[core] Make the BackgroundScheduler a singleton

- Do not carry it over everywhere as parameter, it is a shared
  instance anyway and the lifecycle is pretty much the app lifecycle
  from the moment we instantiate a map.
- Rename to BackgroundScheduler because it is a Scheduler that will
  do tasks in the background, we don't make assumptions if it is a
  thread pool or a single thread.
- Most importantly, remove the dependency from `core` on `platform`.

31 files changed, 47 insertions, 218 deletions

diff --git a/platform/android/core-files.json b/platform/android/core-files.json
index 20dcc12c7d..ba56695bdd 100644
--- a/platform/android/core-files.json
+++ b/platform/android/core-files.json
@@ -89,9 +89,7 @@
         "platform/default/src/mbgl/gl/headless_frontend.cpp",
         "platform/default/src/mbgl/map/map_snapshotter.cpp",
         "platform/default/src/mbgl/text/bidi.cpp",
-        "platform/default/src/mbgl/util/default_thread_pool.cpp",
         "platform/default/src/mbgl/util/png_writer.cpp",
-        "platform/default/src/mbgl/util/shared_thread_pool.cpp",
         "platform/default/src/mbgl/util/thread_local.cpp",
         "platform/default/src/mbgl/util/utf.cpp",
         "platform/linux/src/headless_backend_egl.cpp"
@@ -101,9 +99,7 @@
         "mbgl/gl/headless_backend.hpp": "platform/default/include/mbgl/gl/headless_backend.hpp",
         "mbgl/gl/headless_frontend.hpp": "platform/default/include/mbgl/gl/headless_frontend.hpp",
         "mbgl/map/map_snapshotter.hpp": "platform/default/include/mbgl/map/map_snapshotter.hpp",
-        "mbgl/text/unaccent.hpp": "platform/default/include/mbgl/text/unaccent.hpp",
-        "mbgl/util/default_thread_pool.hpp": "platform/default/include/mbgl/util/default_thread_pool.hpp",
-        "mbgl/util/shared_thread_pool.hpp": "platform/default/include/mbgl/util/shared_thread_pool.hpp"
+        "mbgl/text/unaccent.hpp": "platform/default/include/mbgl/text/unaccent.hpp"
     },
     "private_headers": {
         "android_renderer_backend.hpp": "platform/android/src/android_renderer_backend.hpp",
diff --git a/platform/android/src/map_renderer.cpp b/platform/android/src/map_renderer.cpp
index 64c00585f8..92444c404d 100644
--- a/platform/android/src/map_renderer.cpp
+++ b/platform/android/src/map_renderer.cpp
@@ -2,7 +2,6 @@
 
 #include <mbgl/renderer/renderer.hpp>
 #include <mbgl/gfx/backend_scope.hpp>
-#include <mbgl/util/shared_thread_pool.hpp>
 #include <mbgl/util/run_loop.hpp>
 
 #include <string>
@@ -23,7 +22,6 @@ MapRenderer::MapRenderer(jni::JNIEnv& _env,
         , pixelRatio(pixelRatio_)
         , programCacheDir(jni::Make<std::string>(_env, programCacheDir_))
         , localIdeographFontFamily(localIdeographFontFamily_ ? jni::Make<std::string>(_env, localIdeographFontFamily_) : optional<std::string>{})
-        , threadPool(sharedThreadPool())
         , mailbox(std::make_shared<Mailbox>(*this)) {
 }
 
@@ -175,7 +173,7 @@ void MapRenderer::onSurfaceCreated(JNIEnv&) {
 
     // Create the new backend and renderer
     backend = std::make_unique<AndroidRendererBackend>();
-    renderer = std::make_unique<Renderer>(*backend, pixelRatio, *threadPool, programCacheDir, localIdeographFontFamily);
+    renderer = std::make_unique<Renderer>(*backend, pixelRatio, programCacheDir, localIdeographFontFamily);
     rendererRef = std::make_unique<ActorRef<Renderer>>(*renderer, mailbox);
 
     // Set the observer on the new Renderer implementation
diff --git a/platform/android/src/native_map_view.cpp b/platform/android/src/native_map_view.cpp
index 8f1ec9c576..ae53bcc802 100755
--- a/platform/android/src/native_map_view.cpp
+++ b/platform/android/src/native_map_view.cpp
@@ -21,7 +21,6 @@
 #include <mbgl/util/exception.hpp>
 #include <mbgl/util/geo.hpp>
 #include <mbgl/util/image.hpp>
-#include <mbgl/util/shared_thread_pool.hpp>
 #include <mbgl/util/logging.hpp>
 #include <mbgl/util/platform.hpp>
 #include <mbgl/util/projection.hpp>
@@ -66,8 +65,7 @@ NativeMapView::NativeMapView(jni::JNIEnv& _env,
                              jni::jboolean _crossSourceCollisions)
     : javaPeer(_env, _obj)
     , mapRenderer(MapRenderer::getNativePeer(_env, jMapRenderer))
-    , pixelRatio(_pixelRatio)
-    , threadPool(sharedThreadPool()) {
+    , pixelRatio(_pixelRatio) {
 
     // Get a reference to the JavaVM for callbacks
     if (_env.GetJavaVM(&vm) < 0) {
@@ -89,7 +87,7 @@ NativeMapView::NativeMapView(jni::JNIEnv& _env,
 
     // Create the core map
     map = std::make_unique<mbgl::Map>(
-        *rendererFrontend, *this, *threadPool, options,
+        *rendererFrontend, *this, options,
         mbgl::android::FileSource::getSharedResourceOptions(_env, jFileSource));
 }
 
diff --git a/platform/android/src/native_map_view.hpp b/platform/android/src/native_map_view.hpp
index c9ba6089c3..9e6ad73dd7 100755
--- a/platform/android/src/native_map_view.hpp
+++ b/platform/android/src/native_map_view.hpp
@@ -4,7 +4,6 @@
 #include <mbgl/map/camera.hpp>
 #include <mbgl/map/map.hpp>
 #include <mbgl/util/noncopyable.hpp>
-#include <mbgl/util/default_thread_pool.hpp>
 #include <mbgl/util/run_loop.hpp>
 #include <mbgl/storage/network_status.hpp>
 
@@ -258,7 +257,6 @@ private:
     int height = 64;
 
     // Ensure these are initialised last
-    std::shared_ptr<mbgl::ThreadPool> threadPool;
     std::unique_ptr<mbgl::Map> map;
     mbgl::EdgeInsets insets;
 };
diff --git a/platform/android/src/snapshotter/map_snapshotter.cpp b/platform/android/src/snapshotter/map_snapshotter.cpp
index 47a2781cb5..2eca6595e1 100644
--- a/platform/android/src/snapshotter/map_snapshotter.cpp
+++ b/platform/android/src/snapshotter/map_snapshotter.cpp
@@ -2,7 +2,6 @@
 
 #include <mbgl/renderer/renderer.hpp>
 #include <mbgl/style/style.hpp>
-#include <mbgl/util/shared_thread_pool.hpp>
 #include <mbgl/util/logging.hpp>
 #include <mbgl/util/string.hpp>
 #include <mbgl/actor/scheduler.hpp>
@@ -27,8 +26,7 @@ MapSnapshotter::MapSnapshotter(jni::JNIEnv& _env,
                                const jni::String& _programCacheDir,
                                const jni::String& _localIdeographFontFamily)
         : javaPeer(_env, _obj)
-        , pixelRatio(_pixelRatio)
-        , threadPool(sharedThreadPool()) {
+        , pixelRatio(_pixelRatio) {
 
     // Get a reference to the JavaVM for callbacks
     if (_env.GetJavaVM(&vm) < 0) {
@@ -58,8 +56,7 @@ MapSnapshotter::MapSnapshotter(jni::JNIEnv& _env,
 
     showLogo = _showLogo;
     // Create the core snapshotter
-    snapshotter = std::make_unique<mbgl::MapSnapshotter>(threadPool,
-                                                         style,
+    snapshotter = std::make_unique<mbgl::MapSnapshotter>(style,
                                                          size,
                                                          pixelRatio,
                                                          cameraOptions,
diff --git a/platform/android/src/snapshotter/map_snapshotter.hpp b/platform/android/src/snapshotter/map_snapshotter.hpp
index e8c0885ff1..791aa61d6a 100644
--- a/platform/android/src/snapshotter/map_snapshotter.hpp
+++ b/platform/android/src/snapshotter/map_snapshotter.hpp
@@ -1,7 +1,6 @@
 #pragma once
 
 #include <mbgl/map/map_snapshotter.hpp>
-#include <mbgl/util/default_thread_pool.hpp>
 #include <mbgl/util/util.hpp>
 
 #include "../file_source.hpp"
@@ -63,7 +62,6 @@ private:
     float pixelRatio;
     bool showLogo;
 
-    std::shared_ptr<mbgl::ThreadPool> threadPool;
     std::unique_ptr<Actor<mbgl::MapSnapshotter::Callback>> snapshotCallback;
     std::unique_ptr<mbgl::MapSnapshotter> snapshotter;
 
diff --git a/platform/android/src/style/sources/geojson_source.cpp b/platform/android/src/style/sources/geojson_source.cpp
index a9307afe67..5ff4864275 100644
--- a/platform/android/src/style/sources/geojson_source.cpp
+++ b/platform/android/src/style/sources/geojson_source.cpp
@@ -17,7 +17,6 @@
 #include "../conversion/url_or_tileset.hpp"
 
 #include <string>
-#include <mbgl/util/shared_thread_pool.hpp>
 
 // GeoJSONSource uses a "coalescing" model for high frequency asynchronous data update calls,
 // which in practice means, that any update that started processing is going to finish
@@ -48,16 +47,14 @@ namespace android {
         : Source(env, std::make_unique<mbgl::style::GeoJSONSource>(
                 jni::Make<std::string>(env, sourceId),
                 convertGeoJSONOptions(env, options)))
-        , threadPool(sharedThreadPool())
-        , converter(std::make_unique<Actor<FeatureConverter>>(*threadPool)) {
+        , converter(std::make_unique<Actor<FeatureConverter>>(Scheduler::GetBackground())) {
     }
 
     GeoJSONSource::GeoJSONSource(jni::JNIEnv& env,
                                  mbgl::style::Source& coreSource,
                                  AndroidRendererFrontend& frontend)
         : Source(env, coreSource, createJavaPeer(env), frontend)
-        , threadPool(sharedThreadPool())
-        , converter(std::make_unique<Actor<FeatureConverter>>(*threadPool)) {
+        , converter(std::make_unique<Actor<FeatureConverter>>(Scheduler::GetBackground())) {
     }
 
     GeoJSONSource::~GeoJSONSource() = default;
diff --git a/platform/darwin/src/MGLMapSnapshotter.mm b/platform/darwin/src/MGLMapSnapshotter.mm
index 171f24e4d0..65bed2cf42 100644
--- a/platform/darwin/src/MGLMapSnapshotter.mm
+++ b/platform/darwin/src/MGLMapSnapshotter.mm
@@ -8,9 +8,7 @@
 #import <mbgl/map/camera.hpp>
 #import <mbgl/storage/resource_options.hpp>
 #import <mbgl/storage/default_file_source.hpp>
-#import <mbgl/util/default_thread_pool.hpp>
 #import <mbgl/util/string.hpp>
-#import <mbgl/util/shared_thread_pool.hpp>
 
 #import "MGLOfflineStorage_Private.h"
 #import "MGLGeometry_Private.h"
@@ -125,7 +123,6 @@ const CGFloat MGLSnapshotterMinimumPixelSize = 64;
 @end
 
 @implementation MGLMapSnapshotter {
-    std::shared_ptr<mbgl::ThreadPool> _mbglThreadPool;
     std::unique_ptr<mbgl::MapSnapshotter> _mbglMapSnapshotter;
     std::unique_ptr<mbgl::Actor<mbgl::MapSnapshotter::Callback>> _snapshotCallback;
 }
@@ -176,7 +173,6 @@ const CGFloat MGLSnapshotterMinimumPixelSize = 64;
 
     _mbglMapSnapshotter.reset();
     _snapshotCallback.reset();
-    _mbglThreadPool.reset();
     
     self.terminated = YES;
 }
@@ -591,8 +587,6 @@ const CGFloat MGLSnapshotterMinimumPixelSize = 64;
     _options = options;
 
     auto mbglFileSource = [[MGLOfflineStorage sharedOfflineStorage] mbglFileSource];
-
-    _mbglThreadPool = mbgl::sharedThreadPool();
     
     std::string styleURL = std::string([options.styleURL.absoluteString UTF8String]);
     std::pair<bool, std::string> style = std::make_pair(false, styleURL);
@@ -630,7 +624,7 @@ const CGFloat MGLSnapshotterMinimumPixelSize = 64;
 
     // Create the snapshotter
     _mbglMapSnapshotter = std::make_unique<mbgl::MapSnapshotter>(
-        _mbglThreadPool, style, size, pixelRatio, cameraOptions, coordinateBounds, config.cacheDir, config.localFontFamilyName, resourceOptions);
+        style, size, pixelRatio, cameraOptions, coordinateBounds, config.cacheDir, config.localFontFamilyName, resourceOptions);
 }
 
 @end
diff --git a/platform/default/include/mbgl/gl/headless_frontend.hpp b/platform/default/include/mbgl/gl/headless_frontend.hpp
index ff733f423d..1e693bdef1 100644
--- a/platform/default/include/mbgl/gl/headless_frontend.hpp
+++ b/platform/default/include/mbgl/gl/headless_frontend.hpp
@@ -10,7 +10,6 @@
 
 namespace mbgl {
 
-class Scheduler;
 class Renderer;
 class Map;
 class TransformState;
@@ -22,13 +21,11 @@ class RendererBackend;
 class HeadlessFrontend : public RendererFrontend {
 public:
     HeadlessFrontend(float pixelRatio_,
-                     Scheduler&,
                      const optional<std::string> programCacheDir = {},
                      gfx::ContextMode mode = gfx::ContextMode::Unique,
                      const optional<std::string> localFontFamily = {});
     HeadlessFrontend(Size,
                      float pixelRatio_,
-                     Scheduler&,
                      const optional<std::string> programCacheDir = {},
                      gfx::ContextMode mode = gfx::ContextMode::Unique,
                      const optional<std::string> localFontFamily = {});
diff --git a/platform/default/include/mbgl/map/map_snapshotter.hpp b/platform/default/include/mbgl/map/map_snapshotter.hpp
index ccc3ee17f7..db1ba1f267 100644
--- a/platform/default/include/mbgl/map/map_snapshotter.hpp
+++ b/platform/default/include/mbgl/map/map_snapshotter.hpp
@@ -26,8 +26,7 @@ class Style;
 
 class MapSnapshotter {
 public:
-    MapSnapshotter(std::shared_ptr<Scheduler> scheduler,
-                   const std::pair<bool, std::string> style,
+    MapSnapshotter(const std::pair<bool, std::string> style,
                    const Size&,
                    const float pixelRatio,
                    const optional<CameraOptions> cameraOptions,
diff --git a/platform/default/include/mbgl/util/default_thread_pool.hpp b/platform/default/include/mbgl/util/default_thread_pool.hpp
deleted file mode 100644
index a14d16d771..0000000000
--- a/platform/default/include/mbgl/util/default_thread_pool.hpp
+++ /dev/null
@@ -1,27 +0,0 @@
-#pragma once
-
-#include <mbgl/actor/scheduler.hpp>
-
-#include <condition_variable>
-#include <mutex>
-#include <queue>
-#include <thread>
-
-namespace mbgl {
-
-class ThreadPool : public Scheduler {
-public:
-    ThreadPool(std::size_t count);
-    ~ThreadPool() override;
-
-    void schedule(std::weak_ptr<Mailbox>) override;
-
-private:
-    std::vector<std::thread> threads;
-    std::queue<std::weak_ptr<Mailbox>> queue;
-    std::mutex mutex;
-    std::condition_variable cv;
-    bool terminate { false };
-};
-
-} // namespace mbgl
diff --git a/platform/default/include/mbgl/util/shared_thread_pool.hpp b/platform/default/include/mbgl/util/shared_thread_pool.hpp
deleted file mode 100644
index 04a3cb58d5..0000000000
--- a/platform/default/include/mbgl/util/shared_thread_pool.hpp
+++ /dev/null
@@ -1,9 +0,0 @@
-#pragma once
-
-#include <mbgl/util/default_thread_pool.hpp>
-
-namespace mbgl {
-
-std::shared_ptr<ThreadPool> sharedThreadPool();
-
-} // namespace mbgl
diff --git a/platform/default/src/mbgl/gl/headless_frontend.cpp b/platform/default/src/mbgl/gl/headless_frontend.cpp
index 7e56996f63..101028b5c8 100644
--- a/platform/default/src/mbgl/gl/headless_frontend.cpp
+++ b/platform/default/src/mbgl/gl/headless_frontend.cpp
@@ -10,17 +10,15 @@
 namespace mbgl {
 
 HeadlessFrontend::HeadlessFrontend(float pixelRatio_,
-                                   Scheduler& scheduler,
                                    const optional<std::string> programCacheDir,
                                    const gfx::ContextMode contextMode,
                                    const optional<std::string> localFontFamily)
     : HeadlessFrontend(
-          { 256, 256 }, pixelRatio_, scheduler, programCacheDir, contextMode, localFontFamily) {
+          { 256, 256 }, pixelRatio_, programCacheDir, contextMode, localFontFamily) {
 }
 
 HeadlessFrontend::HeadlessFrontend(Size size_,
                                    float pixelRatio_,
-                                   Scheduler& scheduler,
                                    const optional<std::string> programCacheDir,
                                    const gfx::ContextMode contextMode,
                                    const optional<std::string> localFontFamily)
@@ -40,7 +38,7 @@ HeadlessFrontend::HeadlessFrontend(Size size_,
             renderer->render(*updateParameters_);
         }
     }),
-    renderer(std::make_unique<Renderer>(backend, pixelRatio, scheduler, programCacheDir, localFontFamily)) {
+    renderer(std::make_unique<Renderer>(backend, pixelRatio, programCacheDir, localFontFamily)) {
 }
 
 HeadlessFrontend::~HeadlessFrontend() = default;
diff --git a/platform/default/src/mbgl/map/map_snapshotter.cpp b/platform/default/src/mbgl/map/map_snapshotter.cpp
index 6e02ac8532..7bfa2462a0 100644
--- a/platform/default/src/mbgl/map/map_snapshotter.cpp
+++ b/platform/default/src/mbgl/map/map_snapshotter.cpp
@@ -14,8 +14,7 @@ namespace mbgl {
 
 class MapSnapshotter::Impl {
 public:
-    Impl(std::shared_ptr<Scheduler>,
-         const std::pair<bool, std::string> style,
+    Impl(const std::pair<bool, std::string> style,
          const Size&,
          const float pixelRatio,
          const optional<CameraOptions> cameraOptions,
@@ -42,13 +41,11 @@ public:
     void snapshot(ActorRef<MapSnapshotter::Callback>);
 
 private:
-    std::shared_ptr<Scheduler> scheduler;
     HeadlessFrontend frontend;
     Map map;
 };
 
-MapSnapshotter::Impl::Impl(std::shared_ptr<Scheduler> scheduler_,
-                           const std::pair<bool, std::string> style,
+MapSnapshotter::Impl::Impl(const std::pair<bool, std::string> style,
                            const Size& size,
                            const float pixelRatio,
                            const optional<CameraOptions> cameraOptions,
@@ -56,12 +53,10 @@ MapSnapshotter::Impl::Impl(std::shared_ptr<Scheduler> scheduler_,
                            const optional<std::string> programCacheDir,
                            const optional<std::string> localFontFamily,
                            const ResourceOptions& resourceOptions)
-    : scheduler(std::move(scheduler_)),
-      frontend(
-          size, pixelRatio, *scheduler, programCacheDir, gfx::ContextMode::Unique, localFontFamily),
+     : frontend(
+          size, pixelRatio, programCacheDir, gfx::ContextMode::Unique, localFontFamily),
       map(frontend,
           MapObserver::nullObserver(),
-          *scheduler,
           MapOptions().withMapMode(MapMode::Static).withSize(size).withPixelRatio(pixelRatio),
           resourceOptions) {
     if (style.first) {
@@ -168,8 +163,7 @@ LatLngBounds MapSnapshotter::Impl::getRegion() const {
     return map.latLngBoundsForCamera(getCameraOptions());
 }
 
-MapSnapshotter::MapSnapshotter(std::shared_ptr<Scheduler> scheduler,
-                               const std::pair<bool, std::string> style,
+MapSnapshotter::MapSnapshotter(const std::pair<bool, std::string> style,
                                const Size& size,
                                const float pixelRatio,
                                const optional<CameraOptions> cameraOptions,
@@ -178,7 +172,7 @@ MapSnapshotter::MapSnapshotter(std::shared_ptr<Scheduler> scheduler,
                                const optional<std::string> localFontFamily,
                                const ResourceOptions& resourceOptions)
    : impl(std::make_unique<util::Thread<MapSnapshotter::Impl>>(
-       "Map Snapshotter", std::move(scheduler), style, size, pixelRatio, cameraOptions,
+       "Map Snapshotter", style, size, pixelRatio, cameraOptions,
        region, programCacheDir, localFontFamily, resourceOptions.clone())) {}
 
 MapSnapshotter::~MapSnapshotter() = default;
diff --git a/platform/default/src/mbgl/util/default_thread_pool.cpp b/platform/default/src/mbgl/util/default_thread_pool.cpp
deleted file mode 100644
index d3950bb8aa..0000000000
--- a/platform/default/src/mbgl/util/default_thread_pool.cpp
+++ /dev/null
@@ -1,57 +0,0 @@
-#include <mbgl/util/default_thread_pool.hpp>
-#include <mbgl/actor/mailbox.hpp>
-#include <mbgl/util/platform.hpp>
-#include <mbgl/util/string.hpp>
-
-namespace mbgl {
-
-ThreadPool::ThreadPool(std::size_t count) {
-    threads.reserve(count);
-    for (std::size_t i = 0; i < count; ++i) {
-        threads.emplace_back([this, i]() {
-            platform::setCurrentThreadName(std::string{ "Worker " } + util::toString(i + 1));
-
-            while (true) {
-                std::unique_lock<std::mutex> lock(mutex);
-
-                cv.wait(lock, [this] {
-                    return !queue.empty() || terminate;
-                });
-
-                if (terminate) {
-                    return;
-                }
-
-                auto mailbox = queue.front();
-                queue.pop();
-                lock.unlock();
-
-                Mailbox::maybeReceive(mailbox);
-            }
-        });
-    }
-}
-
-ThreadPool::~ThreadPool() {
-    {
-        std::lock_guard<std::mutex> lock(mutex);
-        terminate = true;
-    }
-
-    cv.notify_all();
-
-    for (auto& thread : threads) {
-        thread.join();
-    }
-}
-
-void ThreadPool::schedule(std::weak_ptr<Mailbox> mailbox) {
-    {
-        std::lock_guard<std::mutex> lock(mutex);
-        queue.push(mailbox);
-    }
-
-    cv.notify_one();
-}
-
-} // namespace mbgl
diff --git a/platform/default/src/mbgl/util/shared_thread_pool.cpp b/platform/default/src/mbgl/util/shared_thread_pool.cpp
deleted file mode 100644
index d7facbab94..0000000000
--- a/platform/default/src/mbgl/util/shared_thread_pool.cpp
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <mbgl/util/shared_thread_pool.hpp>
-
-namespace mbgl {
-
-std::shared_ptr<ThreadPool> sharedThreadPool() {
-    static std::weak_ptr<ThreadPool> weak;
-    auto pool = weak.lock();
-    if (!pool) {
-        weak = pool = std::make_shared<ThreadPool>(4);
-    }
-    return pool;
-}
-
-} // namespace mbgl
diff --git a/platform/glfw/main.cpp b/platform/glfw/main.cpp
index 4e631ec895..04cff3962a 100644
--- a/platform/glfw/main.cpp
+++ b/platform/glfw/main.cpp
@@ -5,7 +5,6 @@
 #include <mbgl/util/default_styles.hpp>
 #include <mbgl/util/logging.hpp>
 #include <mbgl/util/platform.hpp>
-#include <mbgl/util/default_thread_pool.hpp>
 #include <mbgl/util/string.hpp>
 #include <mbgl/storage/default_file_source.hpp>
 #include <mbgl/style/style.hpp>
@@ -109,10 +108,9 @@ int main(int argc, char *argv[]) {
         mbgl::Log::Warning(mbgl::Event::Setup, "Application is offline. Press `O` to toggle online status.");
     }
 
-    mbgl::ThreadPool threadPool(4);
-    GLFWRendererFrontend rendererFrontend { std::make_unique<mbgl::Renderer>(view->getRendererBackend(), view->getPixelRatio(), threadPool), *view };
+    GLFWRendererFrontend rendererFrontend { std::make_unique<mbgl::Renderer>(view->getRendererBackend(), view->getPixelRatio()), *view };
 
-    mbgl::Map map(rendererFrontend, *view, threadPool,
+    mbgl::Map map(rendererFrontend, *view,
                   mbgl::MapOptions().withSize(view->getSize()).withPixelRatio(view->getPixelRatio()), resourceOptions);
 
     backend.setMap(&map);
@@ -199,5 +197,6 @@ int main(int argc, char *argv[]) {
                     settings.latitude, settings.longitude, settings.zoom, settings.bearing);
 
     view = nullptr;
+
     return 0;
 }
diff --git a/platform/ios/core-files.json b/platform/ios/core-files.json
index c3e54a45b0..98833b0c94 100644
--- a/platform/ios/core-files.json
+++ b/platform/ios/core-files.json
@@ -14,9 +14,7 @@
         "platform/default/src/mbgl/gl/headless_frontend.cpp",
         "platform/default/src/mbgl/map/map_snapshotter.cpp",
         "platform/default/src/mbgl/text/bidi.cpp",
-        "platform/default/src/mbgl/util/default_thread_pool.cpp",
         "platform/default/src/mbgl/util/png_writer.cpp",
-        "platform/default/src/mbgl/util/shared_thread_pool.cpp",
         "platform/default/src/mbgl/util/thread_local.cpp",
         "platform/default/src/mbgl/util/utf.cpp"
     ],
@@ -26,9 +24,7 @@
         "mbgl/gl/headless_backend.hpp": "platform/default/include/mbgl/gl/headless_backend.hpp",
         "mbgl/gl/headless_frontend.hpp": "platform/default/include/mbgl/gl/headless_frontend.hpp",
         "mbgl/map/map_snapshotter.hpp": "platform/default/include/mbgl/map/map_snapshotter.hpp",
-        "mbgl/util/default_styles.hpp": "platform/default/include/mbgl/util/default_styles.hpp",
-        "mbgl/util/default_thread_pool.hpp": "platform/default/include/mbgl/util/default_thread_pool.hpp",
-        "mbgl/util/shared_thread_pool.hpp": "platform/default/include/mbgl/util/shared_thread_pool.hpp"
+        "mbgl/util/default_styles.hpp": "platform/default/include/mbgl/util/default_styles.hpp"
     },
     "private_headers": {
         "CFHandle.hpp": "platform/darwin/src/CFHandle.hpp"
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index a4f994a2f4..fa49a2f280 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -10,7 +10,6 @@
 #include <mbgl/map/mode.hpp>
 #include <mbgl/util/platform.hpp>
 #include <mbgl/storage/reachability.h>
-#include <mbgl/util/default_thread_pool.hpp>
 #include <mbgl/storage/resource_options.hpp>
 #include <mbgl/storage/network_status.hpp>
 #include <mbgl/style/style.hpp>
@@ -29,7 +28,6 @@
 #include <mbgl/util/default_styles.hpp>
 #include <mbgl/util/chrono.hpp>
 #include <mbgl/util/run_loop.hpp>
-#include <mbgl/util/shared_thread_pool.hpp>
 #include <mbgl/util/string.hpp>
 #include <mbgl/util/projection.hpp>
 
@@ -280,8 +278,6 @@ public:
     MBGLView *_mbglView;
     std::unique_ptr<MGLRenderFrontend> _rendererFrontend;
     
-    std::shared_ptr<mbgl::ThreadPool> _mbglThreadPool;
-
     BOOL _opaque;
 
     MGLAnnotationTagContextMap _annotationContextsByAnnotationTag;
@@ -476,9 +472,8 @@ public:
 
     // setup mbgl map
     MGLRendererConfiguration *config = [MGLRendererConfiguration currentConfiguration];
-    _mbglThreadPool = mbgl::sharedThreadPool();
 
-    auto renderer = std::make_unique<mbgl::Renderer>(*_mbglView, config.scaleFactor, *_mbglThreadPool, config.cacheDir, config.localFontFamilyName);
+    auto renderer = std::make_unique<mbgl::Renderer>(*_mbglView, config.scaleFactor, config.cacheDir, config.localFontFamilyName);
     BOOL enableCrossSourceCollisions = !config.perSourceCollisions;
     _rendererFrontend = std::make_unique<MGLRenderFrontend>(std::move(renderer), self, *_mbglView);
 
@@ -495,7 +490,7 @@ public:
                    .withAssetPath([NSBundle mainBundle].resourceURL.path.UTF8String);
 
     NSAssert(!_mbglMap, @"_mbglMap should be NULL");
-    _mbglMap = new mbgl::Map(*_rendererFrontend, *_mbglView, *_mbglThreadPool, mapOptions, resourceOptions);
+    _mbglMap = new mbgl::Map(*_rendererFrontend, *_mbglView, mapOptions, resourceOptions);
 
     // start paused if in IB
     if (background) {
@@ -772,7 +767,6 @@ public:
     _mbglView = nullptr;
 
     _rendererFrontend.reset();
-    _mbglThreadPool.reset();
 }
 
 - (void)dealloc
diff --git a/platform/linux/config.cmake b/platform/linux/config.cmake
index 4405e0583f..118dfe696c 100644
--- a/platform/linux/config.cmake
+++ b/platform/linux/config.cmake
@@ -72,11 +72,6 @@ macro(mbgl_platform_core)
         # Snapshotting
         PRIVATE platform/default/src/mbgl/map/map_snapshotter.cpp
         PRIVATE platform/default/include/mbgl/map/map_snapshotter.hpp
-
-        # Thread pool
-        PRIVATE platform/default/src/mbgl/util/default_thread_pool.cpp
-        PRIVATE platform/default/src/mbgl/util/default_thread_pool.cpp
-        PRIVATE platform/default/src/mbgl/util/shared_thread_pool.cpp
     )
 
     target_include_directories(mbgl-core
diff --git a/platform/macos/core-files.json b/platform/macos/core-files.json
index 9ec41f651a..abeda5796b 100644
--- a/platform/macos/core-files.json
+++ b/platform/macos/core-files.json
@@ -13,9 +13,7 @@
         "platform/default/src/mbgl/gl/headless_frontend.cpp",
         "platform/default/src/mbgl/map/map_snapshotter.cpp",
         "platform/default/src/mbgl/text/bidi.cpp",
-        "platform/default/src/mbgl/util/default_thread_pool.cpp",
         "platform/default/src/mbgl/util/png_writer.cpp",
-        "platform/default/src/mbgl/util/shared_thread_pool.cpp",
         "platform/default/src/mbgl/util/thread_local.cpp",
         "platform/default/src/mbgl/util/utf.cpp"
     ],
@@ -24,9 +22,7 @@
         "mbgl/util/image+MGLAdditions.hpp": "platform/darwin/include/mbgl/util/image+MGLAdditions.hpp",
         "mbgl/gl/headless_backend.hpp": "platform/default/include/mbgl/gl/headless_backend.hpp",
         "mbgl/gl/headless_frontend.hpp": "platform/default/include/mbgl/gl/headless_frontend.hpp",
-        "mbgl/map/map_snapshotter.hpp": "platform/default/include/mbgl/map/map_snapshotter.hpp",
-        "mbgl/util/default_thread_pool.hpp": "platform/default/include/mbgl/util/default_thread_pool.hpp",
-        "mbgl/util/shared_thread_pool.hpp": "platform/default/include/mbgl/util/shared_thread_pool.hpp"
+        "mbgl/map/map_snapshotter.hpp": "platform/default/include/mbgl/map/map_snapshotter.hpp"
     },
     "private_headers": {
         "CFHandle.hpp": "platform/darwin/src/CFHandle.hpp"
diff --git a/platform/macos/src/MGLMapView.mm b/platform/macos/src/MGLMapView.mm
index e9259cf907..77eb300aef 100644
--- a/platform/macos/src/MGLMapView.mm
+++ b/platform/macos/src/MGLMapView.mm
@@ -31,7 +31,6 @@
 #import <mbgl/annotation/annotation.hpp>
 #import <mbgl/map/camera.hpp>
 #import <mbgl/storage/reachability.h>
-#import <mbgl/util/default_thread_pool.hpp>
 #import <mbgl/style/image.hpp>
 #import <mbgl/renderer/renderer.hpp>
 #import <mbgl/gl/renderer_backend.hpp>
@@ -43,7 +42,6 @@
 #import <mbgl/util/chrono.hpp>
 #import <mbgl/util/exception.hpp>
 #import <mbgl/util/run_loop.hpp>
-#import <mbgl/util/shared_thread_pool.hpp>
 #import <mbgl/util/string.hpp>
 #import <mbgl/util/projection.hpp>
 
@@ -164,7 +162,6 @@ public:
     mbgl::Map *_mbglMap;
     MGLMapViewImpl *_mbglView;
     std::unique_ptr<MGLRenderFrontend> _rendererFrontend;
-    std::shared_ptr<mbgl::ThreadPool> _mbglThreadPool;
 
     NSPanGestureRecognizer *_panGestureRecognizer;
     NSMagnificationGestureRecognizer *_magnificationGestureRecognizer;
@@ -283,10 +280,9 @@ public:
     NSURL *legacyCacheURL = [cachesDirectoryURL URLByAppendingPathComponent:@"cache.db"];
     [[NSFileManager defaultManager] removeItemAtURL:legacyCacheURL error:NULL];
 
-    _mbglThreadPool = mbgl::sharedThreadPool();
     MGLRendererConfiguration *config = [MGLRendererConfiguration currentConfiguration];
 
-    auto renderer = std::make_unique<mbgl::Renderer>(*_mbglView, config.scaleFactor, *_mbglThreadPool, config.cacheDir, config.localFontFamilyName);
+    auto renderer = std::make_unique<mbgl::Renderer>(*_mbglView, config.scaleFactor, config.cacheDir, config.localFontFamilyName);
     BOOL enableCrossSourceCollisions = !config.perSourceCollisions;
     _rendererFrontend = std::make_unique<MGLRenderFrontend>(std::move(renderer), self, *_mbglView, true);
 
@@ -302,7 +298,7 @@ public:
     resourceOptions.withCachePath([[MGLOfflineStorage sharedOfflineStorage] mbglCachePath])
                    .withAssetPath([NSBundle mainBundle].resourceURL.path.UTF8String);
 
-    _mbglMap = new mbgl::Map(*_rendererFrontend, *_mbglView, *_mbglThreadPool, mapOptions, resourceOptions);
+    _mbglMap = new mbgl::Map(*_rendererFrontend, *_mbglView, mapOptions, resourceOptions);
 
     // Install the OpenGL layer. Interface Builder’s synchronous drawing means
     // we can’t display a map, so don’t even bother to have a map layer.
diff --git a/platform/node/src/node_map.cpp b/platform/node/src/node_map.cpp
index 7156a1f1bf..0a7da3a83a 100644
--- a/platform/node/src/node_map.cpp
+++ b/platform/node/src/node_map.cpp
@@ -630,8 +630,8 @@ void NodeMap::cancel() {
         reinterpret_cast<NodeMap *>(h->data)->renderFinished();
     });
 
-    frontend = std::make_unique<mbgl::HeadlessFrontend>(mbgl::Size{ 256, 256 }, pixelRatio, threadpool);
-    map = std::make_unique<mbgl::Map>(*frontend, mapObserver, threadpool,
+    frontend = std::make_unique<mbgl::HeadlessFrontend>(mbgl::Size{ 256, 256 }, pixelRatio);
+    map = std::make_unique<mbgl::Map>(*frontend, mapObserver,
                                       mbgl::MapOptions().withSize(frontend->getSize())
                                       .withPixelRatio(pixelRatio)
                                       .withMapMode(mode)
@@ -1214,8 +1214,8 @@ NodeMap::NodeMap(v8::Local<v8::Object> options)
             : true;
     }())
     , mapObserver(NodeMapObserver())
-    , frontend(std::make_unique<mbgl::HeadlessFrontend>(mbgl::Size { 256, 256 }, pixelRatio, threadpool))
-    , map(std::make_unique<mbgl::Map>(*frontend, mapObserver, threadpool,
+    , frontend(std::make_unique<mbgl::HeadlessFrontend>(mbgl::Size { 256, 256 }, pixelRatio))
+    , map(std::make_unique<mbgl::Map>(*frontend, mapObserver,
                                       mbgl::MapOptions().withSize(frontend->getSize())
                                       .withPixelRatio(pixelRatio)
                                       .withMapMode(mode)
diff --git a/platform/node/src/node_map.hpp b/platform/node/src/node_map.hpp
index 65664b34bb..d45dbec92b 100644
--- a/platform/node/src/node_map.hpp
+++ b/platform/node/src/node_map.hpp
@@ -1,7 +1,5 @@
 #pragma once
 
-#include "node_thread_pool.hpp"
-
 #include <mbgl/map/map.hpp>
 #include <mbgl/storage/file_source.hpp>
 #include <mbgl/util/image.hpp>
@@ -79,7 +77,6 @@ public:
     const float pixelRatio;
     mbgl::MapMode mode;
     bool crossSourceCollisions;
-    NodeThreadPool threadpool;
     NodeMapObserver mapObserver;
     std::unique_ptr<mbgl::HeadlessFrontend> frontend;
     std::unique_ptr<mbgl::Map> map;
diff --git a/platform/node/src/node_thread_pool.cpp b/platform/node/src/node_thread_pool.cpp
index 1f37565e8a..de403c605c 100644
--- a/platform/node/src/node_thread_pool.cpp
+++ b/platform/node/src/node_thread_pool.cpp
@@ -2,6 +2,7 @@
 #include "util/async_queue.hpp"
 
 #include <mbgl/actor/mailbox.hpp>
+#include <mbgl/platform/background_scheduler.hpp>
 
 namespace node_mbgl {
 
@@ -35,3 +36,14 @@ void NodeThreadPool::Worker::WorkComplete() {
 }
 
 } // namespace node_mbgl
+
+namespace mbgl {
+namespace platform {
+
+Scheduler& GetBackgroundScheduler() {
+    static node_mbgl::NodeThreadPool pool;
+    return pool;
+}
+
+} // namespace platform
+} // namespace mbgl
diff --git a/platform/qt/qt.cmake b/platform/qt/qt.cmake
index 911af25bc4..fb572b807b 100644
--- a/platform/qt/qt.cmake
+++ b/platform/qt/qt.cmake
@@ -17,12 +17,6 @@ set(MBGL_QT_CORE_FILES
     PRIVATE platform/default/include/mbgl/gl/headless_backend.hpp
     PRIVATE platform/qt/src/headless_backend_qt.cpp
 
-    # Thread pool
-    PRIVATE platform/default/src/mbgl/util/shared_thread_pool.cpp
-    PRIVATE platform/default/include/mbgl/util/shared_thread_pool.hpp
-    PRIVATE platform/default/src/mbgl/util/default_thread_pool.cpp
-    PRIVATE platform/default/include/mbgl/util/default_thread_pool.hpp
-
     # Thread
     PRIVATE platform/qt/src/thread_local.cpp
 
diff --git a/platform/qt/src/qmapboxgl.cpp b/platform/qt/src/qmapboxgl.cpp
index e54733aba7..329bf23085 100644
--- a/platform/qt/src/qmapboxgl.cpp
+++ b/platform/qt/src/qmapboxgl.cpp
@@ -43,7 +43,6 @@
 #include <mbgl/util/projection.hpp>
 #include <mbgl/util/rapidjson.hpp>
 #include <mbgl/util/run_loop.hpp>
-#include <mbgl/util/shared_thread_pool.hpp>
 #include <mbgl/util/traits.hpp>
 #include <mbgl/actor/scheduler.hpp>
 
@@ -1724,7 +1723,6 @@ mbgl::ResourceOptions resourceOptionsFromQMapboxGLSettings(const QMapboxGLSettin
 
 QMapboxGLPrivate::QMapboxGLPrivate(QMapboxGL *q, const QMapboxGLSettings &settings, const QSize &size, qreal pixelRatio_)
     : QObject(q)
-    , m_threadPool(mbgl::sharedThreadPool())
     , m_mode(settings.contextMode())
     , m_pixelRatio(pixelRatio_)
     , m_localFontFamily(settings.localFontFamily())
@@ -1741,7 +1739,7 @@ QMapboxGLPrivate::QMapboxGLPrivate(QMapboxGL *q, const QMapboxGLSettings &settin
     auto resourceOptions = resourceOptionsFromQMapboxGLSettings(settings);
 
     // Setup the Map object.
-    mapObj = std::make_unique<mbgl::Map>(*this, *m_mapObserver, *m_threadPool,
+    mapObj = std::make_unique<mbgl::Map>(*this, *m_mapObserver,
                                          mapOptionsFromQMapboxGLSettings(settings, size, m_pixelRatio),
                                          resourceOptions);
 
@@ -1799,7 +1797,6 @@ void QMapboxGLPrivate::createRenderer()
 
     m_mapRenderer = std::make_unique<QMapboxGLMapRenderer>(
         m_pixelRatio,
-        *m_threadPool,
         m_mode,
         m_localFontFamily
     );
diff --git a/platform/qt/src/qmapboxgl_map_renderer.cpp b/platform/qt/src/qmapboxgl_map_renderer.cpp
index d72b5d0f2c..eba50af6bf 100644
--- a/platform/qt/src/qmapboxgl_map_renderer.cpp
+++ b/platform/qt/src/qmapboxgl_map_renderer.cpp
@@ -26,9 +26,9 @@ static auto *getScheduler() {
     return scheduler.localData().get();
 };
 
-QMapboxGLMapRenderer::QMapboxGLMapRenderer(qreal pixelRatio, mbgl::ThreadPool &tp, QMapboxGLSettings::GLContextMode mode, const QString &localFontFamily)
+QMapboxGLMapRenderer::QMapboxGLMapRenderer(qreal pixelRatio, QMapboxGLSettings::GLContextMode mode, const QString &localFontFamily)
     : m_backend(static_cast<mbgl::gfx::ContextMode>(mode)),
-      m_renderer(std::make_unique<mbgl::Renderer>(m_backend, pixelRatio, tp, mbgl::optional<std::string> {},
+      m_renderer(std::make_unique<mbgl::Renderer>(m_backend, pixelRatio, mbgl::optional<std::string> {},
                  localFontFamily.isEmpty() ? mbgl::nullopt : mbgl::optional<std::string> { localFontFamily.toStdString() }))
     , m_forceScheduler(needsToForceScheduler())
 {
diff --git a/platform/qt/src/qmapboxgl_map_renderer.hpp b/platform/qt/src/qmapboxgl_map_renderer.hpp
index 7db0da99fa..2769b2b874 100644
--- a/platform/qt/src/qmapboxgl_map_renderer.hpp
+++ b/platform/qt/src/qmapboxgl_map_renderer.hpp
@@ -5,7 +5,6 @@
 
 #include <mbgl/renderer/renderer.hpp>
 #include <mbgl/renderer/renderer_observer.hpp>
-#include <mbgl/util/shared_thread_pool.hpp>
 #include <mbgl/util/util.hpp>
 
 #include <QtGlobal>
@@ -25,7 +24,7 @@ class QMapboxGLMapRenderer : public QObject
     Q_OBJECT
 
 public:
-    QMapboxGLMapRenderer(qreal pixelRatio, mbgl::ThreadPool &, QMapboxGLSettings::GLContextMode, const QString &localFontFamily);
+    QMapboxGLMapRenderer(qreal pixelRatio, QMapboxGLSettings::GLContextMode, const QString &localFontFamily);
     virtual ~QMapboxGLMapRenderer();
 
     void render();
diff --git a/platform/qt/src/qmapboxgl_p.hpp b/platform/qt/src/qmapboxgl_p.hpp
index 6a5b5ce04f..7f7040d7ac 100644
--- a/platform/qt/src/qmapboxgl_p.hpp
+++ b/platform/qt/src/qmapboxgl_p.hpp
@@ -8,7 +8,6 @@
 #include <mbgl/map/map.hpp>
 #include <mbgl/renderer/renderer_frontend.hpp>
 #include <mbgl/storage/resource_transform.hpp>
-#include <mbgl/util/default_thread_pool.hpp>
 #include <mbgl/util/geo.hpp>
 
 #include <QObject>
@@ -56,7 +55,6 @@ private:
     std::shared_ptr<mbgl::UpdateParameters> m_updateParameters;
 
     std::unique_ptr<QMapboxGLMapObserver> m_mapObserver;
-    std::shared_ptr<mbgl::ThreadPool> m_threadPool;
     std::unique_ptr<QMapboxGLMapRenderer> m_mapRenderer;
     std::unique_ptr<mbgl::Actor<mbgl::ResourceTransform>> m_resourceTransform;
 
diff --git a/platform/qt/src/qmapboxgl_renderer_backend.hpp b/platform/qt/src/qmapboxgl_renderer_backend.hpp
index aba8003323..f821eda969 100644
--- a/platform/qt/src/qmapboxgl_renderer_backend.hpp
+++ b/platform/qt/src/qmapboxgl_renderer_backend.hpp
@@ -4,7 +4,6 @@
 
 #include <mbgl/gfx/renderable.hpp>
 #include <mbgl/gl/renderer_backend.hpp>
-#include <mbgl/util/shared_thread_pool.hpp>
 
 class QMapboxGLRendererBackend final : public mbgl::gl::RendererBackend,
                                        public mbgl::gfx::Renderable {