perf_hooks: add warning when too many entries in the timeline

PR-URL: https://github.com/nodejs/node/pull/18087
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 45 insertions, 4 deletions

diff --git a/lib/perf_hooks.js b/lib/perf_hooks.js
index 15256a63c0..6fd6e4a6b7 100644
--- a/lib/perf_hooks.js
+++ b/lib/perf_hooks.js
@@ -53,6 +53,9 @@ 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;
@@ -250,10 +253,17 @@ const nodeTiming = new PerformanceNodeTiming();
 // Maintains a list of entries as a linked list stored in insertion order.
 class PerformanceObserverEntryList {
   constructor() {
-    Object.defineProperty(this, kEntries, {
-      writable: true,
-      enumerable: false,
-      value: {}
+    Object.defineProperties(this, {
+      [kEntries]: {
+        writable: true,
+        enumerable: false,
+        value: {}
+      },
+      [kCount]: {
+        writable: true,
+        enumerable: false,
+        value: 0
+      }
     });
     L.init(this[kEntries]);
   }
@@ -261,9 +271,14 @@ class PerformanceObserverEntryList {
   [kInsertEntry](entry) {
     const item = { entry };
     L.append(this[kEntries], item);
+    this[kCount]++;
     this[kIndexEntry](item);
   }
 
+  get length() {
+    return this[kCount];
+  }
+
   [kIndexEntry](entry) {
     // Default implementation does nothing
   }
@@ -384,9 +399,22 @@ class Performance extends PerformanceObserverEntryList {
     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.TypeError('ERR_INVALID_ARG_TYPE', 'val', 'number');
+    }
+    this[kMaxCount] = Math.max(1, val >>> 0);
+  }
+
+  get maxEntries() {
+    return this[kMaxCount];
+  }
+
   [kIndexEntry](item) {
     const index = this[kIndex];
     const type = item.entry.entryType;
@@ -397,6 +425,17 @@ class Performance extends PerformanceObserverEntryList {
     }
     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) {
@@ -411,10 +450,12 @@ class Performance extends PerformanceObserverEntryList {
         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;
     }