Fix Cycles Embree crash on macOS, due to too small thread stack size.

intern/cycles/util/util_thread.cpp

@@ -26,7 +26,17 @@ thread::thread(function<void()> run_cb, int node)
     joined_(false),
 	node_(node)
 {
-	thread_ = std::thread(&thread::run, this);
+#ifdef __APPLE__
+	/* Set the stack size to 2MB to match Linux. The default 512KB on macOS is
+	 * too small for Embree, and consistent stack size also makes things more
+	 * predictable in general. */
+	pthread_attr_t attribute;
+	pthread_attr_init(&attribute);
+	pthread_attr_setstacksize(&attribute, 1024*1024*2);
+	pthread_create(&pthread_id, &attribute, run, (void*)this);
+#else
+	std_thread = std::thread(&thread::run, this);
+#endif
 }
 
 thread::~thread()
@@ -49,13 +59,17 @@ void *thread::run(void *arg)
 bool thread::join()
 {
 	joined_ = true;
+#ifdef __APPLE__
+	return pthread_join(pthread_id, NULL) == 0;
+#else
 	try {
-		thread_.join();
+		std_thread.join();
 		return true;
 	}
 	catch (const std::system_error&) {
 		return false;
 	}
+#endif
 }
 
 CCL_NAMESPACE_END

intern/cycles/util/util_thread.h

@@ -41,8 +41,8 @@ typedef std::mutex thread_mutex;
 typedef std::unique_lock<std::mutex> thread_scoped_lock;
 typedef std::condition_variable thread_condition_variable;
 
-/* own pthread based implementation, to avoid boost version conflicts with
- * dynamically loaded blender plugins */
+/* Own thread implementation similar to std::thread, so we can set a
+ * custom stack size on macOS. */
 
 class thread {
 public:
@@ -56,7 +56,11 @@ public:
 
 protected:
 	function<void()> run_cb_;
-	std::thread thread_;
+#ifdef __APPLE__
+	pthread_t pthread_id;
+#else
+	std::thread std_thread;
+#endif
 	bool joined_;
 	int node_;
 };