Faster Chrome profile import

flamechart.ts

@@ -69,5 +69,7 @@ export class Flamechart {
 
     this.totalWeight = source.getTotalWeight()
     source.forEachCall(openFrame, closeFrame)
+
+    if (!isFinite(this.minFrameWidth)) this.minFrameWidth = 1
   }
 }

import/chrome.ts

@@ -1,5 +1,5 @@
 import {Profile, TimeFormatter, FrameInfo} from '../profile'
-import {getOrInsert} from '../utils'
+import {getOrInsert, lastOf} from '../utils'
 
 interface TimelineEvent {
   pid: number,
@@ -50,6 +50,24 @@ export function importFromChromeTimeline(events: TimelineEvent[]) {
   return importFromChromeCPUProfile(chromeProfile)
 }
 
+
+const callFrameToFrameInfo = new Map<CPUProfileCallFrame, FrameInfo>()
+function frameInfoForCallFrame(callFrame: CPUProfileCallFrame) {
+  return getOrInsert(callFrameToFrameInfo, callFrame, (callFrame) => {
+    const name = callFrame.functionName || "(anonymous)"
+    const file = callFrame.url
+    const line = callFrame.lineNumber
+    const col = callFrame.columnNumber
+    return {
+      key: `${name}:${file}:${line}:${col}`,
+      name,
+      file,
+      line,
+      col
+    }
+  })
+}
+
 export function importFromChromeCPUProfile(chromeProfile: CPUProfile) {
   const profile = new Profile(chromeProfile.endTime - chromeProfile.startTime)
 
@@ -90,60 +108,56 @@ export function importFromChromeCPUProfile(chromeProfile: CPUProfile) {
     timeDeltas.push(elapsed)
   }
 
-  const callFrameToFrameInfo = new Map<CPUProfileCallFrame, FrameInfo>()
+  let prevStack: CPUProfileNode[] = []
 
-  let lastNonGCStackTop: CPUProfileNode | null = null
+  let value = 0
   for (let i = 0; i < samples.length; i++) {
     const timeDelta = timeDeltas[i+1] || 0
     const nodeId = samples[i]
-    let node = nodeById.get(nodeId)
-    if (!node) continue
+    let stackTop = nodeById.get(nodeId)
+    if (!stackTop) continue
 
-    const stack: FrameInfo[] = []
+    // Find lowest common ancestor of the current stack and the previous one
+    let lca: CPUProfileNode | null = null
 
-    if (node.callFrame.functionName === "(garbage collector)") {
+    // This is O(n^2), but n should be relatively small here (stack height),
+    // so hopefully this isn't much of a problem
+    for (
+      lca = stackTop;
+      lca && prevStack.indexOf(lca) === -1;
+      lca = lca.callFrame.functionName === "(garbage collector)" ? lastOf(prevStack) : lca.parent || null
+    ) {}
+
+    // Close frames that are no longer open
+    while (prevStack.length > 0 && lastOf(prevStack) != lca) {
+      const closingNode = prevStack.pop()!
+      const frame = frameInfoForCallFrame(closingNode.callFrame)
+      profile.leaveFrame(frame, value)
+    }
+
+    // Open frames that are now becoming open
+    const toOpen: CPUProfileNode[] = []
+    for (
+      let node: CPUProfileNode | null = stackTop;
+      node && node != lca;
       // Place GC calls on top of the previous call stack
-      const frame = getOrInsert(callFrameToFrameInfo, node.callFrame, (callFrame) => ({
-        key: callFrame.functionName,
-        name: callFrame.functionName,
-        file: callFrame.url,
-        line: callFrame.lineNumber,
-        col: callFrame.columnNumber
-      }))
-      stack.push(frame)
-      if (!lastNonGCStackTop) {
-        profile.appendSample(stack, timeDelta)
-        continue
-      } else {
-        node = lastNonGCStackTop
-      }
+      node = node.callFrame.functionName === "(garbage collector)" ? lastOf(prevStack) : node.parent || null
+    ) {
+      toOpen.push(node)
+    }
+    toOpen.reverse()
+
+    for (let node of toOpen) {
+      profile.enterFrame(frameInfoForCallFrame(node.callFrame), value)
     }
 
-    lastNonGCStackTop = node
+    prevStack = prevStack.concat(toOpen)
+    value += timeDelta
+  }
 
-    // TODO(jlfwong): This is silly and slow, but good enough for now
-    for (; node; node = node.parent) {
-      if (node.callFrame.functionName === '(root)') continue
-      if (node.callFrame.functionName === '(idle)') continue
-
-      const frame = getOrInsert(callFrameToFrameInfo, node.callFrame, (callFrame) => {
-        const name = callFrame.functionName || "(anonymous)"
-        const file = callFrame.url
-        const line = callFrame.lineNumber
-        const col = callFrame.columnNumber
-        return {
-          key: `${name}:${file}:${line}:${col}`,
-          name,
-          file,
-          line,
-          col
-        }
-      })
-      stack.push(frame)
-    }
-    stack.reverse()
-
-    profile.appendSample(stack, timeDelta)
+  // Close frames that are open at the end of the trace
+  for (let i = prevStack.length - 1; i >= 0; i--) {
+    profile.leaveFrame(frameInfoForCallFrame(prevStack[i].callFrame), value)
   }
 
   profile.setValueFormatter(new TimeFormatter('microseconds'))

profile.ts

@@ -288,16 +288,26 @@ export class Profile {
     let stack = useAppendOrder ? this.appendOrderStack : this.groupedOrderStack
     this.addWeightsToNodes(value, stack)
 
-    let node = lastOf(stack)
-    if (node) {
-      const last = useAppendOrder ? lastOf(node.children) : node.children.find(c => c.frame === frame)
+    let prevTop = lastOf(stack)
+
+    if (prevTop) {
+      if (useAppendOrder) {
+        const delta = value - this.lastValue!
+        if (delta > 0) {
+          this.samples.push(prevTop)
+          this.weights.push(value - this.lastValue!)
+        }
+      }
+
+      const last = useAppendOrder ? lastOf(prevTop.children) : prevTop.children.find(c => c.frame === frame)
+      let node: CallTreeNode
       if (last && last.frame == frame) {
         node = last
       } else {
-        const parent = node
-        node = new CallTreeNode(frame, node)
-        parent.children.push(node)
+        node = new CallTreeNode(frame, prevTop)
+        prevTop.children.push(node)
       }
+      stack.push(node)
     }
   }
   enterFrame(frameInfo: FrameInfo, value: number) {
@@ -317,7 +327,12 @@ export class Profile {
     this.addWeightsToNodes(value, stack)
 
     if (useAppendOrder) {
-      this.appendOrderStack.pop()
+      const leavingStackTop = this.appendOrderStack.pop()
+      const delta = value - this.lastValue!
+      if (delta > 0) {
+        this.samples.push(leavingStackTop!)
+        this.weights.push(value - this.lastValue!)
+      }
     } else {
       this.groupedOrderStack.pop()
     }
@@ -325,6 +340,7 @@ export class Profile {
   leaveFrame(frameInfo: FrameInfo, value: number) {
     const frame = getOrInsert(this.frames, frameInfo.key, () => new Frame(frameInfo))
     this.addWeightsToFrames(value)
+
     this._leaveFrame(frame, value, true)
     this._leaveFrame(frame, value, false)
 
@@ -334,7 +350,7 @@ export class Profile {
     if (frameCount === 1) {
       this.framesInStack.delete(frame)
     } else {
-      this.framesInStack.set(frame, frameCount)
+      this.framesInStack.set(frame, frameCount - 1)
     }
     this.lastValue = value
   }

sample/simple.cpuprofile

@@ -0,0 +1 @@
+{"nodes":[{"id":1,"callFrame":{"functionName":"(root)","scriptId":"0","url":"","lineNumber":-1,"columnNumber":-1},"hitCount":0,"children":[2]},{"id":2,"callFrame":{"functionName":"","scriptId":"164","url":"","lineNumber":0,"columnNumber":0},"hitCount":0,"children":[3]},{"id":3,"callFrame":{"functionName":"a","scriptId":"164","url":"","lineNumber":0,"columnNumber":10},"hitCount":0,"children":[4,6]},{"id":4,"callFrame":{"functionName":"b","scriptId":"164","url":"","lineNumber":5,"columnNumber":10},"hitCount":0,"children":[5]},{"id":5,"callFrame":{"functionName":"d","scriptId":"164","url":"","lineNumber":13,"columnNumber":10},"hitCount":14,"positionTicks":[{"line":16,"ticks":13},{"line":14,"ticks":1}],"children":[]},{"id":6,"callFrame":{"functionName":"c","scriptId":"164","url":"","lineNumber":9,"columnNumber":10},"hitCount":0,"children":[7]},{"id":7,"callFrame":{"functionName":"d","scriptId":"164","url":"","lineNumber":13,"columnNumber":10},"hitCount":14,"positionTicks":[{"line":16,"ticks":14}],"children":[]}],"startTime":163140599286,"endTime":163140647178,"samples":[2,5,5,5,5,5,5,5,5,5,5,5,5,5,5,7,7,7,7,7,7,7,7,7,7,7,7,7,7],"timeDeltas":[11575,1060,1045,1270,1271,1187,1274,1270,1020,1249,1258,1272,1266,1075,1271,1274,1268,1266,1289,1286,1272,1136,1276,1274,1265,1265,1271,1272,1143]}

sample/simple.js

@@ -0,0 +1,24 @@
+function a() {
+  b();
+  c();
+}
+
+function b() {
+  d();
+}
+
+function c() {
+  d();
+}
+
+function d() {
+  let prod = 1;
+  for (let i = 1; i < 10000000; i++) {
+    prod *= i
+  }
+  return prod;
+}
+
+console.profile('a')
+a();
+console.profileEnd('a')