Use the ThreadPool for all isolates and native ports. Previously,

runtime/vm/dart.cc

Index: runtime/vm/dart.cc
===================================================================
--- runtime/vm/dart.cc	(revision 6423)
+++ runtime/vm/dart.cc	(working copy)
@@ -16,6 +16,7 @@
 #include "vm/port.h"
 #include "vm/snapshot.h"
 #include "vm/stub_code.h"
+#include "vm/thread_pool.h"
 #include "vm/virtual_memory.h"
 #include "vm/zone.h"
 
@@ -24,6 +25,7 @@
 DECLARE_FLAG(bool, trace_isolates);
 
 Isolate* Dart::vm_isolate_ = NULL;
+ThreadPool* Dart::thread_pool_ = NULL;
 DebugInfo* Dart::pprof_symbol_generator_ = NULL;
 
 bool Dart::InitOnce(Dart_IsolateCreateCallback create,
@@ -39,6 +41,8 @@
   FreeListElement::InitOnce();
   Api::InitOnce();
   // Create the VM isolate and finish the VM initialization.
+  ASSERT(thread_pool_ == NULL);
+  thread_pool_ = new ThreadPool();

[siva, 2012/04/14 00:29:53]

I guess we don't have a Dart::Cleanup(...) where we can
shutdown the thread pool.

[turnidge, 2012/04/17 23:46:55]

True.  Added a TODO.

   {
     ASSERT(vm_isolate_ == NULL);
     ASSERT(Flags::Initialized());