worker: add stack size resource limit option

doc/api/worker_threads.md

@@ -172,6 +172,7 @@ added: v13.2.0
   * `maxYoungGenerationSizeMb` {number}
   * `maxOldGenerationSizeMb` {number}
   * `codeRangeSizeMb` {number}
+  * `stackSizeMb` {number}
 
 Provides the set of JS engine resource constraints inside this Worker thread.
 If the `resourceLimits` option was passed to the [`Worker`][] constructor,
@@ -574,6 +575,8 @@ changes:
       recently created objects.
     * `codeRangeSizeMb` {number} The size of a pre-allocated memory range
       used for generated code.
+    * `stackSizeMb` {number} The default maximum stack size for the thread.
+      Small values may lead to unusable Worker instances. **Default:** `4`.
 
 ### Event: `'error'`
 <!-- YAML
@@ -667,6 +670,7 @@ added: v13.2.0
   * `maxYoungGenerationSizeMb` {number}
   * `maxOldGenerationSizeMb` {number}
   * `codeRangeSizeMb` {number}
+  * `stackSizeMb` {number}
 
 Provides the set of JS engine resource constraints for this Worker thread.
 If the `resourceLimits` option was passed to the [`Worker`][] constructor,

lib/internal/worker.js

@@ -54,6 +54,7 @@ const {
   kMaxYoungGenerationSizeMb,
   kMaxOldGenerationSizeMb,
   kCodeRangeSizeMb,
+  kStackSizeMb,
   kTotalResourceLimitCount
 } = internalBinding('worker');
 
@@ -379,14 +380,17 @@ function parseResourceLimits(obj) {
     ret[kMaxYoungGenerationSizeMb] = obj.maxYoungGenerationSizeMb;
   if (typeof obj.codeRangeSizeMb === 'number')
     ret[kCodeRangeSizeMb] = obj.codeRangeSizeMb;
+  if (typeof obj.stackSizeMb === 'number')
+    ret[kStackSizeMb] = obj.stackSizeMb;
   return ret;
 }
 
 function makeResourceLimits(float64arr) {
   return {
     maxYoungGenerationSizeMb: float64arr[kMaxYoungGenerationSizeMb],
     maxOldGenerationSizeMb: float64arr[kMaxOldGenerationSizeMb],
-    codeRangeSizeMb: float64arr[kCodeRangeSizeMb]
+    codeRangeSizeMb: float64arr[kCodeRangeSizeMb],
+    stackSizeMb: float64arr[kStackSizeMb]
   };
 }
 

src/node_worker.cc

@@ -39,6 +39,8 @@ using v8::Value;
 namespace node {
 namespace worker {
 
+constexpr double kMB = 1024 * 1024;
+
 Worker::Worker(Environment* env,
                Local<Object> wrap,
                const std::string& url,
@@ -93,8 +95,6 @@ bool Worker::is_stopped() const {
 void Worker::UpdateResourceConstraints(ResourceConstraints* constraints) {
   constraints->set_stack_limit(reinterpret_cast<uint32_t*>(stack_base_));
 
-  constexpr double kMB = 1024 * 1024;
-
   if (resource_limits_[kMaxYoungGenerationSizeMb] > 0) {
     constraints->set_max_young_generation_size_in_bytes(
         resource_limits_[kMaxYoungGenerationSizeMb] * kMB);
@@ -131,9 +131,7 @@ class WorkerThreadData {
     if (ret != 0) {
       char err_buf[128];
       uv_err_name_r(ret, err_buf, sizeof(err_buf));
-      w->custom_error_ = "ERR_WORKER_INIT_FAILED";
-      w->custom_error_str_ = err_buf;
-      w->stopped_ = true;
+      w->Exit(1, "ERR_WORKER_INIT_FAILED", err_buf);
       return;
     }
     loop_init_failed_ = false;
@@ -148,9 +146,9 @@ class WorkerThreadData {
 
     Isolate* isolate = Isolate::Allocate();
     if (isolate == nullptr) {
-      w->custom_error_ = "ERR_WORKER_OUT_OF_MEMORY";
-      w->custom_error_str_ = "Failed to create new Isolate";
-      w->stopped_ = true;
+      // TODO(addaleax): This should be ERR_WORKER_INIT_FAILED,
+      // ERR_WORKER_OUT_OF_MEMORY is for reaching the per-Worker heap limit.
+      w->Exit(1, "ERR_WORKER_OUT_OF_MEMORY", "Failed to create new Isolate");
       return;
     }
 
@@ -233,9 +231,7 @@ class WorkerThreadData {
 size_t Worker::NearHeapLimit(void* data, size_t current_heap_limit,
                              size_t initial_heap_limit) {
   Worker* worker = static_cast<Worker*>(data);
-  worker->custom_error_ = "ERR_WORKER_OUT_OF_MEMORY";
-  worker->custom_error_str_ = "JS heap out of memory";
-  worker->Exit(1);
+  worker->Exit(1, "ERR_WORKER_OUT_OF_MEMORY", "JS heap out of memory");
   // Give the current GC some extra leeway to let it finish rather than
   // crash hard. We are not going to perform further allocations anyway.
   constexpr size_t kExtraHeapAllowance = 16 * 1024 * 1024;
@@ -292,8 +288,9 @@ void Worker::Run() {
         TryCatch try_catch(isolate_);
         context = NewContext(isolate_);
         if (context.IsEmpty()) {
-          custom_error_ = "ERR_WORKER_OUT_OF_MEMORY";
-          custom_error_str_ = "Failed to create new Context";
+          // TODO(addaleax): This should be ERR_WORKER_INIT_FAILED,
+          // ERR_WORKER_OUT_OF_MEMORY is for reaching the per-Worker heap limit.
+          Exit(1, "ERR_WORKER_OUT_OF_MEMORY", "Failed to create new Context");
           return;
         }
       }
@@ -592,9 +589,20 @@ void Worker::StartThread(const FunctionCallbackInfo<Value>& args) {
 
   w->stopped_ = false;
 
+  if (w->resource_limits_[kStackSizeMb] > 0) {
+    if (w->resource_limits_[kStackSizeMb] * kMB < kStackBufferSize) {
+      w->resource_limits_[kStackSizeMb] = kStackBufferSize / kMB;
+      w->stack_size_ = kStackBufferSize;
+    } else {
+      w->stack_size_ = w->resource_limits_[kStackSizeMb] * kMB;
+    }
+  } else {
+    w->resource_limits_[kStackSizeMb] = w->stack_size_ / kMB;
+  }
+
   uv_thread_options_t thread_options;
   thread_options.flags = UV_THREAD_HAS_STACK_SIZE;
-  thread_options.stack_size = kStackSize;
+  thread_options.stack_size = w->stack_size_;
   int ret = uv_thread_create_ex(&w->tid_, &thread_options, [](void* arg) {
     // XXX: This could become a std::unique_ptr, but that makes at least
     // gcc 6.3 detect undefined behaviour when there shouldn't be any.
@@ -604,7 +612,7 @@ void Worker::StartThread(const FunctionCallbackInfo<Value>& args) {
 
     // Leave a few kilobytes just to make sure we're within limits and have
     // some space to do work in C++ land.
-    w->stack_base_ = stack_top - (kStackSize - kStackBufferSize);
+    w->stack_base_ = stack_top - (w->stack_size_ - kStackBufferSize);
 
     w->Run();
 
@@ -682,9 +690,16 @@ Local<Float64Array> Worker::GetResourceLimits(Isolate* isolate) const {
   return Float64Array::New(ab, 0, kTotalResourceLimitCount);
 }
 
-void Worker::Exit(int code) {
+void Worker::Exit(int code, const char* error_code, const char* error_message) {
   Mutex::ScopedLock lock(mutex_);
-  Debug(this, "Worker %llu called Exit(%d)", thread_id_.id, code);
+  Debug(this, "Worker %llu called Exit(%d, %s, %s)",
+        thread_id_.id, code, error_code, error_message);
+
+  if (error_code != nullptr) {
+    custom_error_ = error_code;
+    custom_error_str_ = error_message;
+  }
+
   if (env_ != nullptr) {
     exit_code_ = code;
     Stop(env_);
@@ -830,6 +845,7 @@ void InitWorker(Local<Object> target,
   NODE_DEFINE_CONSTANT(target, kMaxYoungGenerationSizeMb);
   NODE_DEFINE_CONSTANT(target, kMaxOldGenerationSizeMb);
   NODE_DEFINE_CONSTANT(target, kCodeRangeSizeMb);
+  NODE_DEFINE_CONSTANT(target, kStackSizeMb);
   NODE_DEFINE_CONSTANT(target, kTotalResourceLimitCount);
 }
 

src/node_worker.h

@@ -16,6 +16,7 @@ enum ResourceLimits {
   kMaxYoungGenerationSizeMb,
   kMaxOldGenerationSizeMb,
   kCodeRangeSizeMb,
+  kStackSizeMb,
   kTotalResourceLimitCount
 };
 
@@ -34,8 +35,11 @@ class Worker : public AsyncWrap {
   void Run();
 
   // Forcibly exit the thread with a specified exit code. This may be called
-  // from any thread.
-  void Exit(int code);
+  // from any thread. `error_code` and `error_message` can be used to create
+  // a custom `'error'` event before emitting `'exit'`.
+  void Exit(int code,
+            const char* error_code = nullptr,
+            const char* error_message = nullptr);
 
   // Wait for the worker thread to stop (in a blocking manner).
   void JoinThread();
@@ -92,7 +96,7 @@ class Worker : public AsyncWrap {
   void UpdateResourceConstraints(v8::ResourceConstraints* constraints);
 
   // Full size of the thread's stack.
-  static constexpr size_t kStackSize = 4 * 1024 * 1024;
+  size_t stack_size_ = 4 * 1024 * 1024;
   // Stack buffer size that is not available to the JS engine.
   static constexpr size_t kStackBufferSize = 192 * 1024;
 

test/parallel/test-worker-resource-limits.js

@@ -12,6 +12,7 @@ const testResourceLimits = {
   maxOldGenerationSizeMb: 16,
   maxYoungGenerationSizeMb: 4,
   codeRangeSizeMb: 16,
+  stackSizeMb: 1,
 };
 
 // Do not use isMainThread so that this test itself can be run inside a Worker.

test/parallel/test-worker-stack-overflow-stack-size.js

@@ -8,7 +8,7 @@ const { Worker } = require('worker_threads');
 // Verify that Workers don't care about --stack-size, as they have their own
 // fixed and known stack sizes.
 
-async function runWorker() {
+async function runWorker(options = {}) {
   const empiricalStackDepth = new Uint32Array(new SharedArrayBuffer(4));
   const worker = new Worker(`
   const { workerData: { empiricalStackDepth } } = require('worker_threads');
@@ -18,26 +18,45 @@ async function runWorker() {
   }
   f();`, {
     eval: true,
-    workerData: { empiricalStackDepth }
+    workerData: { empiricalStackDepth },
+    ...options
   });
 
   const [ error ] = await once(worker, 'error');
 
-  common.expectsError({
-    constructor: RangeError,
-    message: 'Maximum call stack size exceeded'
-  })(error);
+  if (!options.skipErrorCheck) {
+    common.expectsError({
+      constructor: RangeError,
+      message: 'Maximum call stack size exceeded'
+    })(error);
+  }
 
   return empiricalStackDepth[0];
 }
 
 (async function() {
-  v8.setFlagsFromString('--stack-size=500');
-  const w1stack = await runWorker();
-  v8.setFlagsFromString('--stack-size=1000');
-  const w2stack = await runWorker();
-  // Make sure the two stack sizes are within 10 % of each other, i.e. not
-  // affected by the different `--stack-size` settings.
-  assert(Math.max(w1stack, w2stack) / Math.min(w1stack, w2stack) < 1.1,
-         `w1stack = ${w1stack}, w2stack ${w2stack} are too far apart`);
+  {
+    v8.setFlagsFromString('--stack-size=500');
+    const w1stack = await runWorker();
+    v8.setFlagsFromString('--stack-size=1000');
+    const w2stack = await runWorker();
+    // Make sure the two stack sizes are within 10 % of each other, i.e. not
+    // affected by the different `--stack-size` settings.
+    assert(Math.max(w1stack, w2stack) / Math.min(w1stack, w2stack) < 1.1,
+           `w1stack = ${w1stack}, w2stack = ${w2stack} are too far apart`);
+  }
+
+  {
+    const w1stack = await runWorker({ resourceLimits: { stackSizeMb: 0.5 } });
+    const w2stack = await runWorker({ resourceLimits: { stackSizeMb: 1.0 } });
+    // Make sure the two stack sizes are at least 40 % apart from each other,
+    // i.e. affected by the different `stackSizeMb` settings.
+    assert(w2stack > w1stack * 1.4,
+           `w1stack = ${w1stack}, w2stack = ${w2stack} are too close`);
+  }
+
+  // Test that various low stack sizes result in an 'error' event.
+  for (const stackSizeMb of [ 0.001, 0.01, 0.1, 0.2, 0.3, 0.5 ]) {
+    await runWorker({ resourceLimits: { stackSizeMb }, skipErrorCheck: true });
+  }
 })().then(common.mustCall());