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Commit 5f57005

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bripkenscjihrig
bripkens
authored and
cjihrig
committed
v8,src: expose statistics about heap spaces
Provide means to inspect information about the separate heap spaces via a callable API. This is helpful to analyze memory issues. Fixes: #2079 PR-URL: #4463 Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: James M Snell <jasnell@gmail.com>
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‎doc/api/v8.markdown‎

Copy file name to clipboardExpand all lines: doc/api/v8.markdown
+49Lines changed: 49 additions & 0 deletions
  • Display the source diff
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Original file line numberDiff line numberDiff line change
@@ -21,6 +21,55 @@ Returns an object with the following properties
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}
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```
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## getHeapSpaceStatistics()
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Returns statistics about the V8 heap spaces, i.e. the segments which make up
27+
the V8 heap. Order of heap spaces nor availability of a heap space can be
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guaranteed as the statistics are provided via the V8 `GetHeapSpaceStatistics`
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function.
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Example result:
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```
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[
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{
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"space_name": "new_space",
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"space_size": 2063872,
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"space_used_size": 951112,
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"space_available_size": 80824,
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"physical_space_size": 2063872
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},
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{
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"space_name": "old_space",
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"space_size": 3090560,
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"space_used_size": 2493792,
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"space_available_size": 0,
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"physical_space_size": 3090560
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},
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{
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"space_name": "code_space",
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"space_size": 1260160,
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"space_used_size": 644256,
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"space_available_size": 960,
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"physical_space_size": 1260160
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},
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{
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"space_name": "map_space",
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"space_size": 1094160,
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"space_used_size": 201608,
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"space_available_size": 0,
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"physical_space_size": 1094160
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},
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{
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"space_name": "large_object_space",
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"space_size": 0,
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"space_used_size": 0,
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"space_available_size": 1490980608,
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"physical_space_size": 0
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}
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]
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```
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2473
## setFlagsFromString(string)
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Set additional V8 command line flags. Use with care; changing settings
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‎lib/v8.js‎

Copy file name to clipboardExpand all lines: lib/v8.js
+32-1Lines changed: 32 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,16 +16,28 @@
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const v8binding = process.binding('v8');
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// Properties for heap statistics buffer extraction.
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const heapStatisticsBuffer =
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new Uint32Array(v8binding.heapStatisticsArrayBuffer);
21-
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const kTotalHeapSizeIndex = v8binding.kTotalHeapSizeIndex;
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const kTotalHeapSizeExecutableIndex = v8binding.kTotalHeapSizeExecutableIndex;
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const kTotalPhysicalSizeIndex = v8binding.kTotalPhysicalSizeIndex;
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const kTotalAvailableSize = v8binding.kTotalAvailableSize;
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const kUsedHeapSizeIndex = v8binding.kUsedHeapSizeIndex;
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const kHeapSizeLimitIndex = v8binding.kHeapSizeLimitIndex;
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// Properties for heap space statistics buffer extraction.
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const heapSpaceStatisticsBuffer =
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new Uint32Array(v8binding.heapSpaceStatisticsArrayBuffer);
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const kHeapSpaces = v8binding.kHeapSpaces;
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const kNumberOfHeapSpaces = kHeapSpaces.length;
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const kHeapSpaceStatisticsPropertiesCount =
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v8binding.kHeapSpaceStatisticsPropertiesCount;
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const kSpaceSizeIndex = v8binding.kSpaceSizeIndex;
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const kSpaceUsedSizeIndex = v8binding.kSpaceUsedSizeIndex;
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const kSpaceAvailableSizeIndex = v8binding.kSpaceAvailableSizeIndex;
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const kPhysicalSpaceSizeIndex = v8binding.kPhysicalSpaceSizeIndex;
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exports.getHeapStatistics = function() {
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const buffer = heapStatisticsBuffer;
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@@ -42,3 +54,22 @@ exports.getHeapStatistics = function() {
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};
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exports.setFlagsFromString = v8binding.setFlagsFromString;
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exports.getHeapSpaceStatistics = function() {
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const heapSpaceStatistics = new Array(kNumberOfHeapSpaces);
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const buffer = heapSpaceStatisticsBuffer;
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v8binding.updateHeapSpaceStatisticsArrayBuffer();
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for (let i = 0; i < kNumberOfHeapSpaces; i++) {
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const propertyOffset = i * kHeapSpaceStatisticsPropertiesCount;
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heapSpaceStatistics[i] = {
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space_name: kHeapSpaces[i],
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space_size: buffer[propertyOffset + kSpaceSizeIndex],
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space_used_size: buffer[propertyOffset + kSpaceUsedSizeIndex],
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space_available_size: buffer[propertyOffset + kSpaceAvailableSizeIndex],
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physical_space_size: buffer[propertyOffset + kPhysicalSpaceSizeIndex]
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};
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}
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return heapSpaceStatistics;
75+
};
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‎src/env-inl.h‎

Copy file name to clipboardExpand all lines: src/env-inl.h
+12Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -242,6 +242,7 @@ inline Environment::~Environment() {
242242
isolate_data()->Put();
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delete[] heap_statistics_buffer_;
245+
delete[] heap_space_statistics_buffer_;
245246
delete[] http_parser_buffer_;
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}
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@@ -374,6 +375,17 @@ inline void Environment::set_heap_statistics_buffer(uint32_t* pointer) {
374375
heap_statistics_buffer_ = pointer;
375376
}
376377

378+
inline uint32_t* Environment::heap_space_statistics_buffer() const {
379+
CHECK_NE(heap_space_statistics_buffer_, nullptr);
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return heap_space_statistics_buffer_;
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}
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inline void Environment::set_heap_space_statistics_buffer(uint32_t* pointer) {
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CHECK_EQ(heap_space_statistics_buffer_, nullptr); // Should be set only once.
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heap_space_statistics_buffer_ = pointer;
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}
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377389
inline char* Environment::http_parser_buffer() const {
378390
return http_parser_buffer_;
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}
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‎src/env.h‎

Copy file name to clipboardExpand all lines: src/env.h
+4Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -462,6 +462,9 @@ class Environment {
462462
inline uint32_t* heap_statistics_buffer() const;
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inline void set_heap_statistics_buffer(uint32_t* pointer);
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inline uint32_t* heap_space_statistics_buffer() const;
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inline void set_heap_space_statistics_buffer(uint32_t* pointer);
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465468
inline char* http_parser_buffer() const;
466469
inline void set_http_parser_buffer(char* buffer);
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@@ -562,6 +565,7 @@ class Environment {
562565
int handle_cleanup_waiting_;
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uint32_t* heap_statistics_buffer_ = nullptr;
568+
uint32_t* heap_space_statistics_buffer_ = nullptr;
565569

566570
char* http_parser_buffer_;
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‎src/node_v8.cc‎

Copy file name to clipboardExpand all lines: src/node_v8.cc
+86-1Lines changed: 86 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,13 +7,16 @@
77

88
namespace node {
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using v8::Array;
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using v8::ArrayBuffer;
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using v8::Context;
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using v8::Function;
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using v8::FunctionCallbackInfo;
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using v8::HeapSpaceStatistics;
1416
using v8::HeapStatistics;
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using v8::Isolate;
1618
using v8::Local;
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using v8::NewStringType;
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using v8::Object;
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using v8::String;
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using v8::Uint32;
@@ -34,6 +37,21 @@ static const size_t kHeapStatisticsPropertiesCount =
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HEAP_STATISTICS_PROPERTIES(V);
3538
#undef V
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#define HEAP_SPACE_STATISTICS_PROPERTIES(V) \
41+
V(0, space_size, kSpaceSizeIndex) \
42+
V(1, space_used_size, kSpaceUsedSizeIndex) \
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V(2, space_available_size, kSpaceAvailableSizeIndex) \
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V(3, physical_space_size, kPhysicalSpaceSizeIndex)
45+
46+
#define V(a, b, c) +1
47+
static const size_t kHeapSpaceStatisticsPropertiesCount =
48+
HEAP_SPACE_STATISTICS_PROPERTIES(V);
49+
#undef V
50+
51+
// Will be populated in InitializeV8Bindings.
52+
static size_t number_of_heap_spaces = 0;
53+
54+
3755
void UpdateHeapStatisticsArrayBuffer(const FunctionCallbackInfo<Value>& args) {
3856
Environment* env = Environment::GetCurrent(args);
3957
HeapStatistics s;
@@ -45,6 +63,23 @@ void UpdateHeapStatisticsArrayBuffer(const FunctionCallbackInfo<Value>& args) {
4563
}
4664

4765

66+
void UpdateHeapSpaceStatisticsBuffer(const FunctionCallbackInfo<Value>& args) {
67+
Environment* env = Environment::GetCurrent(args);
68+
HeapSpaceStatistics s;
69+
Isolate* const isolate = env->isolate();
70+
uint32_t* buffer = env->heap_space_statistics_buffer();
71+
72+
for (size_t i = 0; i < number_of_heap_spaces; i++) {
73+
isolate->GetHeapSpaceStatistics(&s, i);
74+
size_t const property_offset = i * kHeapSpaceStatisticsPropertiesCount;
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#define V(index, name, _) buffer[property_offset + index] = \
76+
static_cast<uint32_t>(s.name());
77+
HEAP_SPACE_STATISTICS_PROPERTIES(V)
78+
#undef V
79+
}
80+
}
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82+
4883
void SetFlagsFromString(const FunctionCallbackInfo<Value>& args) {
4984
Environment* env = Environment::GetCurrent(args);
5085

@@ -62,10 +97,10 @@ void InitializeV8Bindings(Local<Object> target,
6297
Local<Value> unused,
6398
Local<Context> context) {
6499
Environment* env = Environment::GetCurrent(context);
100+
65101
env->SetMethod(target,
66102
"updateHeapStatisticsArrayBuffer",
67103
UpdateHeapStatisticsArrayBuffer);
68-
env->SetMethod(target, "setFlagsFromString", SetFlagsFromString);
69104

70105
env->set_heap_statistics_buffer(new uint32_t[kHeapStatisticsPropertiesCount]);
71106

@@ -84,6 +119,56 @@ void InitializeV8Bindings(Local<Object> target,
84119

85120
HEAP_STATISTICS_PROPERTIES(V)
86121
#undef V
122+
123+
target->Set(FIXED_ONE_BYTE_STRING(env->isolate(),
124+
"kHeapSpaceStatisticsPropertiesCount"),
125+
Uint32::NewFromUnsigned(env->isolate(),
126+
kHeapSpaceStatisticsPropertiesCount));
127+
128+
number_of_heap_spaces = env->isolate()->NumberOfHeapSpaces();
129+
130+
// Heap space names are extracted once and exposed to JavaScript to
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// avoid excessive creation of heap space name Strings.
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HeapSpaceStatistics s;
133+
const Local<Array> heap_spaces = Array::New(env->isolate(),
134+
number_of_heap_spaces);
135+
for (size_t i = 0; i < number_of_heap_spaces; i++) {
136+
env->isolate()->GetHeapSpaceStatistics(&s, i);
137+
Local<String> heap_space_name = String::NewFromUtf8(env->isolate(),
138+
s.space_name(),
139+
NewStringType::kNormal)
140+
.ToLocalChecked();
141+
heap_spaces->Set(i, heap_space_name);
142+
}
143+
target->Set(FIXED_ONE_BYTE_STRING(env->isolate(), "kHeapSpaces"),
144+
heap_spaces);
145+
146+
env->SetMethod(target,
147+
"updateHeapSpaceStatisticsArrayBuffer",
148+
UpdateHeapSpaceStatisticsBuffer);
149+
150+
env->set_heap_space_statistics_buffer(
151+
new uint32_t[kHeapSpaceStatisticsPropertiesCount * number_of_heap_spaces]);
152+
153+
const size_t heap_space_statistics_buffer_byte_length =
154+
sizeof(*env->heap_space_statistics_buffer()) *
155+
kHeapSpaceStatisticsPropertiesCount *
156+
number_of_heap_spaces;
157+
158+
target->Set(FIXED_ONE_BYTE_STRING(env->isolate(),
159+
"heapSpaceStatisticsArrayBuffer"),
160+
ArrayBuffer::New(env->isolate(),
161+
env->heap_space_statistics_buffer(),
162+
heap_space_statistics_buffer_byte_length));
163+
164+
#define V(i, _, name) \
165+
target->Set(FIXED_ONE_BYTE_STRING(env->isolate(), #name), \
166+
Uint32::NewFromUnsigned(env->isolate(), i));
167+
168+
HEAP_SPACE_STATISTICS_PROPERTIES(V)
169+
#undef V
170+
171+
env->SetMethod(target, "setFlagsFromString", SetFlagsFromString);
87172
}
88173

89174
} // namespace node
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‎test/parallel/test-v8-stats.js‎

Copy file name to clipboardExpand all lines: test/parallel/test-v8-stats.js
+19Lines changed: 19 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -15,3 +15,22 @@ assert.deepEqual(Object.keys(s).sort(), keys);
1515
keys.forEach(function(key) {
1616
assert.equal(typeof s[key], 'number');
1717
});
18+
19+
20+
const expectedHeapSpaces = [
21+
'new_space',
22+
'old_space',
23+
'code_space',
24+
'map_space',
25+
'large_object_space'
26+
];
27+
const heapSpaceStatistics = v8.getHeapSpaceStatistics();
28+
const actualHeapSpaceNames = heapSpaceStatistics.map(s => s.space_name);
29+
assert.deepEqual(actualHeapSpaceNames.sort(), expectedHeapSpaces.sort());
30+
heapSpaceStatistics.forEach(heapSpace => {
31+
assert.strictEqual(typeof heapSpace.space_name, 'string');
32+
assert.strictEqual(typeof heapSpace.space_size, 'number');
33+
assert.strictEqual(typeof heapSpace.space_used_size, 'number');
34+
assert.strictEqual(typeof heapSpace.space_available_size, 'number');
35+
assert.strictEqual(typeof heapSpace.physical_space_size, 'number');
36+
});

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