From d350869d104f627ca126c2bdc739355f19697246 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Wed, 15 May 2013 09:15:11 -0600
Subject: [PATCH] fix thread-creation problem

When starting a thread, the thread was created and partially
initialized before trying to get a name for the thread from the given
thunk, but getting a name for the thunk could trigger scheduler
descisions, which could get confused by the partially initialized
thread.
---
 collects/tests/racket/thread.rktl |  7 +++++++
 src/racket/src/thread.c           | 17 ++++++++++-------
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/collects/tests/racket/thread.rktl b/collects/tests/racket/thread.rktl
index e8bf5125b4..151314def1 100644
--- a/collects/tests/racket/thread.rktl
+++ b/collects/tests/racket/thread.rktl
@@ -1453,6 +1453,13 @@
        (lambda () (set! v "yes"))))))
   (test "yes" values v))
 
+; --------------------
+;; Make sure that extracting a procedure name for a thread
+;; doesn't create trouble:
+
+(for ([i 1000])
+  (thread (make-keyword-procedure (lambda (x y) '()))))
+
 ; --------------------
 
 (report-errs)
diff --git a/src/racket/src/thread.c b/src/racket/src/thread.c
index 17b32e963d..0ad84580b0 100644
--- a/src/racket/src/thread.c
+++ b/src/racket/src/thread.c
@@ -2884,6 +2884,7 @@ static Scheme_Object *make_subprocess(Scheme_Object *child_thunk,
 {
   Scheme_Thread *child;
   int turn_on_multi;
+  Scheme_Object *name_sym = NULL;
  
   turn_on_multi = !scheme_first_thread->next;
   
@@ -2897,24 +2898,26 @@ static Scheme_Object *make_subprocess(Scheme_Object *child_thunk,
       maybe_recycle_cell = NULL;
   }
 
-  child = make_thread(config, cells, break_cell, mgr, child_start);
-
-  /* Use child_thunk name, if any, for the thread name: */
+  /* Use child_thunk name, if any, for the thread name.
+     (Get it before calling make_thread(), in case
+     getting the name blocks.) */
   {
-    Scheme_Object *sym;
     const char *s;
     int len;
     
     s = scheme_get_proc_name(child_thunk, &len, -1);
     if (s)  {
       if (len < 0)
-	sym = (Scheme_Object *)s;
+	name_sym = (Scheme_Object *)s;
       else
-	sym = scheme_intern_exact_symbol(s, len);
-      child->name = sym;
+	name_sym = scheme_intern_exact_symbol(s, len);
     }
   }
 
+  child = make_thread(config, cells, break_cell, mgr, child_start);
+  if (name_sym)
+    child->name = name_sym;
+
   {
     Scheme_Object *v;
     v = scheme_thread_cell_get(break_cell, cells);