normal	2018-06-30 09:51:57 +0900 (Sat, 30 Jun 2018)

  New Revision: 63795

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=63795

  Log:
    use SIGCHLD_LOSSY to enable waitpid polling mode
    
    Some systems lack SIGCHLD or have incomplete SIGCHLD
    implementations.  So enable polling mode for them.
    
    [ruby-core:87705] [Bug #14867]

  Modified files:
    trunk/mjit.c
    trunk/process.c
    trunk/signal.c
    trunk/thread_pthread.c
    trunk/vm_core.h
Index: mjit.c
===================================================================
--- mjit.c	(revision 63794)
+++ mjit.c	(revision 63795)
@@ -408,7 +408,7 @@ exec_process(const char *path, char *con https://github.com/ruby/ruby/blob/trunk/mjit.c#L408
 {
     int stat, exit_code = -2;
     pid_t pid;
-    rb_vm_t *vm = RUBY_SIGCHLD ? GET_VM() : 0;
+    rb_vm_t *vm = (RUBY_SIGCHLD || SIGCHLD_LOSSY) ? GET_VM() : 0;
     rb_nativethread_cond_t cond;
 
     if (vm) {
Index: process.c
===================================================================
--- process.c	(revision 63794)
+++ process.c	(revision 63795)
@@ -1126,7 +1126,7 @@ rb_waitpid(rb_pid_t pid, int *st, int fl https://github.com/ruby/ruby/blob/trunk/process.c#L1126
     waitpid_state_init(&w, pid, flags);
     w.ec = GET_EC();
 
-    if (RUBY_SIGCHLD) {
+    if (RUBY_SIGCHLD || SIGCHLD_LOSSY) {
         waitpid_wait(&w);
     }
     else {
Index: signal.c
===================================================================
--- signal.c	(revision 63794)
+++ signal.c	(revision 63795)
@@ -1066,7 +1066,7 @@ void ruby_waitpid_all(rb_vm_t *); /* pro https://github.com/ruby/ruby/blob/trunk/signal.c#L1066
 void
 ruby_sigchld_handler(rb_vm_t *vm)
 {
-    if (ATOMIC_EXCHANGE(sigchld_hit, 0)) {
+    if (SIGCHLD_LOSSY || ATOMIC_EXCHANGE(sigchld_hit, 0)) {
         ruby_waitpid_all(vm);
     }
 }
Index: thread_pthread.c
===================================================================
--- thread_pthread.c	(revision 63794)
+++ thread_pthread.c	(revision 63795)
@@ -1375,6 +1375,16 @@ timer_thread_sleep(rb_global_vm_lock_t* https://github.com/ruby/ruby/blob/trunk/thread_pthread.c#L1375
 
     need_polling = !ubf_threads_empty();
 
+    if (SIGCHLD_LOSSY && !need_polling) {
+        rb_vm_t *vm = container_of(gvl, rb_vm_t, gvl);
+
+        rb_native_mutex_lock(&vm->waitpid_lock);
+        if (!list_empty(&vm->waiting_pids) || !list_empty(&vm->waiting_grps)) {
+            need_polling = 1;
+        }
+        rb_native_mutex_unlock(&vm->waitpid_lock);
+    }
+
     if (gvl->waiting > 0 || need_polling) {
 	/* polling (TIME_QUANTUM_USEC usec) */
 	result = poll(pollfds, 1, TIME_QUANTUM_USEC/1000);
Index: vm_core.h
===================================================================
--- vm_core.h	(revision 63794)
+++ vm_core.h	(revision 63795)
@@ -100,6 +100,13 @@ https://github.com/ruby/ruby/blob/trunk/vm_core.h#L100
 #  define RUBY_SIGCHLD    (0)
 #endif
 
+/* platforms with broken or non-existent SIGCHLD work by polling */
+#if defined(__APPLE__) || defined(__WIN32__)
+#  define SIGCHLD_LOSSY (1)
+#else
+#  define SIGCHLD_LOSSY (0)
+#endif
+
 #ifdef HAVE_STDARG_PROTOTYPES
 #include <stdarg.h>
 #define va_init_list(a,b) va_start((a),(b))

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