Index: process.c
===================================================================
--- process.c	(リビジョン 27673)
+++ process.c	(作業コピー)
@@ -1331,13 +1331,10 @@
     fflush(stderr);
 #endif
 
-#if defined(__NetBSD__) || defined(__APPLE__) || defined(linux)
     before_exec();
-#endif
     pid = fork();
-#if defined(__NetBSD__) || defined(__APPLE__) || defined(linux)
     after_exec();
-#endif
+
     switch (pid) {
       case 0:
 #ifdef linux
@@ -1578,9 +1575,7 @@
 
     chfunc = signal(SIGCHLD, SIG_DFL);
   retry:
-#if defined(__NetBSD__) || defined(__APPLE__) || defined(linux)
     before_exec();
-#endif
     pid = fork();
     if (pid == 0) {
 	/* child process */
@@ -1588,9 +1583,7 @@
 	rb_protect(proc_exec_args, (VALUE)&earg, NULL);
 	_exit(127);
     }
-#if defined(__NetBSD__) || defined(__APPLE__) || defined(linux)
     after_exec();
-#endif
     if (pid < 0) {
 	if (errno == EAGAIN) {
 	    rb_thread_sleep(1);
Index: io.c
===================================================================
--- io.c	(リビジョン 27673)
+++ io.c	(作業コピー)
@@ -3271,9 +3271,7 @@
     }
 
   retry:
-#if defined(__NetBSD__) || defined(__APPLE__) || defined(linux)
     rb_thread_stop_timer();
-#endif
     switch ((pid = fork())) {
       case 0:			/* child */
 	if (modef & FMODE_READABLE) {
@@ -3301,17 +3299,13 @@
 		    ruby_sourcefile, ruby_sourceline, pname);
 	    _exit(127);
 	}
-#if defined(__NetBSD__) || defined(__APPLE__) || defined(linux)
 	rb_thread_start_timer();
-#endif
 	rb_io_synchronized(RFILE(orig_stdout)->fptr);
 	rb_io_synchronized(RFILE(orig_stderr)->fptr);
 	return Qnil;
 
       case -1:			/* fork failed */
-#if defined(__NetBSD__) || defined(__APPLE__) || defined(linux)
 	rb_thread_start_timer();
-#endif
 	if (errno == EAGAIN) {
 	    rb_thread_sleep(1);
 	    goto retry;
@@ -3332,9 +3326,7 @@
 	break;
 
       default:			/* parent */
-#if defined(__NetBSD__) || defined(__APPLE__) || defined(linux)
 	rb_thread_start_timer();
-#endif
 	if (pid < 0) rb_sys_fail(pname);
 	else {
 	    VALUE port = io_alloc(rb_cIO);
Index: eval.c
===================================================================
--- eval.c	(リビジョン 27673)
+++ eval.c	(作業コピー)
@@ -12524,9 +12524,6 @@
     safe_mutex_lock(&time_thread.lock);
     if (pthread_create(&time_thread.thread, 0, thread_timer, args) == 0) {
 	thread_init = 1;
-#if !defined(__NetBSD__) && !defined(__APPLE__) && !defined(linux)
-	pthread_atfork(0, 0, rb_thread_stop_timer);
-#endif
 	pthread_cond_wait(&start, &time_thread.lock);
     }
     pthread_cleanup_pop(1);