Fix crash in postMessage that repro'd after ~100,000 messages

6 files changed, 57 insertions, 21 deletions

diff --git a/src/bun.js/bindings/ScriptExecutionContext.cpp b/src/bun.js/bindings/ScriptExecutionContext.cpp
index f878fd9fb..d93478ed8 100644
--- a/src/bun.js/bindings/ScriptExecutionContext.cpp
+++ b/src/bun.js/bindings/ScriptExecutionContext.cpp
@@ -120,8 +120,7 @@ void ScriptExecutionContext::regenerateIdentifier()
 
     m_identifier = ++lastUniqueIdentifier;
 
-    Locker locker { allScriptExecutionContextsMapLock };
-    allScriptExecutionContextsMap().add(m_identifier, this);
+    addToContextsMap();
 }
 
 void ScriptExecutionContext::addToContextsMap()
diff --git a/src/bun.js/bindings/webcore/JSWorker.cpp b/src/bun.js/bindings/webcore/JSWorker.cpp
index 68e06a2a0..bcf670d63 100644
--- a/src/bun.js/bindings/webcore/JSWorker.cpp
+++ b/src/bun.js/bindings/webcore/JSWorker.cpp
@@ -162,8 +162,16 @@ template<> EncodedJSValue JSC_HOST_CALL_ATTRIBUTES JSWorkerDOMConstructor::const
     auto jsValue = toJSNewlyCreated<IDLInterface<Worker>>(*lexicalGlobalObject, *castedThis->globalObject(), throwScope, WTFMove(object));
     if constexpr (IsExceptionOr<decltype(object)>)
         RETURN_IF_EXCEPTION(throwScope, {});
+
+    auto& impl = jsCast<JSWorker*>(jsValue)->wrapped();
+    if (!impl.updatePtr()) {
+        throwVMError(lexicalGlobalObject, throwScope, "Failed to start Worker thread"_s);
+        return encodedJSValue();
+    }
+
     setSubclassStructureIfNeeded<Worker>(lexicalGlobalObject, callFrame, asObject(jsValue));
     RETURN_IF_EXCEPTION(throwScope, {});
+
     return JSValue::encode(jsValue);
 }
 JSC_ANNOTATE_HOST_FUNCTION(JSWorkerDOMConstructorConstruct, JSWorkerDOMConstructor::construct);
diff --git a/src/bun.js/bindings/webcore/Worker.cpp b/src/bun.js/bindings/webcore/Worker.cpp
index d92b6e2e5..dfbc0e007 100644
--- a/src/bun.js/bindings/webcore/Worker.cpp
+++ b/src/bun.js/bindings/webcore/Worker.cpp
@@ -105,7 +105,7 @@ Worker::Worker(ScriptExecutionContext& context, WorkerOptions&& options)
     auto addResult = allWorkers().add(m_clientIdentifier, this);
     ASSERT_UNUSED(addResult, addResult.isNewEntry);
 }
-
+extern "C" bool WebWorker__updatePtr(void* worker, Worker* ptr);
 extern "C" void* WebWorker__create(
     Worker* worker,
     void* parent,
@@ -125,6 +125,18 @@ void Worker::setKeepAlive(bool keepAlive)
     WebWorker__setRef(impl_, keepAlive);
 }
 
+bool Worker::updatePtr()
+{
+    if (!WebWorker__updatePtr(impl_, this)) {
+        m_wasTerminated = true;
+        m_isClosing = true;
+        m_isOnline = false;
+        return false;
+    }
+
+    return true;
+}
+
 ExceptionOr<Ref<Worker>> Worker::create(ScriptExecutionContext& context, const String& urlInit, WorkerOptions&& options)
 {
     auto worker = adoptRef(*new Worker(context, WTFMove(options)));
diff --git a/src/bun.js/bindings/webcore/Worker.h b/src/bun.js/bindings/webcore/Worker.h
index 99a54e37f..b0b8e0a2b 100644
--- a/src/bun.js/bindings/webcore/Worker.h
+++ b/src/bun.js/bindings/webcore/Worker.h
@@ -70,6 +70,7 @@ public:
     void terminate();
     bool wasTerminated() const { return m_wasTerminated; }
     bool hasPendingActivity() const;
+    bool updatePtr();
 
     String identifier() const { return m_identifier; }
     const String& name() const { return m_options.name; }
diff --git a/src/bun.js/module_loader.zig b/src/bun.js/module_loader.zig
index 483ff94cb..6a04540b1 100644
--- a/src/bun.js/module_loader.zig
+++ b/src/bun.js/module_loader.zig
@@ -1697,6 +1697,12 @@ pub const ModuleLoader = struct {
                 // so it consistently handles bundled imports
                 // we can't take the shortcut of just directly importing the file, sadly.
                 .@"bun:main" => {
+                    defer {
+                        if (jsc_vm.worker) |worker| {
+                            worker.queueInitialTask();
+                        }
+                    }
+
                     if (comptime disable_transpilying) {
                         return ResolvedSource{
                             .allocator = null,
diff --git a/src/bun.js/web_worker.zig b/src/bun.js/web_worker.zig
index df2e63c3a..39ab2c8f1 100644
--- a/src/bun.js/web_worker.zig
+++ b/src/bun.js/web_worker.zig
@@ -19,20 +19,39 @@ pub const WebWorker = struct {
     store_fd: bool = false,
     arena: bun.MimallocArena = undefined,
     name: [:0]const u8 = "Worker",
-    cpp_worker: *void,
+    cpp_worker: *anyopaque,
     allowed_to_exit: bool = false,
     mini: bool = false,
     parent_poll_ref: JSC.PollRef = .{},
     initial_poll_ref: JSC.PollRef = .{},
+    did_send_initial_task: bool = false,
 
-    extern fn WebWorker__dispatchExit(?*JSC.JSGlobalObject, *void, i32) void;
-    extern fn WebWorker__dispatchOnline(this: *void, *JSC.JSGlobalObject) void;
-    extern fn WebWorker__dispatchError(*JSC.JSGlobalObject, *void, bun.String, JSValue) void;
+    extern fn WebWorker__dispatchExit(?*JSC.JSGlobalObject, *anyopaque, i32) void;
+    extern fn WebWorker__dispatchOnline(this: *anyopaque, *JSC.JSGlobalObject) void;
+    extern fn WebWorker__dispatchError(*JSC.JSGlobalObject, *anyopaque, bun.String, JSValue) void;
     export fn WebWorker__getParentWorker(vm: *JSC.VirtualMachine) ?*anyopaque {
         var worker = vm.worker orelse return null;
         return worker.cpp_worker;
     }
 
+    export fn WebWorker__updatePtr(worker: *WebWorker, ptr: *anyopaque) bool {
+        worker.cpp_worker = ptr;
+
+        var thread = std.Thread.spawn(
+            .{ .stack_size = 2 * 1024 * 1024 },
+            startWithErrorHandling,
+            .{worker},
+        ) catch {
+            worker.deinit();
+            worker.parent_poll_ref.unref(worker.parent);
+            worker.initial_poll_ref.unref(worker.parent);
+            bun.default_allocator.destroy(worker);
+            return false;
+        };
+        thread.detach();
+        return true;
+    }
+
     pub fn hasPendingActivity(this: *WebWorker) callconv(.C) bool {
         JSC.markBinding(@src());
 
@@ -105,23 +124,13 @@ pub const WebWorker = struct {
             worker.parent_poll_ref.ref(parent);
         }
 
-        var thread = std.Thread.spawn(
-            .{ .stack_size = 2 * 1024 * 1024 },
-            startWithErrorHandling,
-            .{worker},
-        ) catch {
-            worker.deinit();
-            worker.requested_terminate = true;
-            worker.parent_poll_ref.unref(worker.parent);
-            worker.initial_poll_ref.unref(worker.parent);
-            return null;
-        };
-        thread.detach();
-
         return worker;
     }
 
-    fn queueInitialTask(this: *WebWorker) void {
+    pub fn queueInitialTask(this: *WebWorker) void {
+        if (this.did_send_initial_task) return;
+        this.did_send_initial_task = true;
+
         const Unref = struct {
             pub fn unref(worker: *WebWorker) void {
                 worker.initial_poll_ref.unref(worker.parent);
@@ -364,6 +373,7 @@ pub const WebWorker = struct {
             @export(create, .{ .name = "WebWorker__create" });
             @export(terminate, .{ .name = "WebWorker__terminate" });
             @export(setRef, .{ .name = "WebWorker__setRef" });
+            _ = WebWorker__updatePtr;
         }
     }