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async_hooks: improve resource stack performance
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Removes some of the performance overhead that came with
`executionAsyncResource()` by using the JS resource array
only as a cache for the values provided by C++. The fact that we now
use an entry trampoline is used to pass the resource without
requiring extra C++/JS boundary crossings, and the direct accesses
to the JS resource array from C++ are removed in all fast paths.

This particularly improves performance when async hooks are not
being used.

This is a continuation of #33575
and shares some of its code with it.

    ./node benchmark/compare.js --new ./node --old ./node-master --runs 30 --filter messageport worker | Rscript benchmark/compare.R
    [00:06:14|% 100| 1/1 files | 60/60 runs | 2/2 configs]: Done
                                                       confidence improvement accuracy (*)    (**)   (***)
     worker/messageport.js n=1000000 payload='object'         **     12.64 %       ±7.30%  ±9.72% ±12.65%
     worker/messageport.js n=1000000 payload='string'          *     11.08 %       ±9.00% ±11.98% ±15.59%

    ./node benchmark/compare.js --new ./node --old ./node-master --runs 20 --filter async-resource-vs-destroy async_hooks | Rscript benchmark/compare.R
    [00:22:35|% 100| 1/1 files | 40/40 runs | 6/6 configs]: Done
                                                                                                                                                                         confidence improvement accuracy (*)
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='async' type='async-local-storage' benchmarker='autocannon'                     1.60 %       ±7.35%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='async' type='async-resource' benchmarker='autocannon'                          6.05 %       ±6.57%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='async' type='destroy' benchmarker='autocannon'                          *      8.27 %       ±7.50%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='callbacks' type='async-local-storage' benchmarker='autocannon'                 7.42 %       ±8.22%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='callbacks' type='async-resource' benchmarker='autocannon'                      4.33 %       ±7.84%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='callbacks' type='destroy' benchmarker='autocannon'                             5.96 %       ±7.15%
                                                                                                                                                                           (**)   (***)
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='async' type='async-local-storage' benchmarker='autocannon'      ±9.84% ±12.94%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='async' type='async-resource' benchmarker='autocannon'           ±8.81% ±11.60%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='async' type='destroy' benchmarker='autocannon'                 ±10.07% ±13.28%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='callbacks' type='async-local-storage' benchmarker='autocannon' ±11.01% ±14.48%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='callbacks' type='async-resource' benchmarker='autocannon'      ±10.50% ±13.81%
     async_hooks/async-resource-vs-destroy.js n=1000000 duration=5 connections=500 path='/' asyncMethod='callbacks' type='destroy' benchmarker='autocannon'              ±9.58% ±12.62%

Refs: #33575

PR-URL: #34319
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Gerhard Stöbich <[email protected]>
Reviewed-By: Stephen Belanger <[email protected]>
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@addaleax
addaleax committed Sep 22, 2020
1 parent b977672 commit b2241e9
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Showing 7 changed files with 129 additions and 44 deletions.
33 changes: 18 additions & 15 deletions lib/internal/async_hooks.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,9 @@ const {
// each hook's after() callback.
const {
pushAsyncContext: pushAsyncContext_,
popAsyncContext: popAsyncContext_
popAsyncContext: popAsyncContext_,
executionAsyncResource: executionAsyncResource_,
clearAsyncIdStack,
} = async_wrap;
// For performance reasons, only track Promises when a hook is enabled.
const { enablePromiseHook, disablePromiseHook } = async_wrap;
Expand Down Expand Up @@ -87,7 +89,8 @@ const { resource_symbol, owner_symbol } = internalBinding('symbols');
// for a given step, that step can bail out early.
const { kInit, kBefore, kAfter, kDestroy, kTotals, kPromiseResolve,
kCheck, kExecutionAsyncId, kAsyncIdCounter, kTriggerAsyncId,
kDefaultTriggerAsyncId, kStackLength } = async_wrap.constants;
kDefaultTriggerAsyncId, kStackLength, kUsesExecutionAsyncResource
} = async_wrap.constants;

// Used in AsyncHook and AsyncResource.
const async_id_symbol = Symbol('asyncId');
Expand All @@ -108,7 +111,10 @@ function useDomainTrampoline(fn) {
domain_cb = fn;
}

function callbackTrampoline(asyncId, cb, ...args) {
function callbackTrampoline(asyncId, resource, cb, ...args) {
const index = async_hook_fields[kStackLength] - 1;
execution_async_resources[index] = resource;

if (asyncId !== 0 && hasHooks(kBefore))
emitBeforeNative(asyncId);

Expand All @@ -123,6 +129,7 @@ function callbackTrampoline(asyncId, cb, ...args) {
if (asyncId !== 0 && hasHooks(kAfter))
emitAfterNative(asyncId);

execution_async_resources.pop();
return result;
}

Expand All @@ -131,9 +138,15 @@ setCallbackTrampoline(callbackTrampoline);
const topLevelResource = {};

function executionAsyncResource() {
// Indicate to the native layer that this function is likely to be used,
// in which case it will inform JS about the current async resource via
// the trampoline above.
async_hook_fields[kUsesExecutionAsyncResource] = 1;

const index = async_hook_fields[kStackLength] - 1;
if (index === -1) return topLevelResource;
const resource = execution_async_resources[index];
const resource = execution_async_resources[index] ||
executionAsyncResource_(index);
return lookupPublicResource(resource);
}

Expand Down Expand Up @@ -413,16 +426,6 @@ function emitDestroyScript(asyncId) {
}


// Keep in sync with Environment::AsyncHooks::clear_async_id_stack
// in src/env-inl.h.
function clearAsyncIdStack() {
async_id_fields[kExecutionAsyncId] = 0;
async_id_fields[kTriggerAsyncId] = 0;
async_hook_fields[kStackLength] = 0;
execution_async_resources.splice(0, execution_async_resources.length);
}


function hasAsyncIdStack() {
return hasHooks(kStackLength);
}
Expand All @@ -432,7 +435,7 @@ function hasAsyncIdStack() {
function pushAsyncContext(asyncId, triggerAsyncId, resource) {
const offset = async_hook_fields[kStackLength];
if (offset * 2 >= async_wrap.async_ids_stack.length)
return pushAsyncContext_(asyncId, triggerAsyncId, resource);
return pushAsyncContext_(asyncId, triggerAsyncId);
async_wrap.async_ids_stack[offset * 2] = async_id_fields[kExecutionAsyncId];
async_wrap.async_ids_stack[offset * 2 + 1] = async_id_fields[kTriggerAsyncId];
execution_async_resources[offset] = resource;
Expand Down
6 changes: 3 additions & 3 deletions lib/internal/process/execution.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -186,10 +186,10 @@ function createOnGlobalUncaughtException() {
do {
emitAfter(executionAsyncId());
} while (hasAsyncIdStack());
// Or completely empty the id stack.
} else {
clearAsyncIdStack();
}
// And completely empty the id stack, including anything that may be
// cached on the native side.
clearAsyncIdStack();

return true;
};
Expand Down
21 changes: 13 additions & 8 deletions src/api/callback.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -160,12 +160,16 @@ MaybeLocal<Value> InternalMakeCallback(Environment* env,

Local<Function> hook_cb = env->async_hooks_callback_trampoline();
int flags = InternalCallbackScope::kNoFlags;
int hook_count = 0;
bool use_async_hooks_trampoline = false;
AsyncHooks* async_hooks = env->async_hooks();
if (!hook_cb.IsEmpty()) {
// Use the callback trampoline if there are any before or after hooks, or
// we can expect some kind of usage of async_hooks.executionAsyncResource().
flags = InternalCallbackScope::kSkipAsyncHooks;
AsyncHooks* async_hooks = env->async_hooks();
hook_count = async_hooks->fields()[AsyncHooks::kBefore] +
async_hooks->fields()[AsyncHooks::kAfter];
use_async_hooks_trampoline =
async_hooks->fields()[AsyncHooks::kBefore] +
async_hooks->fields()[AsyncHooks::kAfter] +
async_hooks->fields()[AsyncHooks::kUsesExecutionAsyncResource] > 0;
}

InternalCallbackScope scope(env, resource, asyncContext, flags);
Expand All @@ -175,12 +179,13 @@ MaybeLocal<Value> InternalMakeCallback(Environment* env,

MaybeLocal<Value> ret;

if (hook_count != 0) {
MaybeStackBuffer<Local<Value>, 16> args(2 + argc);
if (use_async_hooks_trampoline) {
MaybeStackBuffer<Local<Value>, 16> args(3 + argc);
args[0] = v8::Number::New(env->isolate(), asyncContext.async_id);
args[1] = callback;
args[1] = resource;
args[2] = callback;
for (int i = 0; i < argc; i++) {
args[i + 2] = argv[i];
args[i + 3] = argv[i];
}
ret = hook_cb->Call(env->context(), recv, args.length(), &args[0]);
} else {
Expand Down
23 changes: 21 additions & 2 deletions src/async_wrap.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -419,7 +419,7 @@ void AsyncWrap::PushAsyncContext(const FunctionCallbackInfo<Value>& args) {
// then the checks in push_async_ids() and pop_async_id() will.
double async_id = args[0]->NumberValue(env->context()).FromJust();
double trigger_async_id = args[1]->NumberValue(env->context()).FromJust();
env->async_hooks()->push_async_context(async_id, trigger_async_id, args[2]);
env->async_hooks()->push_async_context(async_id, trigger_async_id, {});
}


Expand All @@ -430,6 +430,22 @@ void AsyncWrap::PopAsyncContext(const FunctionCallbackInfo<Value>& args) {
}


void AsyncWrap::ExecutionAsyncResource(
const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);
uint32_t index;
if (!args[0]->Uint32Value(env->context()).To(&index)) return;
args.GetReturnValue().Set(
env->async_hooks()->native_execution_async_resource(index));
}


void AsyncWrap::ClearAsyncIdStack(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);
env->async_hooks()->clear_async_id_stack();
}


void AsyncWrap::AsyncReset(const FunctionCallbackInfo<Value>& args) {
CHECK(args[0]->IsObject());

Expand Down Expand Up @@ -502,6 +518,8 @@ void AsyncWrap::Initialize(Local<Object> target,
env->SetMethod(target, "setCallbackTrampoline", SetCallbackTrampoline);
env->SetMethod(target, "pushAsyncContext", PushAsyncContext);
env->SetMethod(target, "popAsyncContext", PopAsyncContext);
env->SetMethod(target, "executionAsyncResource", ExecutionAsyncResource);
env->SetMethod(target, "clearAsyncIdStack", ClearAsyncIdStack);
env->SetMethod(target, "queueDestroyAsyncId", QueueDestroyAsyncId);
env->SetMethod(target, "enablePromiseHook", EnablePromiseHook);
env->SetMethod(target, "disablePromiseHook", DisablePromiseHook);
Expand Down Expand Up @@ -540,7 +558,7 @@ void AsyncWrap::Initialize(Local<Object> target,

FORCE_SET_TARGET_FIELD(target,
"execution_async_resources",
env->async_hooks()->execution_async_resources());
env->async_hooks()->js_execution_async_resources());

target->Set(context,
env->async_ids_stack_string(),
Expand All @@ -562,6 +580,7 @@ void AsyncWrap::Initialize(Local<Object> target,
SET_HOOKS_CONSTANT(kTriggerAsyncId);
SET_HOOKS_CONSTANT(kAsyncIdCounter);
SET_HOOKS_CONSTANT(kDefaultTriggerAsyncId);
SET_HOOKS_CONSTANT(kUsesExecutionAsyncResource);
SET_HOOKS_CONSTANT(kStackLength);
#undef SET_HOOKS_CONSTANT
FORCE_SET_TARGET_FIELD(target, "constants", constants);
Expand Down
4 changes: 4 additions & 0 deletions src/async_wrap.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,10 @@ class AsyncWrap : public BaseObject {
static void GetAsyncId(const v8::FunctionCallbackInfo<v8::Value>& args);
static void PushAsyncContext(const v8::FunctionCallbackInfo<v8::Value>& args);
static void PopAsyncContext(const v8::FunctionCallbackInfo<v8::Value>& args);
static void ExecutionAsyncResource(
const v8::FunctionCallbackInfo<v8::Value>& args);
static void ClearAsyncIdStack(
const v8::FunctionCallbackInfo<v8::Value>& args);
static void AsyncReset(const v8::FunctionCallbackInfo<v8::Value>& args);
static void GetProviderType(const v8::FunctionCallbackInfo<v8::Value>& args);
static void QueueDestroyAsyncId(
Expand Down
72 changes: 59 additions & 13 deletions src/env-inl.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -104,8 +104,17 @@ inline AliasedFloat64Array& AsyncHooks::async_ids_stack() {
return async_ids_stack_;
}

inline v8::Local<v8::Array> AsyncHooks::execution_async_resources() {
return PersistentToLocal::Strong(execution_async_resources_);
v8::Local<v8::Array> AsyncHooks::js_execution_async_resources() {
if (UNLIKELY(js_execution_async_resources_.IsEmpty())) {
js_execution_async_resources_.Reset(
env()->isolate(), v8::Array::New(env()->isolate()));
}
return PersistentToLocal::Strong(js_execution_async_resources_);
}

v8::Local<v8::Object> AsyncHooks::native_execution_async_resource(size_t i) {
if (i >= native_execution_async_resources_.size()) return {};
return PersistentToLocal::Strong(native_execution_async_resources_[i]);
}

inline v8::Local<v8::String> AsyncHooks::provider_string(int idx) {
Expand All @@ -123,9 +132,7 @@ inline Environment* AsyncHooks::env() {
// Remember to keep this code aligned with pushAsyncContext() in JS.
inline void AsyncHooks::push_async_context(double async_id,
double trigger_async_id,
v8::Local<v8::Value> resource) {
v8::HandleScope handle_scope(env()->isolate());

v8::Local<v8::Object> resource) {
// Since async_hooks is experimental, do only perform the check
// when async_hooks is enabled.
if (fields_[kCheck] > 0) {
Expand All @@ -142,8 +149,19 @@ inline void AsyncHooks::push_async_context(double async_id,
async_id_fields_[kExecutionAsyncId] = async_id;
async_id_fields_[kTriggerAsyncId] = trigger_async_id;

auto resources = execution_async_resources();
USE(resources->Set(env()->context(), offset, resource));
#ifdef DEBUG
for (uint32_t i = offset; i < native_execution_async_resources_.size(); i++)
CHECK(native_execution_async_resources_[i].IsEmpty());
#endif

// When this call comes from JS (as a way of increasing the stack size),
// `resource` will be empty, because JS caches these values anyway, and
// we should avoid creating strong global references that might keep
// these JS resource objects alive longer than necessary.
if (!resource.IsEmpty()) {
native_execution_async_resources_.resize(offset + 1);
native_execution_async_resources_[offset].Reset(env()->isolate(), resource);
}
}

// Remember to keep this code aligned with popAsyncContext() in JS.
Expand Down Expand Up @@ -176,17 +194,45 @@ inline bool AsyncHooks::pop_async_context(double async_id) {
async_id_fields_[kTriggerAsyncId] = async_ids_stack_[2 * offset + 1];
fields_[kStackLength] = offset;

auto resources = execution_async_resources();
USE(resources->Delete(env()->context(), offset));
if (LIKELY(offset < native_execution_async_resources_.size() &&
!native_execution_async_resources_[offset].IsEmpty())) {
#ifdef DEBUG
for (uint32_t i = offset + 1;
i < native_execution_async_resources_.size();
i++) {
CHECK(native_execution_async_resources_[i].IsEmpty());
}
#endif
native_execution_async_resources_.resize(offset);
if (native_execution_async_resources_.size() <
native_execution_async_resources_.capacity() / 2 &&
native_execution_async_resources_.size() > 16) {
native_execution_async_resources_.shrink_to_fit();
}
}

if (UNLIKELY(js_execution_async_resources()->Length() > offset)) {
v8::HandleScope handle_scope(env()->isolate());
USE(js_execution_async_resources()->Set(
env()->context(),
env()->length_string(),
v8::Integer::NewFromUnsigned(env()->isolate(), offset)));
}

return fields_[kStackLength] > 0;
}

// Keep in sync with clearAsyncIdStack in lib/internal/async_hooks.js.
inline void AsyncHooks::clear_async_id_stack() {
auto isolate = env()->isolate();
void AsyncHooks::clear_async_id_stack() {
v8::Isolate* isolate = env()->isolate();
v8::HandleScope handle_scope(isolate);
execution_async_resources_.Reset(isolate, v8::Array::New(isolate));
if (!js_execution_async_resources_.IsEmpty()) {
USE(PersistentToLocal::Strong(js_execution_async_resources_)->Set(
env()->context(),
env()->length_string(),
v8::Integer::NewFromUnsigned(isolate, 0)));
}
native_execution_async_resources_.clear();
native_execution_async_resources_.shrink_to_fit();

async_id_fields_[kExecutionAsyncId] = 0;
async_id_fields_[kTriggerAsyncId] = 0;
Expand Down
14 changes: 11 additions & 3 deletions src/env.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -275,6 +275,7 @@ constexpr size_t kFsStatsBufferLength =
V(issuercert_string, "issuerCertificate") \
V(kill_signal_string, "killSignal") \
V(kind_string, "kind") \
V(length_string, "length") \
V(library_string, "library") \
V(mac_string, "mac") \
V(max_buffer_string, "maxBuffer") \
Expand Down Expand Up @@ -642,6 +643,7 @@ class AsyncHooks : public MemoryRetainer {
kTotals,
kCheck,
kStackLength,
kUsesExecutionAsyncResource,
kFieldsCount,
};

Expand All @@ -656,15 +658,20 @@ class AsyncHooks : public MemoryRetainer {
inline AliasedUint32Array& fields();
inline AliasedFloat64Array& async_id_fields();
inline AliasedFloat64Array& async_ids_stack();
inline v8::Local<v8::Array> execution_async_resources();
inline v8::Local<v8::Array> js_execution_async_resources();
// Returns the native executionAsyncResource value at stack index `index`.
// Resources provided on the JS side are not stored on the native stack,
// in which case an empty `Local<>` is returned.
// The `js_execution_async_resources` array contains the value in that case.
inline v8::Local<v8::Object> native_execution_async_resource(size_t index);

inline v8::Local<v8::String> provider_string(int idx);

inline void no_force_checks();
inline Environment* env();

inline void push_async_context(double async_id, double trigger_async_id,
v8::Local<v8::Value> execution_async_resource_);
v8::Local<v8::Object> execution_async_resource_);
inline bool pop_async_context(double async_id);
inline void clear_async_id_stack(); // Used in fatal exceptions.

Expand Down Expand Up @@ -709,7 +716,8 @@ class AsyncHooks : public MemoryRetainer {

void grow_async_ids_stack();

v8::Global<v8::Array> execution_async_resources_;
v8::Global<v8::Array> js_execution_async_resources_;
std::vector<v8::Global<v8::Object>> native_execution_async_resources_;
};

class ImmediateInfo : public MemoryRetainer {
Expand Down

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