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]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63795 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 10 insertions, 0 deletions

diff --git a/thread_pthread.c b/thread_pthread.c
index 6ac7728ad9..401fc0c774 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -1375,6 +1375,16 @@ timer_thread_sleep(rb_global_vm_lock_t* gvl)
 
     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);