Fix scheduler race conditions and add comprehensive test suite (#9348)

tests/integration/fixtures/external_components/scheduler_heap_stress_component/__init__.py

@@ -0,0 +1,21 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.const import CONF_ID
+
+scheduler_heap_stress_component_ns = cg.esphome_ns.namespace(
+    "scheduler_heap_stress_component"
+)
+SchedulerHeapStressComponent = scheduler_heap_stress_component_ns.class_(
+    "SchedulerHeapStressComponent", cg.Component
+)
+
+CONFIG_SCHEMA = cv.Schema(
+    {
+        cv.GenerateID(): cv.declare_id(SchedulerHeapStressComponent),
+    }
+).extend(cv.COMPONENT_SCHEMA)
+
+
+async def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+    await cg.register_component(var, config)

tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.cpp

@@ -0,0 +1,104 @@
+#include "heap_scheduler_stress_component.h"
+#include "esphome/core/log.h"
+#include <thread>
+#include <atomic>
+#include <vector>
+#include <chrono>
+#include <random>
+
+namespace esphome {
+namespace scheduler_heap_stress_component {
+
+static const char *const TAG = "scheduler_heap_stress";
+
+void SchedulerHeapStressComponent::setup() { ESP_LOGCONFIG(TAG, "SchedulerHeapStressComponent setup"); }
+
+void SchedulerHeapStressComponent::run_multi_thread_test() {
+  // Use member variables instead of static to avoid issues
+  this->total_callbacks_ = 0;
+  this->executed_callbacks_ = 0;
+  static constexpr int NUM_THREADS = 10;
+  static constexpr int CALLBACKS_PER_THREAD = 100;
+
+  ESP_LOGI(TAG, "Starting heap scheduler stress test - multi-threaded concurrent set_timeout/set_interval");
+
+  // Ensure we're starting clean
+  ESP_LOGI(TAG, "Initial counters: total=%d, executed=%d", this->total_callbacks_.load(),
+           this->executed_callbacks_.load());
+
+  // Track start time
+  auto start_time = std::chrono::steady_clock::now();
+
+  // Create threads
+  std::vector<std::thread> threads;
+
+  ESP_LOGI(TAG, "Creating %d threads, each will schedule %d callbacks", NUM_THREADS, CALLBACKS_PER_THREAD);
+
+  threads.reserve(NUM_THREADS);
+  for (int i = 0; i < NUM_THREADS; i++) {
+    threads.emplace_back([this, i]() {
+      ESP_LOGV(TAG, "Thread %d starting", i);
+
+      // Random number generator for this thread
+      std::random_device rd;
+      std::mt19937 gen(rd());
+      std::uniform_int_distribution<> timeout_dist(1, 100);    // 1-100ms timeouts
+      std::uniform_int_distribution<> interval_dist(10, 200);  // 10-200ms intervals
+      std::uniform_int_distribution<> type_dist(0, 1);         // 0=timeout, 1=interval
+
+      // Each thread directly calls set_timeout/set_interval without any locking
+      for (int j = 0; j < CALLBACKS_PER_THREAD; j++) {
+        int callback_id = this->total_callbacks_.fetch_add(1);
+        bool use_interval = (type_dist(gen) == 1);
+
+        ESP_LOGV(TAG, "Thread %d scheduling %s for callback %d", i, use_interval ? "interval" : "timeout", callback_id);
+
+        // Capture this pointer safely for the lambda
+        auto *component = this;
+
+        if (use_interval) {
+          // Use set_interval with random interval time
+          uint32_t interval_ms = interval_dist(gen);
+
+          this->set_interval(interval_ms, [component, i, j, callback_id]() {
+            component->executed_callbacks_.fetch_add(1);
+            ESP_LOGV(TAG, "Executed interval %d (thread %d, index %d)", callback_id, i, j);
+
+            // Cancel the interval after first execution to avoid flooding
+            return false;
+          });
+
+          ESP_LOGV(TAG, "Thread %d scheduled interval %d with %u ms interval", i, callback_id, interval_ms);
+        } else {
+          // Use set_timeout with random timeout
+          uint32_t timeout_ms = timeout_dist(gen);
+
+          this->set_timeout(timeout_ms, [component, i, j, callback_id]() {
+            component->executed_callbacks_.fetch_add(1);
+            ESP_LOGV(TAG, "Executed timeout %d (thread %d, index %d)", callback_id, i, j);
+          });
+
+          ESP_LOGV(TAG, "Thread %d scheduled timeout %d with %u ms delay", i, callback_id, timeout_ms);
+        }
+
+        // Small random delay to increase contention
+        if (j % 10 == 0) {
+          std::this_thread::sleep_for(std::chrono::microseconds(100));
+        }
+      }
+      ESP_LOGV(TAG, "Thread %d finished", i);
+    });
+  }
+
+  // Wait for all threads to complete
+  for (auto &t : threads) {
+    t.join();
+  }
+
+  auto end_time = std::chrono::steady_clock::now();
+  auto thread_time = std::chrono::duration_cast<std::chrono::milliseconds>(end_time - start_time).count();
+  ESP_LOGI(TAG, "All threads finished in %lldms. Created %d callbacks", thread_time, this->total_callbacks_.load());
+}
+
+}  // namespace scheduler_heap_stress_component
+}  // namespace esphome

tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include <atomic>
+
+namespace esphome {
+namespace scheduler_heap_stress_component {
+
+class SchedulerHeapStressComponent : public Component {
+ public:
+  void setup() override;
+  float get_setup_priority() const override { return setup_priority::LATE; }
+
+  void run_multi_thread_test();
+
+ private:
+  std::atomic<int> total_callbacks_{0};
+  std::atomic<int> executed_callbacks_{0};
+};
+
+}  // namespace scheduler_heap_stress_component
+}  // namespace esphome