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perf_hooks: simplify perf_hooks
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Remove the `performance.getEntries()` and `performance.clear*()`
variants and eliminate the accumulation of the global timeline
entries. The design of this particular bit of the API is a memory
leak and performance footgun. The `PerformanceObserver` API is
a better approach to consuming the data in a more transient way.

PR-URL: #19563
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
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@jasnell
jasnell committed Apr 3, 2018
1 parent d54f651 commit 2ec6995
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Showing 9 changed files with 38 additions and 320 deletions.
106 changes: 8 additions & 98 deletions doc/api/perf_hooks.md
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Original file line number Diff line number Diff line change
Expand Up @@ -10,14 +10,18 @@ is to support collection of high resolution performance metrics.
This is the same Performance API as implemented in modern Web browsers.

```js
const { performance } = require('perf_hooks');
const { PerformanceObserver, performance } = require('perf_hooks');

const obs = new PerformanceObserver((items) => {
console.log(items.getEntries()[0].duration);
performance.clearMarks();
});
obs.observe({ entryTypes: ['measure'] });

performance.mark('A');
doSomeLongRunningProcess(() => {
performance.mark('B');
performance.measure('A to B', 'A', 'B');
const measure = performance.getEntriesByName('A to B')[0];
console.log(measure.duration);
// Prints the number of milliseconds between Mark 'A' and Mark 'B'
});
```

Expand All @@ -26,35 +30,6 @@ doSomeLongRunningProcess(() => {
added: v8.5.0
-->

The `Performance` provides access to performance metric data. A single
instance of this class is provided via the `performance` property.

### performance.clearEntries(name)
<!-- YAML
added: v9.5.0
-->

Remove all performance entry objects with `entryType` equal to `name` from the
Performance Timeline.

### performance.clearFunctions([name])
<!-- YAML
added: v8.5.0
-->

* `name` {string}

If `name` is not provided, removes all `PerformanceFunction` objects from the
Performance Timeline. If `name` is provided, removes entries with `name`.

### performance.clearGC()
<!-- YAML
added: v8.5.0
-->

Remove all performance entry objects with `entryType` equal to `gc` from the
Performance Timeline.

### performance.clearMarks([name])
<!-- YAML
added: v8.5.0
Expand All @@ -65,53 +40,6 @@ added: v8.5.0
If `name` is not provided, removes all `PerformanceMark` objects from the
Performance Timeline. If `name` is provided, removes only the named mark.

### performance.clearMeasures([name])
<!-- YAML
added: v8.5.0
-->

* `name` {string}

If `name` is not provided, removes all `PerformanceMeasure` objects from the
Performance Timeline. If `name` is provided, removes only objects whose
`performanceEntry.name` matches `name`.

### performance.getEntries()
<!-- YAML
added: v8.5.0
-->

* Returns: {Array}

Returns a list of all `PerformanceEntry` objects in chronological order
with respect to `performanceEntry.startTime`.

### performance.getEntriesByName(name[, type])
<!-- YAML
added: v8.5.0
-->

* `name` {string}
* `type` {string}
* Returns: {Array}

Returns a list of all `PerformanceEntry` objects in chronological order
with respect to `performanceEntry.startTime` whose `performanceEntry.name` is
equal to `name`, and optionally, whose `performanceEntry.entryType` is equal to
`type`.

### performance.getEntriesByType(type)
<!-- YAML
added: v8.5.0
-->

* `type` {string}
* Returns: {Array}

Returns a list of all `PerformanceEntry` objects in chronological order
with respect to `performanceEntry.startTime` whose `performanceEntry.entryType`
is equal to `type`.

### performance.mark([name])
<!-- YAML
added: v8.5.0
Expand All @@ -125,20 +53,6 @@ Creates a new `PerformanceMark` entry in the Performance Timeline. A
`performanceEntry.duration` is always `0`. Performance marks are used
to mark specific significant moments in the Performance Timeline.

### performance.maxEntries
<!-- YAML
added: v9.6.0
-->

Value: {number}

The maximum number of Performance Entry items that should be added to the
Performance Timeline. This limit is not strictly enforced, but a process
warning will be emitted if the number of entries in the timeline exceeds
this limit.

Defaults to 150.

### performance.measure(name, startMark, endMark)
<!-- YAML
added: v8.5.0
Expand Down Expand Up @@ -220,7 +134,6 @@ const wrapped = performance.timerify(someFunction);
const obs = new PerformanceObserver((list) => {
console.log(list.getEntries()[0].duration);
obs.disconnect();
performance.clearFunctions();
});
obs.observe({ entryTypes: ['function'] });

Expand Down Expand Up @@ -608,7 +521,6 @@ hook.enable();
const obs = new PerformanceObserver((list, observer) => {
console.log(list.getEntries()[0]);
performance.clearMarks();
performance.clearMeasures();
observer.disconnect();
});
obs.observe({ entryTypes: ['measure'], buffered: true });
Expand Down Expand Up @@ -642,8 +554,6 @@ const obs = new PerformanceObserver((list) => {
console.log(`require('${entry[0]}')`, entry.duration);
});
obs.disconnect();
// Free memory
performance.clearFunctions();
});
obs.observe({ entryTypes: ['function'], buffered: true });

Expand Down
101 changes: 7 additions & 94 deletions lib/perf_hooks.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
const {
PerformanceEntry,
mark: _mark,
clearMark: _clearMark,
measure: _measure,
milestones,
observerCounts,
Expand Down Expand Up @@ -50,17 +51,11 @@ const kBuffering = Symbol('buffering');
const kQueued = Symbol('queued');
const kTimerified = Symbol('timerified');
const kInsertEntry = Symbol('insert-entry');
const kIndexEntry = Symbol('index-entry');
const kClearEntry = Symbol('clear-entry');
const kGetEntries = Symbol('get-entries');
const kIndex = Symbol('index');
const kMarks = Symbol('marks');
const kCount = Symbol('count');
const kMaxCount = Symbol('max-count');
const kDefaultMaxCount = 150;

observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_MARK] = 1;
observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_MEASURE] = 1;
const observers = {};
const observerableTypes = [
'node',
Expand Down Expand Up @@ -286,17 +281,12 @@ class PerformanceObserverEntryList {
const item = { entry };
L.append(this[kEntries], item);
this[kCount]++;
this[kIndexEntry](item);
}

get length() {
return this[kCount];
}

[kIndexEntry](entry) {
// Default implementation does nothing
}

[kGetEntries](name, type) {
const ret = [];
const list = this[kEntries];
Expand Down Expand Up @@ -407,72 +397,11 @@ class PerformanceObserver extends AsyncResource {
}
}

class Performance extends PerformanceObserverEntryList {
class Performance {
constructor() {
super();
this[kIndex] = {
[kMarks]: new Set()
};
this[kMaxCount] = kDefaultMaxCount;
this[kInsertEntry](nodeTiming);
}

set maxEntries(val) {
if (typeof val !== 'number' || val >>> 0 !== val) {
const errors = lazyErrors();
throw new errors.ERR_INVALID_ARG_TYPE('val', 'number', val);
}
this[kMaxCount] = Math.max(1, val >>> 0);
}

get maxEntries() {
return this[kMaxCount];
}

[kIndexEntry](item) {
const index = this[kIndex];
const type = item.entry.entryType;
let items = index[type];
if (!items) {
items = index[type] = {};
L.init(items);
}
const entry = item.entry;
L.append(items, { entry, item });
const count = this[kCount];
if (count > this[kMaxCount]) {
const text = count === 1 ? 'is 1 entry' : `are ${count} entries`;
process.emitWarning('Possible perf_hooks memory leak detected. ' +
`There ${text} in the ` +
'Performance Timeline. Use the clear methods ' +
'to remove entries that are no longer needed or ' +
'set performance.maxEntries equal to a higher ' +
'value (currently the maxEntries is ' +
`${this[kMaxCount]}).`);
}
}

[kClearEntry](type, name) {
const index = this[kIndex];
const items = index[type];
if (!items) return;
let item = L.peek(items);
while (item && item !== items) {
const entry = item.entry;
const next = item._idlePrev;
if (name !== undefined) {
if (entry.name === `${name}`) {
L.remove(item); // remove from the index
L.remove(item.item); // remove from the master
this[kCount]--;
}
} else {
L.remove(item); // remove from the index
L.remove(item.item); // remove from the master
this[kCount]--;
}
item = next;
}
}

get nodeTiming() {
Expand Down Expand Up @@ -507,27 +436,13 @@ class Performance extends PerformanceObserverEntryList {

clearMarks(name) {
name = name !== undefined ? `${name}` : name;
this[kClearEntry]('mark', name);
if (name !== undefined)
if (name !== undefined) {
this[kIndex][kMarks].delete(name);
else
_clearMark(name);
} else {
this[kIndex][kMarks].clear();
}

clearMeasures(name) {
this[kClearEntry]('measure', name);
}

clearGC() {
this[kClearEntry]('gc');
}

clearFunctions(name) {
this[kClearEntry]('function', name);
}

clearEntries(name) {
this[kClearEntry](name);
_clearMark();
}
}

timerify(fn) {
Expand Down Expand Up @@ -563,7 +478,6 @@ class Performance extends PerformanceObserverEntryList {

[kInspect]() {
return {
maxEntries: this.maxEntries,
nodeTiming: this.nodeTiming,
timeOrigin: this.timeOrigin
};
Expand Down Expand Up @@ -595,7 +509,6 @@ function observersCallback(entry) {
if (type === NODE_PERFORMANCE_ENTRY_TYPE_HTTP2)
collectHttp2Stats(entry);

performance[kInsertEntry](entry);
const list = getObserversList(type);

let current = L.peek(list);
Expand Down
14 changes: 13 additions & 1 deletion src/node_perf.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -130,7 +130,7 @@ void PerformanceEntry::Notify(Environment* env,
object.As<Object>(),
env->performance_entry_callback(),
1, &object,
node::async_context{0, 0}).ToLocalChecked();
node::async_context{0, 0});
}
}

Expand All @@ -153,6 +153,17 @@ void Mark(const FunctionCallbackInfo<Value>& args) {
args.GetReturnValue().Set(obj);
}

void ClearMark(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);
auto marks = env->performance_marks();

if (args.Length() == 0) {
marks->clear();
} else {
Utf8Value name(env->isolate(), args[0]);
marks->erase(*name);
}
}

inline uint64_t GetPerformanceMark(Environment* env, std::string name) {
auto marks = env->performance_marks();
Expand Down Expand Up @@ -395,6 +406,7 @@ void Initialize(Local<Object> target,
target->Set(context, performanceEntryString, fn).FromJust();
env->set_performance_entry_template(fn);

env->SetMethod(target, "clearMark", ClearMark);
env->SetMethod(target, "mark", Mark);
env->SetMethod(target, "measure", Measure);
env->SetMethod(target, "markMilestone", MarkMilestone);
Expand Down
10 changes: 1 addition & 9 deletions test/parallel/test-http2-perf_hooks.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ if (!common.hasCrypto)
const assert = require('assert');
const h2 = require('http2');

const { PerformanceObserver, performance } = require('perf_hooks');
const { PerformanceObserver } = require('perf_hooks');

const obs = new PerformanceObserver(common.mustCall((items) => {
const entry = items.getEntries()[0];
Expand Down Expand Up @@ -46,7 +46,6 @@ const obs = new PerformanceObserver(common.mustCall((items) => {
default:
assert.fail('invalid entry name');
}
performance.clearEntries('http2');
}, 4));
obs.observe({ entryTypes: ['http2'] });

Expand Down Expand Up @@ -101,10 +100,3 @@ server.on('listening', common.mustCall(() => {
}));

}));

process.on('exit', () => {
const entries = performance.getEntries();
// There shouldn't be any http2 entries left over.
assert.strictEqual(entries.length, 1);
assert.strictEqual(entries[0], performance.nodeTiming);
});
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