godot: Godot 3.2.4rc3 mono crashes on exit with specific combination of packed scene and dynamic font

I meant the Godot debugger, if it some day it gets features to debug GDScript threads. But, again, that’s not relevant now. If that happens at some point, we will just decide how to deal with it then.

For Godot debugger we can add get/set_thread_name() and Map<ID, String> to make it even more readable.

Indeed, see #46411 (comment) where @neikeq has come to the same conclusion (he’s preparing a fix).

In case it’s useful, here’s my patch, which fixes crash on macOS (I have not tested it on any other platforms).

diff --git a/core/os/thread.cpp b/core/os/thread.cpp
index 58b29b9802..61cc31e154 100644
--- a/core/os/thread.cpp
+++ b/core/os/thread.cpp
@@ -41,9 +41,13 @@ void (*Thread::set_priority_func)(Thread::Priority) = nullptr;
 void (*Thread::init_func)() = nullptr;
 void (*Thread::term_func)() = nullptr;
 
-Thread::ID Thread::main_thread_id = 1;
-SafeNumeric<Thread::ID> Thread::last_thread_id{ 1 };
-thread_local Thread::ID Thread::caller_id = 1;
+uint64_t _thread_id_hash(const std::thread::id &p_t) {
+	static std::hash<std::thread::id> hasher;
+	return hasher(p_t);
+}
+
+Thread::ID Thread::main_thread_id = _thread_id_hash(std::this_thread::get_id());
+thread_local Thread::ID Thread::caller_id = _thread_id_hash(std::this_thread::get_id());
 
 void Thread::_set_platform_funcs(
 		Error (*p_set_name_func)(const String &),
@@ -57,7 +61,7 @@ void Thread::_set_platform_funcs(
 }
 
 void Thread::callback(Thread *p_self, const Settings &p_settings, Callback p_callback, void *p_userdata) {
-	Thread::caller_id = p_self->id;
+	Thread::caller_id = _thread_id_hash(p_self->thread.get_id());
 	if (set_priority_func) {
 		set_priority_func(p_settings.priority);
 	}
@@ -73,7 +77,7 @@ void Thread::callback(Thread *p_self, const Settings &p_settings, Callback p_cal
 }
 
 void Thread::start(Thread::Callback p_callback, void *p_user, const Settings &p_settings) {
-	if (id != 0) {
+	if (id != _thread_id_hash(std::thread::id())) {
 #ifdef DEBUG_ENABLED
 		WARN_PRINT("A Thread object has been re-started without wait_to_finish() having been called on it. Please do so to ensure correct cleanup of the thread.");
 #endif
@@ -81,22 +85,22 @@ void Thread::start(Thread::Callback p_callback, void *p_user, const Settings &p_
 		std::thread empty_thread;
 		thread.swap(empty_thread);
 	}
-	id = last_thread_id.increment();
 	std::thread new_thread(&Thread::callback, this, p_settings, p_callback, p_user);
 	thread.swap(new_thread);
+	id = _thread_id_hash(thread.get_id());
 }
 
 bool Thread::is_started() const {
-	return id != 0;
+	return id != _thread_id_hash(std::thread::id());
 }
 
 void Thread::wait_to_finish() {
-	if (id != 0) {
+	if (id != _thread_id_hash(std::thread::id())) {
 		ERR_FAIL_COND_MSG(id == get_caller_id(), "A Thread can't wait for itself to finish.");
 		thread.join();
 		std::thread empty_thread;
 		thread.swap(empty_thread);
-		id = 0;
+		id = _thread_id_hash(std::thread::id());
 	}
 }
 
@@ -109,10 +113,10 @@ Error Thread::set_name(const String &p_name) {
 }
 
 Thread::Thread() :
-		id(0) {}
+		id(_thread_id_hash(std::thread::id())) {}
 
 Thread::~Thread() {
-	if (id != 0) {
+	if (id != _thread_id_hash(std::thread::id())) {
 #ifdef DEBUG_ENABLED
 		WARN_PRINT("A Thread object has been destroyed without wait_to_finish() having been called on it. Please do so to ensure correct cleanup of the thread.");
 #endif
diff --git a/core/os/thread.h b/core/os/thread.h
index 837f9323c3..38763e2ebc 100644
--- a/core/os/thread.h
+++ b/core/os/thread.h
@@ -62,7 +62,6 @@ private:
 	friend class Main;
 
 	static ID main_thread_id;
-	static SafeNumeric<ID> last_thread_id;
 
 	ID id;
 	static thread_local ID caller_id;

Edit: Added default std::thread::id() values instead of zeros.