Log blackhole blocks

rts/Messages.c

@@ -15,6 +15,7 @@
 #include "RaiseAsync.h"
 #include "sm/Storage.h"
 #include "CloneStack.h"
+#include "Libdw.h"
 
 /* ----------------------------------------------------------------------------
    Send a message to another Capability
@@ -205,6 +206,16 @@ uint32_t messageBlackHole(Capability *cap, MessageBlackHole *msg)
 
     if (info == &stg_TSO_info)
     {
+
+#if USE_LIBDW
+     fprintf(stderr, "\n");
+     fprintf(stderr, "Stack trace:\n");
+     LibdwSession *session = libdwInit();
+     Backtrace *bt = libdwGetBacktrace(session);
+     libdwPrintBacktrace(session, stderr, bt);
+     backtraceFree(bt);
+     libdwFree(session);
+#endif
         StgTSO *owner = (StgTSO*)p;
 
 #if defined(THREADED_RTS)