Remove coordinator and support forking

internal/mmtk.h

@@ -26,8 +26,6 @@ typedef uint32_t MMTk_AllocationSemantics;
 
 #define MMTK_MIN_OBJ_ALIGN 8
 
-#define MMTK_GC_THREAD_KIND_CONTROLLER 0
-
 #define MMTK_GC_THREAD_KIND_WORKER 1
 
 typedef struct RubyBindingOptions {
@@ -146,6 +144,10 @@ bool mmtk_will_never_move(MMTk_ObjectReference object);
 
 void mmtk_initialize_collection(MMTk_VMThread tls);
 
+void mmtk_prepare_to_fork(void);
+
+void mmtk_after_fork(MMTk_VMThread tls);
+
 void mmtk_enable_collection(void);
 
 void mmtk_disable_collection(void);

internal/mmtk_support.h

@@ -101,6 +101,10 @@ VALUE* rb_mmtk_objbuf_to_elems(rb_mmtk_objbuf_t* objbuf);
 
 void rb_mmtk_pin_array_buffer(VALUE array, volatile VALUE *stack_slot);
 
+// Forking support
+void rb_mmtk_shutdown_gc_threads(void);
+void rb_mmtk_respawn_gc_threads(void);
+
 // MMTk-specific Ruby module (GC::MMTk)
 void rb_mmtk_define_gc_mmtk_module(void);
 VALUE rb_mmtk_plan_name(VALUE _);

mmtk_support.c

@@ -1098,6 +1098,20 @@ rb_mmtk_pin_array_buffer(VALUE array, volatile VALUE *stack_slot)
     }
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// Forking support
+////////////////////////////////////////////////////////////////////////////////
+void
+rb_mmtk_shutdown_gc_threads(void)
+{
+    mmtk_prepare_to_fork();
+}
+
+void rb_mmtk_respawn_gc_threads(void)
+{
+    mmtk_after_fork(GET_THREAD());
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // MMTk-specific Ruby module (GC::MMTk)
 ////////////////////////////////////////////////////////////////////////////////

process.c

@@ -1677,11 +1677,21 @@ static void
 before_fork_ruby(void)
 {
     before_exec();
+#if USE_MMTK
+    if (rb_mmtk_enabled_p()) {
+        rb_mmtk_shutdown_gc_threads();
+    }
+#endif
 }
 
 static void
 after_fork_ruby(rb_pid_t pid)
 {
+#if USE_MMTK
+    if (rb_mmtk_enabled_p()) {
+        rb_mmtk_respawn_gc_threads();
+    }
+#endif
     rb_threadptr_pending_interrupt_clear(GET_THREAD());
     if (pid == 0) {
         // child
@@ -9236,15 +9246,7 @@ InitVM_process(void)
 #endif
 
     rb_define_singleton_method(rb_mProcess, "exec", f_exec, -1);
-#if USE_MMTK
-    // FIXME: MMTk currently doesn't support forking, so Process will not respond to :fork for not.
-    // We should add necessary mechanism to mmtk-core in order to support forking.
-    if (!rb_mmtk_enabled_p()) {
-#endif
     rb_define_singleton_method(rb_mProcess, "fork", rb_f_fork, 0);
-#if USE_MMTK
-    }
-#endif
     rb_define_singleton_method(rb_mProcess, "spawn", rb_f_spawn, -1);
     rb_define_singleton_method(rb_mProcess, "exit!", rb_f_exit_bang, -1);
     rb_define_singleton_method(rb_mProcess, "exit", f_exit, -1);

test/ruby/test_process.rb

@@ -1920,7 +1920,8 @@ def test_daemon_detached
       end
     end
 
-    if File.directory?("/proc/self/task") && /netbsd[a-z]*[1-6]/ !~ RUBY_PLATFORM
+    # Note: MMTk has many GC worker threads, and they will be visible in /proc/self/task.
+    if File.directory?("/proc/self/task") && /netbsd[a-z]*[1-6]/ !~ RUBY_PLATFORM && !defined?(GC::MMTk)
       def test_daemon_no_threads
         pid, data = IO.popen("-", "r+") do |f|
           break f.pid, f.readlines if f
@@ -1931,7 +1932,7 @@ def test_daemon_no_threads
         assert_include(1..2, data.size, bug4920)
         assert_not_include(data.map(&:to_i), pid)
       end
-    else # darwin
+    else # darwin or MMTk
       def test_daemon_no_threads
         data = EnvUtil.timeout(3) do
           IO.popen("-") do |f|