I am facing an issue which seems to have changed since the Unity 5.x days. I am trying to run the Unity player in an Ubuntu server environment. Given that this environment is headless, I plan to use xvfb to create a virtual frame buffer.
Given that there is no compositor, Unity detects a 0Hz refresh rate. But in Unity 5.x, it still sets the target frame rate to 60 and runs perfectly, allowing me to render frames:
requesting fullscreen 1280 x 1024 at 0 Hz
Current window manager doesn't support fullscreen
(Filename: /home/builduser/buildslave/unity/build/PlatformDependent/Linux/X11Quarantine.cpp Line: 770)
Desktop is 1280 x 1024 @ 60 Hz
But Unity 6 doesn’t do this. It sets the screen resolution to 0Hz which means that apart from Awake calls in my scene, nothing gets rendered (no Start, no Update). This means Unity can’t be used for rendering in a headless Linux environment.
This breaks use cases like MLAgents with Visual Observations, among other things. Any insight from the Unity team?
Things I’ve Tried
Setting Application.targetFramerate = 60. Unity remains stuck with 0Hz.
Not sure what you are trying to achieve here. If you don’t want any graphic then you should either build for dedicated server or start your game with special arguments. Check the doc here.
If you want graphic then you need a compositor. Unity can’t run without one.
It’s not an Ubuntu issue at all. From what I can tell, Unity previously detected when it was running in a virtual X server and would manually implement a timer loop. Now, that seems to have been removed. It seems like an economic decision.
Unity 5.x hardcoded the refresh rate on Linux to 60, which would not work well with various displays. We now use SDL_GetDesktopDisplayMode to detect the refresh rate dynamically,
That said, Unity doesn’t actually block just because refresh rate is 0 - it is probably a red herring. I’d recommend attaching a debugger to see where it gets stuck.
Finally, as Lanre noted, rendering on the server isn’t a supported scenario so we don’t test this configuration and cannot guarantee it will work. That said, we did not intentionally break it either.
Thanks for the SDL_GetDesktopDisplayMode clue. I tried to use Xdummy and Xrandr to create a configuration with 1280x720@60Hz, and Unity correctly detects the 60Hz refresh rate. But I still get what seems to be a frozen player loop: no Start, no Update, no coroutine progress. Here’s my code:
private void Awake () {
Debug.Log($"Behaviour awake called with resolution: {Screen.currentResolution}");
Application.targetFrameRate = 30;
}
private IEnumerator Start () {
yield return new WaitForSeconds(3f);
Debug.Log("Starting long process");
yield return new WaitForSeconds(10f);
Debug.Log("Stopping long process");
}
And here are the logs from the server:
Preloaded 'lib_burst_generated.so'
Found 1 interfaces on host : 0) 172.20.12.27
Player connection [140695897624448] Multi-casting "[IP] 172.20.12.27 [Port] 55000 [Flags] 2 [Guid] 983717886 [EditorId] 2941397365 [Version] 1048832 [Id] LinuxPlayer(13,172.20.12.27) [Debug] 0 [PackageName] LinuxPlayer [ProjectName] linux" to [225.0.0.222:54997]...
Display 0 'DUMMY0': 1280x720 (primary device).
[Physics::Module] Initialized MultithreadedJobDispatcher with 11 workers.
Unable to load player prefs
Desktop is 1280 x 720 @ 59 Hz
Initialize engine version: 2022.3.23f1 (dbb3f7c5b5c6)
[Subsystems] Discovering subsystems at path /home/coder/mount/videokit_Data/UnitySubsystems
GfxDevice: creating device client; threaded=1; jobified=1
Renderer: llvmpipe (LLVM 15.0.6, 256 bits)
Vendor: Mesa/X.org
Version: 4.5 (Core Profile) Mesa 22.3.6
GLES: 0
GL_3DFX_texture_compression_FXT1 GL_AMD_conservative_depth GL_AMD_draw_buffers_blend GL_AMD_gpu_shader_int64 GL_AMD_multi_draw_indirect GL_AMD_pinned_memory GL_AMD_query_buffer_object GL_AMD_seamless_cubemap_per_texture GL_AMD_shader_stencil_export GL_AMD_shader_trinary_minmax GL_AMD_texture_texture4 GL_AMD_vertex_shader_layer GL_AMD_vertex_shader_viewport_index GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ARB_ES2_compatibility GL_ARB_ES3_1_compatibility GL_ARB_ES3_2_compatibility GL_ARB_ES3_compatibility GL_ARB_arrays_of_arrays GL_ARB_base_instance GL_ARB_blend_func_extended GL_ARB_buffer_storage GL_ARB_clear_buffer_object GL_ARB_clear_texture GL_ARB_clip_control GL_ARB_compressed_texture_pixel_storage GL_ARB_compute_shader GL_ARB_conditional_render_inverted GL_ARB_conservative_depth GL_ARB_copy_buffer GL_ARB_copy_image GL_ARB_cull_distance GL_ARB_debug_output GL_ARB_depth_buffer_float GL_ARB_depth_clamp GL_ARB_derivative_control GL_ARB_direct_state_access GL_ARB_draw_buffers GL_A
RB_draw_buffers_blend GL_ARB_draw_elements_base_vertex GL_ARB_draw_indirect GL_ARB_draw_instanced GL_ARB_enhanced_layouts GL_ARB_explicit_attrib_location GL_ARB_explicit_uniform_location GL_ARB_fragment_coord_conventions GL_ARB_fragment_layer_viewport GL_ARB_fragment_shader GL_ARB_framebuffer_no_attachments GL_ARB_framebuffer_object GL_ARB_framebuffer_sRGB GL_ARB_get_program_binary GL_ARB_get_texture_sub_image GL_ARB_gl_spirv GL_ARB_gpu_shader5 GL_ARB_gpu_shader_fp64 GL_ARB_gpu_shader_int64 GL_ARB_half_float_pixel GL_ARB_half_float_vertex GL_ARB_indirect_parameters GL_ARB_instanced_arrays GL_ARB_internalformat_query GL_ARB_internalformat_query2 GL_ARB_invalidate_subdata GL_ARB_map_buffer_alignment GL_ARB_map_buffer_range GL_ARB_multi_bind GL_ARB_multi_draw_indirect GL_ARB_occlusion_query2 GL_ARB_parallel_shader_compile GL_ARB_pipeline_statistics_query GL_ARB_pixel_buffer_object GL_ARB_point_sprite GL_ARB_polygon_offset_clamp GL_ARB_post_depth_coverage GL_ARB_program_interface_query GL_ARB_provoking_vertex GL
_ARB_query_buffer_object GL_ARB_robust_buffer_access_behavior GL_ARB_robustness GL_ARB_sample_shading GL_ARB_sampler_objects GL_ARB_seamless_cube_map GL_ARB_seamless_cubemap_per_texture GL_ARB_separate_shader_objects GL_ARB_shader_atomic_counter_ops GL_ARB_shader_atomic_counters GL_ARB_shader_ballot GL_ARB_shader_bit_encoding GL_ARB_shader_clock GL_ARB_shader_draw_parameters GL_ARB_shader_group_vote GL_ARB_shader_image_load_store GL_ARB_shader_image_size GL_ARB_shader_objects GL_ARB_shader_precision GL_ARB_shader_stencil_export GL_ARB_shader_storage_buffer_object GL_ARB_shader_subroutine GL_ARB_shader_texture_image_samples GL_ARB_shader_texture_lod GL_ARB_shader_viewport_layer_array GL_ARB_shading_language_420pack GL_ARB_shading_language_include GL_ARB_shading_language_packing GL_ARB_spirv_extensions GL_ARB_stencil_texturing GL_ARB_sync GL_ARB_tessellation_shader GL_ARB_texture_barrier GL_ARB_texture_buffer_object GL_ARB_texture_buffer_object_rgb32 GL_ARB_texture_buffer_range GL_ARB_texture_compression_bptc
GL_ARB_texture_compression_rgtc GL_ARB_texture_cube_map_array GL_ARB_texture_filter_anisotropic GL_ARB_texture_filter_minmax GL_ARB_texture_float GL_ARB_texture_gather GL_ARB_texture_mirror_clamp_to_edge GL_ARB_texture_multisample GL_ARB_texture_non_power_of_two GL_ARB_texture_query_levels GL_ARB_texture_query_lod GL_ARB_texture_rectangle GL_ARB_texture_rg GL_ARB_texture_rgb10_a2ui GL_ARB_texture_stencil8 GL_ARB_texture_storage GL_ARB_texture_storage_multisample GL_ARB_texture_swizzle GL_ARB_texture_view GL_ARB_timer_query GL_ARB_transform_feedback2 GL_ARB_transform_feedback3 GL_ARB_transform_feedback_instanced GL_ARB_transform_feedback_overflow_query GL_ARB_uniform_buffer_object GL_ARB_vertex_array_bgra GL_ARB_vertex_array_object GL_ARB_vertex_attrib_64bit GL_ARB_vertex_attrib_binding GL_ARB_vertex_buffer_object GL_ARB_vertex_shader GL_ARB_vertex_type_10f_11f_11f_rev GL_ARB_vertex_type_2_10_10_10_rev GL_ARB_viewport_array GL_ARM_shader_framebuffer_fetch_depth_stencil GL_ATI_blend_equation_separate GL_ATI_te
xture_float GL_ATI_texture_mirror_once GL_EXT_EGL_image_storage GL_EXT_EGL_sync GL_EXT_abgr GL_EXT_blend_equation_separate GL_EXT_debug_label GL_EXT_draw_buffers2 GL_EXT_draw_instanced GL_EXT_framebuffer_blit GL_EXT_framebuffer_multisample GL_EXT_framebuffer_multisample_blit_scaled GL_EXT_framebuffer_object GL_EXT_framebuffer_sRGB GL_EXT_memory_object GL_EXT_memory_object_fd GL_EXT_packed_depth_stencil GL_EXT_packed_float GL_EXT_pixel_buffer_object GL_EXT_polygon_offset_clamp GL_EXT_provoking_vertex GL_EXT_shader_framebuffer_fetch GL_EXT_shader_framebuffer_fetch_non_coherent GL_EXT_shader_integer_mix GL_EXT_texture_array GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc GL_EXT_texture_filter_anisotropic GL_EXT_texture_filter_minmax GL_EXT_texture_integer GL_EXT_texture_mirror_clamp GL_EXT_texture_sRGB GL_EXT_texture_sRGB_R8 GL_EXT_texture_sRGB_RG8 GL_EXT_texture_sRGB_decode GL_EXT_texture_shadow_lod GL_EXT_texture_shared_exponent GL_EXT_texture_snorm GL_EXT_textu
re_swizzle GL_EXT_timer_query GL_EXT_transform_feedback GL_EXT_vertex_array_bgra GL_EXT_vertex_attrib_64bit GL_IBM_multimode_draw_arrays GL_INTEL_shader_atomic_float_minmax GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent GL_KHR_context_flush_control GL_KHR_debug GL_KHR_no_error GL_KHR_parallel_shader_compile GL_KHR_robust_buffer_access_behavior GL_KHR_robustness GL_KHR_texture_compression_astc_ldr GL_KHR_texture_compression_astc_sliced_3d GL_MESA_framebuffer_flip_y GL_MESA_pack_invert GL_MESA_shader_integer_functions GL_MESA_texture_signed_rgba GL_MESA_ycbcr_texture GL_NV_conditional_render GL_NV_copy_image GL_NV_depth_clamp GL_NV_packed_depth_stencil GL_NV_shader_atomic_float GL_NV_texture_barrier GL_OES_EGL_image GL_S3_s3tc
OPENGL LOG: Creating OpenGL 4.5 graphics device ; Context level <OpenGL 4.5> ; Context handle 6141968
ALSA lib confmisc.c:855:(parse_card) cannot find card '0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_card_inum returned error: No such file or directory
ALSA lib confmisc.c:422:(snd_func_concat) error evaluating strings
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1334:(snd_func_refer) error evaluating name
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM default
FMOD failed to initialize the output device.: "Error initializing output device. " (60)
Forced to initialize FMOD to to the device driver's system output rate 48000, this may impact performance and/or give inconsistent experiences compared to selected sample rate 48000
ALSA lib confmisc.c:855:(parse_card) cannot find card '0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_card_inum returned error: No such file or directory
ALSA lib confmisc.c:422:(snd_func_concat) error evaluating strings
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1334:(snd_func_refer) error evaluating name
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM default
FMOD failed to initialize the output device.: "Error initializing output device. " (60)
FMOD failed to initialize the output device.: "An error occured that wasn't supposed to. Contact support. " (33)
Unable to initalize any audio device (even FMOD nosound device), please check your audio drivers and/or hardware for malfunction
Default vsync count 0
requesting resize 1280 x 720
Using native desktop resolution 1280 x 720
requesting fullscreen 1280 x 720 at 0/1 Hz
Desktop is 1280 x 720 @ 59 Hz
UnloadTime: 1.463011 ms
Behaviour awake called with refresh rate: 1280 x 720 @ 59Hz
UnityEngine.DebugLogHandler:Internal_Log(LogType, LogOption, String, Object)
UnityEngine.DebugLogHandler:LogFormat(LogType, Object, String, Object[])
UnityEngine.Logger:Log(LogType, Object)
UnityEngine.Debug:Log(Object)
RecordVideo:Awake()
I assumed that once Unity gets the current SDL_DisplayMode, it starts a player loop that runs at intervals based on the refresh_rate. Is there something else I’m missing?
I assumed that once Unity gets the current SDL_DisplayMode, it starts a player loop that runs at intervals based on the refresh_rate. Is there something else I’m missing?
No, this isn’t how it works. As I mentioned above, Unity doesn’t use refresh rate like that. Refresh rate is generally only used to slightly alter deltaTime to provide smoother visuals. Other than that, we depend on the graphics driver to align us with monitor refresh rate if VSync is enabled.
It seems that Unity is hanging somewhere on your system. I recommend attaching a debugger and dumping callstacks of all threads. That should give you a clue what it hangs on.
Other than that, we depend on the graphics driver to align us with monitor refresh rate if VSync is enabled.
@Tautvydas-Zilys what if Vsync is disabled? I explicitly disable Vsync because I’m running in a containerized environment, with a software GL driver and virtual frame buffer.
It seems that Unity is hanging somewhere on your system. I recommend attaching a debugger and dumping callstacks of all threads. That should give you a clue what it hangs on.
I’ve been trying to run this in the cloud (i.e. can’t attach a debugger without elevated privileges), but will try to get a physical Linux box to continue testing on.
@Tautvydas-Zilys what if Vsync is disabled? I explicitly disable Vsync because I’m running in a containerized environment, with a software GL driver and virtual frame buffer.
Then it will try to run as fast as possible, unless you configure Application.targetFrameRate to run slower.