks, but not wait for it (if Posix no PTHREAD_TIMEDJOIN)
-    //
-    if (s->status < DONE) {
-        s->cancel_request= TRUE;    // it's now signalled to stop
-
-        done= thread_cancel( s, secs, force );
-    }
-
-    lua_pushboolean( L, done );
-    return 1;
-}
-
-static bool_t thread_cancel( struct s_lane *s, double secs, bool_t force )
-{
-    bool_t done= 
+        bool_t done= TRUE;
+        // We can read 's->status' without locks, but not wait for it (if Posix no PTHREAD_TIMEDJOIN)
+        //
+        if( s->status < DONE)
+        {
+                s->cancel_request = TRUE;    // it's now signalled to stop
+                done= 
 #if (defined PLATFORM_WIN32) || (defined PLATFORM_POCKETPC) || (defined PTHREAD_TIMEDJOIN)
-        THREAD_WAIT( &s->thread, secs );
+                        THREAD_WAIT( &s->thread, secs);
 #else
-        THREAD_WAIT( &s->thread, &s->done_signal_, &s->done_lock_, &s->status, secs );
+                        THREAD_WAIT( &s->thread, &s->done_signal_, &s->done_lock_, &s->status, secs);
 #endif
 
-    if ((!done) && force) {
-        // Killing is asynchronous; we _will_ wait for it to be done at
-        // GC, to make sure the data structure can be released (alternative
-        // would be use of "cancellation cleanup handlers" that at least
-        // PThread seems to have).
-        //
-        THREAD_KILL( &s->thread );
-        s->mstatus= KILLED;     // mark 'gc' to wait for it
-    }
-    return done;
+                if ((!done) && force)
+                {
+                        // Killing is asynchronous; we _will_ wait for it to be done at
+                        // GC, to make sure the data structure can be released (alternative
+                        // would be use of "cancellation cleanup handlers" that at least
+                        // PThread seems to have).
+                        //
+                        THREAD_KILL( &s->thread);
+                        s->mstatus= KILLED;     // mark 'gc' to wait for it
+                }
+        }
+        return done;
 }
 
+LUAG_FUNC( thread_cancel)
+{
+        struct s_lane *s= lua_toLane(L,1);
+        double secs= 0.0;
+        uint_t force_i=2;
+        bool_t force, done= TRUE;
+
+        if (lua_isnumber(L,2)) {
+                secs= lua_tonumber(L,2);
+                force_i++;
+        } else if (lua_isnil(L,2))
+                force_i++;
+
+        force= lua_toboolean(L,force_i);     // FALSE if nothing there
+
+        done = thread_cancel( s, secs, force);
+
+        lua_pushboolean( L, done);
+        return 1;
+}
 
 //---
 // str= thread_status( lane )
diff --git a/src/lanes.lua b/src/lanes.lua
index 78582f9..704559a 100644
--- a/src/lanes.lua
+++ b/src/lanes.lua
@@ -399,8 +399,8 @@ if first_time then
     -- We let the timer lane be a "free running" thread; no handle to it
     -- remains.
     --
-    gen( "io,package", { priority=max_prio, globals={threadName="LanesTimer"} }, function()
-
+    gen( "io,package", { priority=max_prio}, function()
+        set_debugger_threadname( "LanesTimer")
         while true do
             local next_wakeup= check_timers()
 
diff --git a/tests/atexit.lua b/tests/atexit.lua
new file mode 100644
index 0000000..fb4f34a
--- /dev/null
+++ b/tests/atexit.lua
@@ -0,0 +1,45 @@
+require "lanes"
+
+-- create a free-running lane
+
+local linda = lanes.linda()
+
+local f = function( _linda)
+        _linda:receive("oy")
+end
+
+local g = function()
+        local cancelled
+        repeat
+                cancelled = cancel_test()
+        until cancelled
+        print "User cancellation detected!"
+end
+
+local genF = lanes.gen( "", {globals = {threadName = "mylane"}}, f)
+local genG = lanes.gen( "", g)
+
+
+-- launch a good batch of free running lanes
+for i = 1, 10 do
+        -- if i%50 == 0 then print( i) end
+        local h = genF( linda)
+        local status
+        repeat
+                status = h.status
+                --print( status)
+        until status == "waiting"
+
+        -- [[
+        local h = genG()
+        local status
+        repeat
+                status = h.status
+                --print( status)
+        until status == "running"
+        --]]
+end
+
+print "exiting"
+
+-- let process end terminate them and see what happens
\ No newline at end of file