Only start WebGPU thread if an adapter is requested

15 files changed, 200 insertions, 147 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 9b94f4d4277..df3badcb5f6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4639,6 +4639,7 @@ dependencies = [
  "serde",
  "servo_atoms",
  "servo_url",
+ "smallvec 0.6.10",
  "style_traits",
  "time",
  "url",
diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index c5fd3a5fd39..89d0b4462a1 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -173,7 +173,7 @@ use std::sync::Arc;
 use std::thread;
 use style_traits::viewport::ViewportConstraints;
 use style_traits::CSSPixel;
-use webgpu::WebGPU;
+use webgpu::{WebGPU, WebGPURequest};
 use webvr_traits::{WebVREvent, WebVRMsg};
 
 type PendingApprovalNavigations = HashMap<PipelineId, (LoadData, HistoryEntryReplacement)>;
@@ -242,6 +242,9 @@ struct BrowsingContextGroup {
     /// share an event loop, since they can use `document.domain`
     /// to become same-origin, at which point they can share DOM objects.
     event_loops: HashMap<Host, Weak<EventLoop>>,
+
+    /// The set of all WebGPU channels in this BrowsingContextGroup.
+    webgpus: HashMap<Host, WebGPU>,
 }
 
 /// The `Constellation` itself. In the servo browser, there is one
@@ -450,10 +453,6 @@ pub struct Constellation<Message, LTF, STF> {
     /// Entry point to create and get channels to a WebGLThread.
     webgl_threads: Option<WebGLThreads>,
 
-    /// An IPC channel for the constellation to send messages to the
-    /// WebGPU threads.
-    webgpu: Option<WebGPU>,
-
     /// A channel through which messages can be sent to the webvr thread.
     webvr_chan: Option<IpcSender<WebVRMsg>>,
 
@@ -537,9 +536,6 @@ pub struct InitialConstellationState {
     /// Entry point to create and get channels to a WebGLThread.
     pub webgl_threads: Option<WebGLThreads>,
 
-    /// A channel to the WebGPU threads.
-    pub webgpu: Option<WebGPU>,
-
     /// A channel to the webgl thread.
     pub webvr_chan: Option<IpcSender<WebVRMsg>>,
 
@@ -973,7 +969,6 @@ where
                         (rng, prob)
                     }),
                     webgl_threads: state.webgl_threads,
-                    webgpu: state.webgpu,
                     webvr_chan: state.webvr_chan,
                     webxr_registry: state.webxr_registry,
                     canvas_chan,
@@ -1230,7 +1225,6 @@ where
                 .webgl_threads
                 .as_ref()
                 .map(|threads| threads.pipeline()),
-            webgpu: self.webgpu.clone(),
             webvr_chan: self.webvr_chan.clone(),
             webxr_registry: self.webxr_registry.clone(),
             player_context: self.player_context.clone(),
@@ -1945,9 +1939,65 @@ where
                     EmbedderMsg::MediaSessionEvent(event),
                 ));
             },
+            FromScriptMsg::RequestAdapter(sender, options, ids) => self
+                .handle_request_wgpu_adapter(
+                    source_pipeline_id,
+                    BrowsingContextId::from(source_top_ctx_id),
+                    FromScriptMsg::RequestAdapter(sender, options, ids),
+                ),
         }
     }
 
+    fn handle_request_wgpu_adapter(
+        &mut self,
+        source_pipeline_id: PipelineId,
+        browsing_context_id: BrowsingContextId,
+        request: FromScriptMsg,
+    ) {
+        let browsing_context_group_id = match self.browsing_contexts.get(&browsing_context_id) {
+            Some(bc) => &bc.bc_group_id,
+            None => return warn!("Browsing context not found"),
+        };
+        let host = match self
+            .pipelines
+            .get(&source_pipeline_id)
+            .map(|pipeline| &pipeline.url)
+        {
+            Some(ref url) => match reg_host(&url) {
+                Some(host) => host,
+                None => return warn!("Invalid host url"),
+            },
+            None => return warn!("ScriptMsg from closed pipeline {:?}.", source_pipeline_id),
+        };
+        match self
+            .browsing_context_group_set
+            .get_mut(&browsing_context_group_id)
+        {
+            Some(browsing_context_group) => {
+                let adapter_request =
+                    if let FromScriptMsg::RequestAdapter(sender, options, ids) = request {
+                        WebGPURequest::RequestAdapter(sender, options, ids)
+                    } else {
+                        return warn!("Wrong message type in handle_request_wgpu_adapter");
+                    };
+                let send = match browsing_context_group.webgpus.entry(host) {
+                    Entry::Vacant(v) => v
+                        .insert(match WebGPU::new() {
+                            Some(webgpu) => webgpu,
+                            None => return warn!("Failed to create new WebGPU thread"),
+                        })
+                        .0
+                        .send(adapter_request),
+                    Entry::Occupied(o) => o.get().0.send(adapter_request),
+                };
+                if send.is_err() {
+                    return warn!("Failed to send request adapter message on WebGPU channel");
+                }
+            },
+            None => return warn!("Browsing context group not found"),
+        };
+    }
+
     fn handle_request_from_layout(&mut self, message: FromLayoutMsg) {
         debug!("Constellation got {:?} message", message);
         match message {
@@ -2496,12 +2546,25 @@ where
             }
         }
 
-        if let Some(webgpu) = self.webgpu.as_ref() {
-            debug!("Exiting WebGPU thread.");
-            let (sender, receiver) = ipc::channel().expect("Failed to create IPC channel!");
-            if let Err(e) = webgpu.exit(sender) {
-                warn!("Exit WebGPU Thread failed ({})", e);
-            }
+        debug!("Exiting WebGPU threads.");
+        let receivers = self
+            .browsing_context_group_set
+            .values()
+            .map(|browsing_context_group| {
+                browsing_context_group.webgpus.values().map(|webgpu| {
+                    let (sender, receiver) = ipc::channel().expect("Failed to create IPC channel!");
+                    if let Err(e) = webgpu.exit(sender) {
+                        warn!("Exit WebGPU Thread failed ({})", e);
+                        None
+                    } else {
+                        Some(receiver)
+                    }
+                })
+            })
+            .flatten()
+            .filter_map(|r| r);
+
+        for receiver in receivers {
             if let Err(e) = receiver.recv() {
                 warn!("Failed to receive exit response from WebGPU ({})", e);
             }
diff --git a/components/constellation/pipeline.rs b/components/constellation/pipeline.rs
index defa7f2e7a9..e81f1ab58ae 100644
--- a/components/constellation/pipeline.rs
+++ b/components/constellation/pipeline.rs
@@ -48,7 +48,6 @@ use std::process;
 use std::rc::Rc;
 use std::sync::atomic::AtomicBool;
 use std::sync::Arc;
-use webgpu::WebGPU;
 use webvr_traits::WebVRMsg;
 
 /// A `Pipeline` is the constellation's view of a `Document`. Each pipeline has an
@@ -194,9 +193,6 @@ pub struct InitialPipelineState {
     /// A channel to the WebGL thread.
     pub webgl_chan: Option<WebGLPipeline>,
 
-    /// A channel to the WebGPU threads.
-    pub webgpu: Option<WebGPU>,
-
     /// A channel to the webvr thread.
     pub webvr_chan: Option<IpcSender<WebVRMsg>>,
 
@@ -309,7 +305,6 @@ impl Pipeline {
                     webrender_document: state.webrender_document,
                     webgl_chan: state.webgl_chan,
                     webvr_chan: state.webvr_chan,
-                    webgpu: state.webgpu,
                     webxr_registry: state.webxr_registry,
                     player_context: state.player_context,
                 };
@@ -516,7 +511,6 @@ pub struct UnprivilegedPipelineContent {
     webrender_image_api_sender: net_traits::WebrenderIpcSender,
     webrender_document: webrender_api::DocumentId,
     webgl_chan: Option<WebGLPipeline>,
-    webgpu: Option<WebGPU>,
     webvr_chan: Option<IpcSender<WebVRMsg>>,
     webxr_registry: webxr_api::Registry,
     player_context: WindowGLContext,
@@ -569,7 +563,6 @@ impl UnprivilegedPipelineContent {
                 pipeline_namespace_id: self.pipeline_namespace_id,
                 content_process_shutdown_chan: content_process_shutdown_chan,
                 webgl_chan: self.webgl_chan,
-                webgpu: self.webgpu,
                 webvr_chan: self.webvr_chan,
                 webxr_registry: self.webxr_registry,
                 webrender_document: self.webrender_document,
diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index 3bad24b1b1d..f15358684e6 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -521,6 +521,7 @@ unsafe_no_jsmanaged_fields!(WebGLTextureId);
 unsafe_no_jsmanaged_fields!(WebGLVertexArrayId);
 unsafe_no_jsmanaged_fields!(WebGLVersion);
 unsafe_no_jsmanaged_fields!(WebGLSLVersion);
+unsafe_no_jsmanaged_fields!(RefCell<Option<WebGPU>>);
 unsafe_no_jsmanaged_fields!(RefCell<Identities>);
 unsafe_no_jsmanaged_fields!(WebGPU);
 unsafe_no_jsmanaged_fields!(WebGPUAdapter);
diff --git a/components/script/dom/gpu.rs b/components/script/dom/gpu.rs
index 8a3e05f2d79..4c4bd830f6e 100644
--- a/components/script/dom/gpu.rs
+++ b/components/script/dom/gpu.rs
@@ -19,9 +19,10 @@ use dom_struct::dom_struct;
 use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
 use js::jsapi::Heap;
+use script_traits::ScriptMsg;
 use std::rc::Rc;
 use webgpu::wgpu;
-use webgpu::{WebGPU, WebGPURequest, WebGPUResponse, WebGPUResponseResult};
+use webgpu::{WebGPUResponse, WebGPUResponseResult};
 
 #[dom_struct]
 pub struct GPU {
@@ -38,10 +39,6 @@ impl GPU {
     pub fn new(global: &GlobalScope) -> DomRoot<GPU> {
         reflect_dom_object(Box::new(GPU::new_inherited()), global, GPUBinding::Wrap)
     }
-
-    fn wgpu_channel(&self) -> Option<WebGPU> {
-        self.global().as_window().webgpu_channel()
-    }
 }
 
 pub trait AsyncWGPUListener {
@@ -114,7 +111,8 @@ impl GPUMethods for GPU {
         options: &GPURequestAdapterOptions,
         comp: InCompartment,
     ) -> Rc<Promise> {
-        let promise = Promise::new_in_current_compartment(&self.global(), comp);
+        let global = &self.global();
+        let promise = Promise::new_in_current_compartment(global, comp);
         let sender = response_async(&promise, self);
         let power_preference = match options.powerPreference {
             Some(GPUPowerPreference::Low_power) => wgpu::instance::PowerPreference::LowPower,
@@ -123,21 +121,21 @@ impl GPUMethods for GPU {
             },
             None => wgpu::instance::PowerPreference::Default,
         };
-        let ids = self.global().as_window().Navigator().create_adapter_ids();
+        let ids = global.as_window().Navigator().create_adapter_ids();
 
-        match self.wgpu_channel() {
-            Some(channel) => {
-                channel
-                    .0
-                    .send(WebGPURequest::RequestAdapter(
-                        sender,
-                        wgpu::instance::RequestAdapterOptions { power_preference },
-                        ids,
-                    ))
-                    .unwrap();
-            },
-            None => promise.reject_error(Error::Type("No WebGPU thread...".to_owned())),
-        };
+        let script_to_constellation_chan = global.script_to_constellation_chan();
+        if script_to_constellation_chan
+            .send(ScriptMsg::RequestAdapter(
+                sender,
+                wgpu::instance::RequestAdapterOptions { power_preference },
+                ids,
+            ))
+            .is_err()
+        {
+            promise.reject_error(Error::Type(
+                "Failed to send adapter request to constellation...".to_owned(),
+            ));
+        }
         promise
     }
 }
@@ -145,9 +143,10 @@ impl GPUMethods for GPU {
 impl AsyncWGPUListener for GPU {
     fn handle_response(&self, response: WebGPUResponse, promise: &Rc<Promise>) {
         match response {
-            WebGPUResponse::RequestAdapter(name, adapter) => {
+            WebGPUResponse::RequestAdapter(name, adapter, channel) => {
                 let adapter = GPUAdapter::new(
                     &self.global(),
+                    channel,
                     DOMString::from(format!("{} ({:?})", name, adapter.0.backend())),
                     Heap::default(),
                     adapter,
diff --git a/components/script/dom/gpuadapter.rs b/components/script/dom/gpuadapter.rs
index cbb24917ebe..80438c305ac 100644
--- a/components/script/dom/gpuadapter.rs
+++ b/components/script/dom/gpuadapter.rs
@@ -23,11 +23,13 @@ use dom_struct::dom_struct;
 use js::jsapi::{Heap, JSObject};
 use std::ptr::NonNull;
 use std::rc::Rc;
-use webgpu::{wgpu, WebGPUAdapter, WebGPURequest, WebGPUResponse};
+use webgpu::{wgpu, WebGPU, WebGPUAdapter, WebGPURequest, WebGPUResponse};
 
 #[dom_struct]
 pub struct GPUAdapter {
     reflector_: Reflector,
+    #[ignore_malloc_size_of = "channels are hard"]
+    channel: WebGPU,
     name: DOMString,
     #[ignore_malloc_size_of = "mozjs"]
     extensions: Heap<*mut JSObject>,
@@ -36,12 +38,14 @@ pub struct GPUAdapter {
 
 impl GPUAdapter {
     pub fn new_inherited(
+        channel: WebGPU,
         name: DOMString,
         extensions: Heap<*mut JSObject>,
         adapter: WebGPUAdapter,
     ) -> GPUAdapter {
         GPUAdapter {
             reflector_: Reflector::new(),
+            channel,
             name,
             extensions,
             adapter,
@@ -50,12 +54,15 @@ impl GPUAdapter {
 
     pub fn new(
         global: &GlobalScope,
+        channel: WebGPU,
         name: DOMString,
         extensions: Heap<*mut JSObject>,
         adapter: WebGPUAdapter,
     ) -> DomRoot<GPUAdapter> {
         reflect_dom_object(
-            Box::new(GPUAdapter::new_inherited(name, extensions, adapter)),
+            Box::new(GPUAdapter::new_inherited(
+                channel, name, extensions, adapter,
+            )),
             global,
             GPUAdapterBinding::Wrap,
         )
@@ -89,12 +96,15 @@ impl GPUAdapterMethods for GPUAdapter {
             let id = window
                 .Navigator()
                 .create_device_id(self.adapter.0.backend());
-            match window.webgpu_channel() {
-                Some(thread) => thread
-                    .0
-                    .send(WebGPURequest::RequestDevice(sender, self.adapter, desc, id))
-                    .unwrap(),
-                None => promise.reject_error(Error::Type("No WebGPU thread...".to_owned())),
+            if self
+                .channel
+                .0
+                .send(WebGPURequest::RequestDevice(sender, self.adapter, desc, id))
+                .is_err()
+            {
+                promise.reject_error(Error::Type(
+                    "Failed to send RequestDevice message...".to_owned(),
+                ));
             }
         } else {
             promise.reject_error(Error::Type("No WebGPU thread...".to_owned()))
@@ -109,6 +119,7 @@ impl AsyncWGPUListener for GPUAdapter {
             WebGPUResponse::RequestDevice(device_id, _descriptor) => {
                 let device = GPUDevice::new(
                     &self.global(),
+                    self.channel.clone(),
                     &self,
                     Heap::default(),
                     Heap::default(),
diff --git a/components/script/dom/gpubuffer.rs b/components/script/dom/gpubuffer.rs
index a2a3e3b62eb..160ef6cf79c 100644
--- a/components/script/dom/gpubuffer.rs
+++ b/components/script/dom/gpubuffer.rs
@@ -11,9 +11,8 @@ use crate::dom::bindings::root::DomRoot;
 use crate::dom::bindings::str::DOMString;
 use crate::dom::globalscope::GlobalScope;
 use dom_struct::dom_struct;
-use ipc_channel::ipc::IpcSender;
 use std::cell::Cell;
-use webgpu::{WebGPUBuffer, WebGPUDevice, WebGPURequest};
+use webgpu::{WebGPU, WebGPUBuffer, WebGPUDevice, WebGPURequest};
 
 #[derive(MallocSizeOf)]
 pub enum GPUBufferState {
@@ -26,7 +25,7 @@ pub enum GPUBufferState {
 pub struct GPUBuffer {
     reflector_: Reflector,
     #[ignore_malloc_size_of = "channels are hard"]
-    channel: IpcSender<WebGPURequest>,
+    channel: WebGPU,
     label: DomRefCell<Option<DOMString>>,
     size: GPUBufferSize,
     usage: u32,
@@ -38,7 +37,7 @@ pub struct GPUBuffer {
 
 impl GPUBuffer {
     fn new_inherited(
-        channel: IpcSender<WebGPURequest>,
+        channel: WebGPU,
         buffer: WebGPUBuffer,
         device: WebGPUDevice,
         state: GPUBufferState,
@@ -62,7 +61,7 @@ impl GPUBuffer {
     #[allow(unsafe_code)]
     pub fn new(
         global: &GlobalScope,
-        channel: IpcSender<WebGPURequest>,
+        channel: WebGPU,
         buffer: WebGPUBuffer,
         device: WebGPUDevice,
         state: GPUBufferState,
@@ -90,6 +89,7 @@ impl GPUBufferMethods for GPUBuffer {
     /// https://gpuweb.github.io/gpuweb/#dom-gpubuffer-unmap
     fn Unmap(&self) {
         self.channel
+            .0
             .send(WebGPURequest::UnmapBuffer(self.buffer))
             .unwrap();
     }
@@ -103,6 +103,7 @@ impl GPUBufferMethods for GPUBuffer {
             _ => {},
         };
         self.channel
+            .0
             .send(WebGPURequest::DestroyBuffer(self.buffer))
             .unwrap();
         *self.state.borrow_mut() = GPUBufferState::Destroyed;
diff --git a/components/script/dom/gpudevice.rs b/components/script/dom/gpudevice.rs
index 81974735b55..ba1ea368a5b 100644
--- a/components/script/dom/gpudevice.rs
+++ b/components/script/dom/gpudevice.rs
@@ -25,11 +25,13 @@ use js::jsval::{JSVal, ObjectValue, UndefinedValue};
 use js::typedarray::{ArrayBuffer, CreateWith};
 use std::ptr::{self, NonNull};
 use webgpu::wgpu::resource::{BufferDescriptor, BufferUsage};
-use webgpu::{WebGPUBuffer, WebGPUDevice, WebGPURequest};
+use webgpu::{WebGPU, WebGPUBuffer, WebGPUDevice, WebGPURequest};
 
 #[dom_struct]
 pub struct GPUDevice {
     eventtarget: EventTarget,
+    #[ignore_malloc_size_of = "channels are hard"]
+    channel: WebGPU,
     adapter: Dom<GPUAdapter>,
     #[ignore_malloc_size_of = "mozjs"]
     extensions: Heap<*mut JSObject>,
@@ -41,6 +43,7 @@ pub struct GPUDevice {
 
 impl GPUDevice {
     fn new_inherited(
+        channel: WebGPU,
         adapter: &GPUAdapter,
         extensions: Heap<*mut JSObject>,
         limits: Heap<*mut JSObject>,
@@ -48,6 +51,7 @@ impl GPUDevice {
     ) -> GPUDevice {
         Self {
             eventtarget: EventTarget::new_inherited(),
+            channel,
             adapter: Dom::from_ref(adapter),
             extensions,
             limits,
@@ -59,6 +63,7 @@ impl GPUDevice {
     #[allow(unsafe_code)]
     pub fn new(
         global: &GlobalScope,
+        channel: WebGPU,
         adapter: &GPUAdapter,
         extensions: Heap<*mut JSObject>,
         limits: Heap<*mut JSObject>,
@@ -66,7 +71,7 @@ impl GPUDevice {
     ) -> DomRoot<GPUDevice> {
         reflect_dom_object(
             Box::new(GPUDevice::new_inherited(
-                adapter, extensions, limits, device,
+                channel, adapter, extensions, limits, device,
             )),
             global,
             GPUDeviceBinding::Wrap,
@@ -78,7 +83,6 @@ impl GPUDevice {
     unsafe fn resolve_create_buffer_mapped(
         &self,
         cx: SafeJSContext,
-        channel: ipc_channel::ipc::IpcSender<WebGPURequest>,
         gpu_buffer: WebGPUBuffer,
         array_buffer: Vec<u8>,
         descriptor: BufferDescriptor,
@@ -95,7 +99,7 @@ impl GPUDevice {
 
         let buff = GPUBuffer::new(
             &self.global(),
-            channel,
+            self.channel.clone(),
             gpu_buffer,
             self.device,
             GPUBufferState::Mapped,
@@ -165,25 +169,18 @@ impl GPUDeviceMethods for GPUDevice {
     /// https://gpuweb.github.io/gpuweb/#dom-gpudevice-createbuffer
     fn CreateBuffer(&self, descriptor: &GPUBufferDescriptor) -> DomRoot<GPUBuffer> {
         let (valid, wgpu_descriptor) = self.validate_buffer_descriptor(descriptor);
-        let channel;
         let (sender, receiver) = ipc::channel().unwrap();
         if let Some(window) = self.global().downcast::<Window>() {
             let id = window.Navigator().create_buffer_id(self.device.0.backend());
-            match window.webgpu_channel() {
-                Some(thread) => {
-                    channel = thread.0.clone();
-                    thread
-                        .0
-                        .send(WebGPURequest::CreateBuffer(
-                            sender,
-                            self.device,
-                            id,
-                            wgpu_descriptor,
-                        ))
-                        .unwrap();
-                },
-                None => unimplemented!(),
-            }
+            self.channel
+                .0
+                .send(WebGPURequest::CreateBuffer(
+                    sender,
+                    self.device,
+                    id,
+                    wgpu_descriptor,
+                ))
+                .unwrap();
         } else {
             unimplemented!()
         };
@@ -192,7 +189,7 @@ impl GPUDeviceMethods for GPUDevice {
 
         GPUBuffer::new(
             &self.global(),
-            channel,
+            self.channel.clone(),
             buffer,
             self.device,
             GPUBufferState::Unmapped,
@@ -209,26 +206,19 @@ impl GPUDeviceMethods for GPUDevice {
         descriptor: &GPUBufferDescriptor,
     ) -> Vec<JSVal> {
         let (valid, wgpu_descriptor) = self.validate_buffer_descriptor(descriptor);
-        let channel;
         let (sender, receiver) = ipc::channel().unwrap();
         rooted!(in(*cx) let js_val = UndefinedValue());
         if let Some(window) = self.global().downcast::<Window>() {
             let id = window.Navigator().create_buffer_id(self.device.0.backend());
-            match window.webgpu_channel() {
-                Some(thread) => {
-                    channel = thread.0.clone();
-                    thread
-                        .0
-                        .send(WebGPURequest::CreateBufferMapped(
-                            sender,
-                            self.device,
-                            id,
-                            wgpu_descriptor.clone(),
-                        ))
-                        .unwrap()
-                },
-                None => return vec![js_val.get()],
-            }
+            self.channel
+                .0
+                .send(WebGPURequest::CreateBufferMapped(
+                    sender,
+                    self.device,
+                    id,
+                    wgpu_descriptor.clone(),
+                ))
+                .unwrap()
         } else {
             return vec![js_val.get()];
         };
@@ -236,14 +226,7 @@ impl GPUDeviceMethods for GPUDevice {
         let (buffer, array_buffer) = receiver.recv().unwrap();
 
         unsafe {
-            self.resolve_create_buffer_mapped(
-                cx,
-                channel,
-                buffer,
-                array_buffer,
-                wgpu_descriptor,
-                valid,
-            )
+            self.resolve_create_buffer_mapped(cx, buffer, array_buffer, wgpu_descriptor, valid)
         }
     }
 }
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index d48f16ea662..09b710689bd 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -135,7 +135,6 @@ use style::str::HTML_SPACE_CHARACTERS;
 use style::stylesheets::CssRuleType;
 use style_traits::{CSSPixel, DevicePixel, ParsingMode};
 use url::Position;
-use webgpu::WebGPU;
 use webrender_api::units::{DeviceIntPoint, DeviceIntSize, LayoutPixel};
 use webrender_api::{DocumentId, ExternalScrollId};
 use webvr_traits::WebVRMsg;
@@ -267,10 +266,6 @@ pub struct Window {
     #[ignore_malloc_size_of = "channels are hard"]
     webgl_chan: Option<WebGLChan>,
 
-    #[ignore_malloc_size_of = "channels are hard"]
-    /// A handle for communicating messages to the WebGPU threads.
-    webgpu: Option<WebGPU>,
-
     /// A handle for communicating messages to the webvr thread, if available.
     #[ignore_malloc_size_of = "channels are hard"]
     webvr_chan: Option<IpcSender<WebVRMsg>>,
@@ -466,10 +461,6 @@ impl Window {
             .map(|chan| WebGLCommandSender::new(chan.clone(), self.get_event_loop_waker()))
     }
 
-    pub fn webgpu_channel(&self) -> Option<WebGPU> {
-        self.webgpu.clone()
-    }
-
     pub fn webvr_thread(&self) -> Option<IpcSender<WebVRMsg>> {
         self.webvr_chan.clone()
     }
@@ -2213,7 +2204,6 @@ impl Window {
         navigation_start: u64,
         navigation_start_precise: u64,
         webgl_chan: Option<WebGLChan>,
-        webgpu: Option<WebGPU>,
         webvr_chan: Option<IpcSender<WebVRMsg>>,
         webxr_registry: webxr_api::Registry,
         microtask_queue: Rc<MicrotaskQueue>,
@@ -2292,7 +2282,6 @@ impl Window {
             media_query_lists: DOMTracker::new(),
             test_runner: Default::default(),
             webgl_chan,
-            webgpu,
             webvr_chan,
             webxr_registry,
             permission_state_invocation_results: Default::default(),
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index f5397d8cce5..9ce99c26441 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -164,7 +164,6 @@ use style::dom::OpaqueNode;
 use style::thread_state::{self, ThreadState};
 use time::{at_utc, get_time, precise_time_ns, Timespec};
 use url::Position;
-use webgpu::WebGPU;
 use webrender_api::units::LayoutPixel;
 use webrender_api::DocumentId;
 use webvr_traits::{WebVREvent, WebVRMsg};
@@ -630,9 +629,6 @@ pub struct ScriptThread {
     /// A handle to the WebGL thread
     webgl_chan: Option<WebGLPipeline>,
 
-    /// A handle to the WebGPU threads
-    webgpu: Option<WebGPU>,
-
     /// A handle to the webvr thread, if available
     webvr_chan: Option<IpcSender<WebVRMsg>>,
 
@@ -1339,7 +1335,6 @@ impl ScriptThread {
             layout_to_constellation_chan: state.layout_to_constellation_chan,
 
             webgl_chan: state.webgl_chan,
-            webgpu: state.webgpu,
             webvr_chan: state.webvr_chan,
             webxr_registry: state.webxr_registry,
 
@@ -3201,7 +3196,6 @@ impl ScriptThread {
             incomplete.navigation_start,
             incomplete.navigation_start_precise,
             self.webgl_chan.as_ref().map(|chan| chan.channel()),
-            self.webgpu.clone(),
             self.webvr_chan.clone(),
             self.webxr_registry.clone(),
             self.microtask_queue.clone(),
diff --git a/components/script_traits/Cargo.toml b/components/script_traits/Cargo.toml
index 0635d99dda3..6b540a98c2b 100644
--- a/components/script_traits/Cargo.toml
+++ b/components/script_traits/Cargo.toml
@@ -36,6 +36,7 @@ profile_traits = {path = "../profile_traits"}
 serde = "1.0"
 servo_atoms = {path = "../atoms"}
 servo_url = {path = "../url"}
+smallvec = "0.6"
 style_traits = {path = "../style_traits", features = ["servo"]}
 time = "0.1.12"
 url = "2.0"
diff --git a/components/script_traits/lib.rs b/components/script_traits/lib.rs
index 8e6b89e12f9..d2d37e5c32a 100644
--- a/components/script_traits/lib.rs
+++ b/components/script_traits/lib.rs
@@ -65,7 +65,6 @@ use std::sync::Arc;
 use std::time::Duration;
 use style_traits::CSSPixel;
 use style_traits::SpeculativePainter;
-use webgpu::WebGPU;
 use webrender_api::units::{
     DeviceIntSize, DevicePixel, LayoutPixel, LayoutPoint, LayoutSize, WorldPoint,
 };
@@ -665,8 +664,6 @@ pub struct InitialScriptState {
     pub content_process_shutdown_chan: Sender<()>,
     /// A channel to the WebGL thread used in this pipeline.
     pub webgl_chan: Option<WebGLPipeline>,
-    /// A channel to the WebGPU threads.
-    pub webgpu: Option<WebGPU>,
     /// A channel to the webvr thread, if available.
     pub webvr_chan: Option<IpcSender<WebVRMsg>>,
     /// The XR device registry
diff --git a/components/script_traits/script_msg.rs b/components/script_traits/script_msg.rs
index 1eccc794398..8a04b59d57d 100644
--- a/components/script_traits/script_msg.rs
+++ b/components/script_traits/script_msg.rs
@@ -30,10 +30,12 @@ use net_traits::storage_thread::StorageType;
 use net_traits::CoreResourceMsg;
 use servo_url::ImmutableOrigin;
 use servo_url::ServoUrl;
+use smallvec::SmallVec;
 use std::collections::{HashMap, VecDeque};
 use std::fmt;
 use style_traits::viewport::ViewportConstraints;
 use style_traits::CSSPixel;
+use webgpu::{wgpu, WebGPUResponseResult};
 use webrender_api::units::{DeviceIntPoint, DeviceIntSize};
 
 /// A particular iframe's size, associated with a browsing context.
@@ -257,6 +259,12 @@ pub enum ScriptMsg {
     /// Notifies the constellation about media session events
     /// (i.e. when there is metadata for the active media session, playback state changes...).
     MediaSessionEvent(PipelineId, MediaSessionEvent),
+    /// Create a WebGPU Adapter instance
+    RequestAdapter(
+        IpcSender<WebGPUResponseResult>,
+        wgpu::instance::RequestAdapterOptions,
+        SmallVec<[wgpu::id::AdapterId; 4]>,
+    ),
 }
 
 impl fmt::Debug for ScriptMsg {
@@ -309,6 +317,7 @@ impl fmt::Debug for ScriptMsg {
             GetScreenSize(..) => "GetScreenSize",
             GetScreenAvailSize(..) => "GetScreenAvailSize",
             MediaSessionEvent(..) => "MediaSessionEvent",
+            RequestAdapter(..) => "RequestAdapter",
         };
         write!(formatter, "ScriptMsg::{}", variant)
     }
diff --git a/components/servo/lib.rs b/components/servo/lib.rs
index ad82066c3df..2ae1908f8bb 100644
--- a/components/servo/lib.rs
+++ b/components/servo/lib.rs
@@ -874,8 +874,6 @@ fn create_constellation(
 
     let resource_sender = public_resource_threads.sender();
 
-    let webgpu = webgpu::WebGPU::new();
-
     let initial_state = InitialConstellationState {
         compositor_proxy,
         embedder_proxy,
@@ -890,7 +888,6 @@ fn create_constellation(
         webrender_document,
         webrender_api_sender,
         webgl_threads,
-        webgpu,
         webvr_chan,
         webxr_registry,
         glplayer_threads,
diff --git a/components/webgpu/lib.rs b/components/webgpu/lib.rs
index 156beeb040b..8ad053460bb 100644
--- a/components/webgpu/lib.rs
+++ b/components/webgpu/lib.rs
@@ -16,7 +16,7 @@ use smallvec::SmallVec;
 
 #[derive(Debug, Deserialize, Serialize)]
 pub enum WebGPUResponse {
-    RequestAdapter(String, WebGPUAdapter),
+    RequestAdapter(String, WebGPUAdapter, WebGPU),
     RequestDevice(WebGPUDevice, wgpu::instance::DeviceDescriptor),
 }
 
@@ -70,11 +70,12 @@ impl WebGPU {
                 return None;
             },
         };
+        let sender_clone = sender.clone();
 
         if let Err(e) = std::thread::Builder::new()
             .name("WGPU".to_owned())
             .spawn(move || {
-                WGPU::new(receiver).run();
+                WGPU::new(receiver, sender_clone).run();
             })
         {
             warn!("Failed to spwan WGPU thread ({})", e);
@@ -92,6 +93,7 @@ impl WebGPU {
 
 struct WGPU {
     receiver: IpcReceiver<WebGPURequest>,
+    sender: IpcSender<WebGPURequest>,
     global: wgpu::hub::Global<()>,
     adapters: Vec<WebGPUAdapter>,
     devices: Vec<WebGPUDevice>,
@@ -100,9 +102,10 @@ struct WGPU {
 }
 
 impl WGPU {
-    fn new(receiver: IpcReceiver<WebGPURequest>) -> Self {
+    fn new(receiver: IpcReceiver<WebGPURequest>, sender: IpcSender<WebGPURequest>) -> Self {
         WGPU {
             receiver,
+            sender,
             global: wgpu::hub::Global::new("wgpu-core"),
             adapters: Vec::new(),
             devices: Vec::new(),
@@ -118,30 +121,41 @@ impl WGPU {
         while let Ok(msg) = self.receiver.recv() {
             match msg {
                 WebGPURequest::RequestAdapter(sender, options, ids) => {
-                    let adapter_id = match self.global.pick_adapter(
-                        &options,
-                        wgpu::instance::AdapterInputs::IdSet(&ids, |id| id.backend()),
-                    ) {
-                        Some(id) => id,
-                        None => {
-                            if let Err(e) =
-                                sender.send(Err("Failed to get webgpu adapter".to_string()))
-                            {
-                                warn!(
-                                    "Failed to send response to WebGPURequest::RequestAdapter ({})",
-                                    e
-                                )
-                            }
-                            return;
-                        },
+                    let adapter_id = if let Some(pos) = self
+                        .adapters
+                        .iter()
+                        .position(|adapter| ids.contains(&adapter.0))
+                    {
+                        self.adapters[pos].0
+                    } else {
+                        let adapter_id = match self.global.pick_adapter(
+                            &options,
+                            wgpu::instance::AdapterInputs::IdSet(&ids, |id| id.backend()),
+                        ) {
+                            Some(id) => id,
+                            None => {
+                                if let Err(e) =
+                                    sender.send(Err("Failed to get webgpu adapter".to_string()))
+                                {
+                                    warn!(
+                                        "Failed to send response to WebGPURequest::RequestAdapter ({})",
+                                        e
+                                    )
+                                }
+                                return;
+                            },
+                        };
+                        adapter_id
                     };
                     let adapter = WebGPUAdapter(adapter_id);
                     self.adapters.push(adapter);
                     let global = &self.global;
                     let info = gfx_select!(adapter_id => global.adapter_get_info(adapter_id));
-                    if let Err(e) =
-                        sender.send(Ok(WebGPUResponse::RequestAdapter(info.name, adapter)))
-                    {
+                    if let Err(e) = sender.send(Ok(WebGPUResponse::RequestAdapter(
+                        info.name,
+                        adapter,
+                        WebGPU(self.sender.clone()),
+                    ))) {
                         warn!(
                             "Failed to send response to WebGPURequest::RequestAdapter ({})",
                             e