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Add external memory accounting to JsRpcStub deserialization #6233

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Merged
ketanhwr merged 2 commits into from
Mar 18, 2026
Merged

Add external memory accounting to JsRpcStub deserialization #6233

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4ad05c5
Add external memory accounting to JsRpcStub deserialization
ketanhwr Mar 4, 2026
f31d336
Remove vestigial JsRpcStub constructor
ketanhwr Mar 18, 2026
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19 changes: 17 additions & 2 deletions src/workerd/api/worker-rpc.c++
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Original file line number Diff line number Diff line change
Expand Up @@ -738,6 +738,15 @@ JsRpcStub::JsRpcStub(
disposalGroup.list.add(*this);
}

JsRpcStub::JsRpcStub(IoOwn<rpc::JsRpcTarget::Client> capnpClient,
RpcStubDisposalGroup& disposalGroup,
jsg::ExternalMemoryAdjustment externalMemoryAdjustment)
: capnpClient(kj::mv(capnpClient)),
disposalGroup(disposalGroup),
externalMemoryAdjustment(kj::mv(externalMemoryAdjustment)) {
disposalGroup.list.add(*this);
}

JsRpcStub::~JsRpcStub() noexcept(false) {
KJ_IF_SOME(d, disposalGroup) {
d.list.remove(*this);
Expand Down Expand Up @@ -834,6 +843,7 @@ jsg::Ref<JsRpcStub> JsRpcStub::dup(jsg::Lock& js) {

void JsRpcStub::dispose() {
capnpClient = kj::none;
externalMemoryAdjustment = kj::none;
KJ_IF_SOME(d, disposalGroup) {
d.list.remove(*this);
disposalGroup = kj::none;
Expand Down Expand Up @@ -916,8 +926,13 @@ jsg::Ref<JsRpcStub> JsRpcStub::deserialize(
KJ_REQUIRE(reader.isRpcTarget(), "external table slot type doesn't match serialization tag");

auto& ioctx = IoContext::current();
return js.alloc<JsRpcStub>(
ioctx.addObject(kj::heap(reader.getRpcTarget())), externalHandler->getDisposalGroup());

// Account for membrane/promise memory in the KJ heap (~1600 bytes per stub from profiling).
static constexpr size_t ESTIMATED_EXTERNAL_MEMORY_PER_STUB = 1600;
auto externalMemory = js.getExternalMemoryAdjustment(ESTIMATED_EXTERNAL_MEMORY_PER_STUB);

return js.alloc<JsRpcStub>(ioctx.addObject(kj::heap(reader.getRpcTarget())),
externalHandler->getDisposalGroup(), kj::mv(externalMemory));
}

static bool isFunctionForRpc(jsg::Lock& js, v8::Local<v8::Function> func) {
Expand Down
4 changes: 4 additions & 0 deletions src/workerd/api/worker-rpc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -372,6 +372,9 @@ class JsRpcStub: public JsRpcClientProvider {
public:
JsRpcStub(IoOwn<rpc::JsRpcTarget::Client> capnpClient): capnpClient(kj::mv(capnpClient)) {}
JsRpcStub(IoOwn<rpc::JsRpcTarget::Client> capnpClient, RpcStubDisposalGroup& disposalGroup);
JsRpcStub(IoOwn<rpc::JsRpcTarget::Client> capnpClient,
RpcStubDisposalGroup& disposalGroup,
jsg::ExternalMemoryAdjustment externalMemoryAdjustment);
~JsRpcStub() noexcept(false);

rpc::JsRpcTarget::Client getClient();
Expand Down Expand Up @@ -414,6 +417,7 @@ class JsRpcStub: public JsRpcClientProvider {

kj::Maybe<RpcStubDisposalGroup&> disposalGroup;
kj::ListLink<JsRpcStub> disposalGroupLink;
kj::Maybe<jsg::ExternalMemoryAdjustment> externalMemoryAdjustment;

friend class RpcStubDisposalGroup;
};
Expand Down