Fixes "promise will never complete" when exceeding memory.

cloudflare · Jan 30, 2025 · 198db4d · 198db4d
1 parent 8790957
commit 198db4d
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Showing 3 changed files with 32 additions and 7 deletions.
diff --git a/src/workerd/io/io-context.h b/src/workerd/io/io-context.h
@@ -1257,23 +1257,40 @@ kj::_::ReducePromises<RemoveIoOwn<T>> IoContext::awaitJs(jsg::Lock& js, jsg::Pro
   auto paf = kj::newPromiseAndFulfiller<RemoveIoOwn<T>>();
   struct RefcountedFulfiller: public Finalizeable, public kj::Refcounted {
     kj::Own<kj::PromiseFulfiller<RemoveIoOwn<T>>> fulfiller;
+    kj::Own<const workerd::Worker::Isolate> isolate;
     bool isDone = false;
 
-    RefcountedFulfiller(kj::Own<kj::PromiseFulfiller<RemoveIoOwn<T>>> fulfiller)
-        : fulfiller(kj::mv(fulfiller)) {}
+    RefcountedFulfiller(kj::Own<const workerd::Worker::Isolate> isolate,
+        kj::Own<kj::PromiseFulfiller<RemoveIoOwn<T>>> fulfiller)
+        : fulfiller(kj::mv(fulfiller)),
+          isolate(kj::mv(isolate)) {}
 
     ~RefcountedFulfiller() noexcept(false) {
       if (!isDone) {
-        // The JavaScript resolver was garbage collected, i.e. JavaScript will never resolve
-        // this promise.
-        fulfiller->reject(JSG_KJ_EXCEPTION(FAILED, Error, "Promise will never complete."));
+        auto hasExcessivelyExceededHeapLimit =
+            isolate->getLimitEnforcer().hasExcessivelyExceededHeapLimit();
+        if (hasExcessivelyExceededHeapLimit) {
+          fulfiller->reject(
+              JSG_KJ_EXCEPTION(OVERLOADED, Error, "jsg.Error: Worker has exceeded memory limit."));
+        } else {
+          // The JavaScript resolver was garbage collected, i.e. JavaScript will never resolve
+          // this promise.
+          fulfiller->reject(JSG_KJ_EXCEPTION(FAILED, Error, "Promise will never complete."));
+        }
       }
     }
 
    private:
     kj::Maybe<kj::StringPtr> finalize() override {
       if (!isDone) {
-        fulfiller->reject(JSG_KJ_EXCEPTION(FAILED, Error, "Promise will never complete."));
+        auto hasExcessivelyExceededHeapLimit =
+            isolate->getLimitEnforcer().hasExcessivelyExceededHeapLimit();
+        if (hasExcessivelyExceededHeapLimit) {
+          fulfiller->reject(
+              JSG_KJ_EXCEPTION(OVERLOADED, Error, "jsg.Error: Worker has exceeded memory limit."));
+        } else {
+          fulfiller->reject(JSG_KJ_EXCEPTION(FAILED, Error, "Promise will never complete."));
+        }
         isDone = true;
         return "A hanging Promise was canceled. This happens when the worker runtime is waiting "
                "for a Promise from JavaScript to resolve, but has detected that the Promise "
@@ -1284,7 +1301,9 @@ kj::_::ReducePromises<RemoveIoOwn<T>> IoContext::awaitJs(jsg::Lock& js, jsg::Pro
       }
     }
   };
-  auto fulfiller = kj::refcounted<RefcountedFulfiller>(kj::mv(paf.fulfiller));
+  auto& isolate = Worker::Isolate::from(js);
+  auto fulfiller =
+      kj::refcounted<RefcountedFulfiller>(kj::atomicAddRef(isolate), kj::mv(paf.fulfiller));
 
   auto errorHandler = [fulfiller = addObject(kj::addRef(*fulfiller))](
                           jsg::Lock& js, jsg::Value jsExceptionRef) mutable {

diff --git a/src/workerd/io/limit-enforcer.h b/src/workerd/io/limit-enforcer.h
@@ -83,6 +83,8 @@ class IsolateLimitEnforcer: public kj::Refcounted {
   virtual size_t getBlobSizeLimit() const {
     return 128 * 1024 * 1024;  // 128 MB
   }
+
+  virtual bool hasExcessivelyExceededHeapLimit() const = 0;
 };
 
 // Abstract interface that enforces resource limits on a IoContext.

diff --git a/src/workerd/server/server.c++ b/src/workerd/server/server.c++
@@ -3184,6 +3184,10 @@ kj::Own<Server::Service> Server::makeWorker(kj::StringPtr name,
       // No limit on the number of iterations in workerd
       return kj::none;
     }
+
+    bool hasExcessivelyExceededHeapLimit() const override {
+      return false;
+    }
   };
 
   auto jsgobserver = kj::atomicRefcounted<JsgIsolateObserver>();