Hang on quit due to EditorResourcePreview destructor

[hedin-hiervard]

Godot version:

Godot 3.1 alpha 4

OS/device including version:

Issue description:

Pretty often Godot editor hangs on quit. Here is the stacktrace:

* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
  * frame #0: 0x00007fffcae17f46 libsystem_kernel.dylib`__semwait_signal + 10
    frame #1: 0x00007fffcaf046e5 libsystem_pthread.dylib`pthread_join + 425
    frame #2: 0x0000000106310fd2 godot.osx.tools.64`ThreadPosix::wait_to_finish_func_posix(p_thread=0x00007ff483759240) at thread_posix.cpp:100
    frame #3: 0x00000001082ee1d7 godot.osx.tools.64`Thread::wait_to_finish(p_thread=0x00007ff483759240) at thread.cpp:59
    frame #4: 0x0000000106802630 godot.osx.tools.64`EditorResourcePreview::~EditorResourcePreview(this=0x00007ff48376efd0) at editor_resource_preview.cpp:433
    frame #5: 0x00000001068027d5 godot.osx.tools.64`EditorResourcePreview::~EditorResourcePreview(this=0x00007ff48376efd0) at editor_resource_preview.cpp:429
    frame #6: 0x0000000106701132 godot.osx.tools.64`void memdelete<Node>(p_class=0x00007ff48376efd0) at memory.h:119
    frame #7: 0x0000000107024509 godot.osx.tools.64`Node::_notification(this=0x00007ff47c07cc10, p_notification=1) at node.cpp:162
    frame #8: 0x0000000106fd27e7 godot.osx.tools.64`Node::_notificationv(this=0x00007ff47c07cc10, p_notification=1, p_reversed=true) at node.h:46
    frame #9: 0x0000000106743729 godot.osx.tools.64`EditorNode::_notificationv(this=0x00007ff47c07cc10, p_notification=1, p_reversed=true) at editor_node.h:100
    frame #10: 0x0000000108109212 godot.osx.tools.64`Object::notification(this=0x00007ff47c07cc10, p_notification=1, p_reversed=true) at object.cpp:955
    frame #11: 0x00000001081091a9 godot.osx.tools.64`Object::_predelete(this=0x00007ff47c07cc10) at object.cpp:386
    frame #12: 0x000000010811c0e5 godot.osx.tools.64`predelete_handler(p_object=0x00007ff47c07cc10) at object.cpp:1999
    frame #13: 0x0000000106701115 godot.osx.tools.64`void memdelete<Node>(p_class=0x00007ff47c07cc10) at memory.h:117
    frame #14: 0x0000000107024509 godot.osx.tools.64`Node::_notification(this=0x00007ff47c8e6a10, p_notification=1) at node.cpp:162
    frame #15: 0x0000000106fd27e7 godot.osx.tools.64`Node::_notificationv(this=0x00007ff47c8e6a10, p_notification=1, p_reversed=true) at node.h:46
    frame #16: 0x00000001070ba189 godot.osx.tools.64`Viewport::_notificationv(this=0x00007ff47c8e6a10, p_notification=1, p_reversed=true) at viewport.h:94
    frame #17: 0x0000000108109212 godot.osx.tools.64`Object::notification(this=0x00007ff47c8e6a10, p_notification=1, p_reversed=true) at object.cpp:955
    frame #18: 0x00000001081091a9 godot.osx.tools.64`Object::_predelete(this=0x00007ff47c8e6a10) at object.cpp:386
    frame #19: 0x000000010811c0e5 godot.osx.tools.64`predelete_handler(p_object=0x00007ff47c8e6a10) at object.cpp:1999
    frame #20: 0x0000000107068c65 godot.osx.tools.64`void memdelete<Viewport>(p_class=0x00007ff47c8e6a10) at memory.h:117
    frame #21: 0x0000000107068c3e godot.osx.tools.64`SceneTree::finish(this=0x00007ff483220de0) at scene_tree.cpp:610
    frame #22: 0x0000000105708f4d godot.osx.tools.64`OS_OSX::run(this=0x00007fff5a5058f0) at os_osx.mm:2572
    frame #23: 0x0000000105710698 godot.osx.tools.64`main(argc=4, argv=0x00007fff5a506c48) at godot_main_osx.mm:100
    frame #24: 0x00007fffcace9235 libdyld.dylib`start + 1
    frame #25: 0x00007fffcace9235 libdyld.dylib`start + 1

Looks something called EditorResourcePreview deadlock the main thread.

Steps to reproduce:

Minimal reproduction project:

[akien-mga]

Similar to #24206, though the stacktrace is a bit different.

[reduz]

fixed by e8d31cc

[bruvzg]

EditorResourcePreview deadlock still happens in 22ee7ba

Main thread stack:

godot.osx.opt.tools.64!::wait_to_finish_func_posix() (godot/drivers/unix/thread_posix.cpp:111)
godot.osx.opt.tools.64!::stop() (godot/editor/editor_resource_preview.cpp:424)
godot.osx.opt.tools.64!_exit_editor (godot/editor/editor_node.cpp:2370)
godot.osx.opt.tools.64!::_discard_changes() (godot/editor/editor_node.cpp:2401)
godot.osx.opt.tools.64!::_menu_option_confirm() (godot/editor/editor_node.cpp:2167)
godot.osx.opt.tools.64!::call() (godot/core/method_bind.gen.inc:54)
godot.osx.opt.tools.64!::call() (godot/core/object.cpp:943)
godot.osx.opt.tools.64!::emit_signal() (godot/core/object.cpp:1229)
godot.osx.opt.tools.64!::emit_signal() (godot/core/object.cpp:1285)
godot.osx.opt.tools.64!::_ok_pressed() (godot/scene/gui/dialogs.cpp:387)
godot.osx.opt.tools.64!::call() (godot/core/method_bind.gen.inc:54)
godot.osx.opt.tools.64!::call() (godot/core/object.cpp:943)
godot.osx.opt.tools.64!::emit_signal() (godot/core/object.cpp:1229)
godot.osx.opt.tools.64!::emit_signal() (godot/core/object.cpp:1285)
godot.osx.opt.tools.64!::_gui_input() (godot/scene/gui/base_button.cpp:139)
godot.osx.opt.tools.64!::call() (godot/core/method_bind.gen.inc:729)
godot.osx.opt.tools.64!::call_multilevel() (godot/core/object.cpp:777)
godot.osx.opt.tools.64!::call_multilevel() (godot/core/object.cpp:883)
godot.osx.opt.tools.64!::_gui_call_input() (godot/scene/main/viewport.cpp:1542)
godot.osx.opt.tools.64!::_gui_input_event() (godot/scene/main/viewport.cpp:1912)
godot.osx.opt.tools.64!::input() (godot/scene/main/viewport.cpp:2666)
godot.osx.opt.tools.64!::_vp_input() (godot/scene/main/viewport.cpp:1320)
godot.osx.opt.tools.64!::call() (godot/core/method_bind.gen.inc:729)
godot.osx.opt.tools.64!::call() (godot/core/object.cpp:943)
godot.osx.opt.tools.64!::call() (godot/core/object.cpp:867)
godot.osx.opt.tools.64!::call_group_flags() (godot/scene/main/scene_tree.cpp:262)
godot.osx.opt.tools.64!::input_event() (godot/scene/main/scene_tree.cpp:418)
godot.osx.opt.tools.64!::_parse_input_event_impl() (godot/main/input_default.cpp:440)
godot.osx.opt.tools.64!push_input (godot/platform/osx/os_osx.mm:2574)
godot.osx.opt.tools.64!_mouseDownEvent (godot/platform/osx/os_osx.mm:614)
AppKit!-[NSWindow(NSEventRouting) _reallySendEvent:isDelayedEvent:]
AppKit!-[NSWindow(NSEventRouting) sendEvent:]
AppKit!-[NSApplication(NSEvent) sendEvent:]
godot.osx.opt.tools.64!-[GodotApplication sendEvent:] (godot/platform/osx/os_osx.mm:165)
godot.osx.opt.tools.64!process_events (godot/platform/osx/os_osx.mm:2526)
godot.osx.opt.tools.64!run (godot/platform/osx/os_osx.mm:2608)
godot.osx.opt.tools.64!main (godot/platform/osx/godot_main_osx.mm:100)

Preview generation thread stack:

godot.osx.opt.tools.64!cgsem_wait (godot/platform/osx/semaphore_osx.cpp:60)
godot.osx.opt.tools.64!::wait() (godot/platform/osx/semaphore_osx.cpp:74)
godot.osx.opt.tools.64!push_and_ret<VisualServer, Ref<Image> (VisualServer::*)(RID, int) const, RID, int, Ref<Image> > (godot/core/command_queue_mt.h:452)
godot.osx.opt.tools.64!::texture_get_data() (godot/servers/visual/visual_server_wrap_mt.h:88)
godot.osx.opt.tools.64!::get_data() (godot/scene/resources/texture.cpp:261)
godot.osx.opt.tools.64!::generate() (godot/editor/plugins/editor_preview_plugins.cpp:101)
godot.osx.opt.tools.64!::_generate_preview() (godot/editor/editor_resource_preview.cpp:151)
godot.osx.opt.tools.64!::_thread() (godot/editor/editor_resource_preview.cpp:223)
godot.osx.opt.tools.64!::thread_callback() (godot/drivers/unix/thread_posix.cpp:74)