newrelic · bizob2828 · Mar 10, 2026 · Mar 10, 2026 · bizob2828 · Mar 10, 2026
diff --git a/simple-express-app/csv-visualizer.js b/simple-express-app/csv-visualizer.js
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const fs = require('node:fs/promises')
+const path = require('path')
+const express = require('express')
+const app = express()
+const PORT = 3001
+const monitorDir = path.join(__dirname, 'monitor-data')
+
+app.use(express.static(path.join(__dirname, 'public')))
+
+// List all CSV files in the directory
+app.get('/csv-list', async (req, res) => {
+  const contents = await fs.readdir(monitorDir)
+  const files = contents.filter((file) => file.endsWith('.csv'))
+  res.json(files)
+})
+
+// Fetch CSV data for a given file
+app.get('/data', async (req, res) => {
+  const file = req.query.file
+  if (!file || !file.endsWith('.csv')) {
+    res.status(400).send('Invalid CSV file')
+    return
+  }
+
+  let csvPath
+  try {
+    csvPath = await fs.realpath(path.resolve(monitorDir, file))
+  } catch (err) {
+    res.status(404).send(`Failed to find file ${err.message}`)
+    return
+  }
+
+  const csv = await fs.readFile(csvPath, 'utf8')
+  const lines = csv.trim().split('\n')
+  const headers = lines.shift().split(',')
+  // formats the data into a collection:
+  // [
+  //  { timestamp, cpu_user_ms, cpu_system_ms, etc }
+  // ]
+  const data = lines.map((line) => {
+    const values = line.split(',')
+    const obj = {}
+    headers.forEach((h, i) => {
+      obj[h] = values[i]
+    })
+    return obj
+  })
+  res.json({ headers, data })
+})
+
+app.listen(PORT, () => {
+  // eslint-disable-next-line no-console
+  console.log(`CSV visualizer running at http://localhost:${PORT}`)
+})
diff --git a/simple-express-app/index.js b/simple-express-app/index.js
@@ -20,3 +20,8 @@ app.get('/sns', async (req, res) => {
 })
 
 app.listen(PORT, () => console.log(`Example app listening on port ${PORT}!`))
+
+process.on('SIGINT', () => {
+  console.log('ending app server')
+  process.exit(0)
+})
diff --git a/simple-express-app/package.json b/simple-express-app/package.json
@@ -5,7 +5,10 @@
   "main": "index.js",
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1",
-    "start": "node -r newrelic --env-file .env index.js"
+    "start": "node -r newrelic --env-file .env index.js",
+    "start:perf:no-agent": "node -r ./v8-monitor.js index.js",
+    "start:perf:agent-no-profiling": "node -r ./v8-monitor.js -r newrelic --env-file .env_no_prof index.js",
+    "start:perf:agent-profiling": "node -r ./v8-monitor.js -r newrelic --env-file .env index.js"
   },
   "author": "",
   "license": "ISC",
@@ -14,6 +17,6 @@
     "bluebird": "^3.7.2",
     "body-parser": "^1.20.2",
     "express": "^4.18.2",
-    "newrelic": "^12.5.0"
+    "newrelic": "^13.15.0"
   }
 }
diff --git a/simple-express-app/public/index.html b/simple-express-app/public/index.html
@@ -0,0 +1,101 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <title>V8 Monitor CSV Visualization</title>
+  <script src="https://cdn.jsdelivr.net/npm/chart.js"></script>
+  <style>
+    body { font-family: sans-serif; margin: 2em; }
+    #controls { margin-bottom: 1em; }
+    canvas { max-width: 100%; }
+  </style>
+</head>
+<body>
+  <h1>V8 Monitor CSV Visualization</h1>
+  <div id="controls">
+    <label for="csvSelect">CSV File:</label>
+    <select id="csvSelect"></select>
+  </div>
+  <div id="charts"></div>
+  <script>
+    async function fetchCsvList() {
+      const res = await fetch('/csv-list');
+      return await res.json();
+    }
+
+    async function fetchData(file) {
+      const res = await fetch(`/data?file=${encodeURIComponent(file)}`);
+      return await res.json();
+    }
+
+    function renderAllCharts(headers, data) {
+      const chartsDiv = document.getElementById('charts');
+      chartsDiv.innerHTML = '';
+      const timestamps = data.map(row => row.timestamp);
+      headers.forEach(metric => {
+        if (metric === 'timestamp') return;
+        const values = data.map(row => parseFloat(row[metric]));
+        const container = document.createElement('div');
+        container.style.marginBottom = '2em';
+        const label = document.createElement('h3');
+        label.textContent = metric;
+        container.appendChild(label);
+        const canvas = document.createElement('canvas');
+        canvas.height = 80;
+        container.appendChild(canvas);
+        chartsDiv.appendChild(container);
+        const ctx = canvas.getContext('2d');
+        // Use distinct colors for percent metrics
+        let color = 'blue';
+        let yLabel = metric;
+        if (metric.endsWith('Percent')) {
+          if (metric === 'heapUsedPercent') color = 'green';
+          if (metric === 'cpuUserPercent') color = 'orange';
+          if (metric === 'cpuSystemPercent') color = 'red';
+          yLabel = metric + ' (%)';
+        }
+        new Chart(ctx, {
+          type: 'line',
+          data: {
+            labels: timestamps,
+            datasets: [{
+              label: metric,
+              data: values,
+              borderColor: color,
+              fill: false,
+            }],
+          },
+          options: {
+            scales: {
+              x: { display: true, title: { display: true, text: 'Timestamp' } },
+              y: { display: true, title: { display: true, text: yLabel } },
+            },
+          },
+        });
+      });
+    }
+
+    async function main() {
+      const csvList = await fetchCsvList();
+      const csvSelect = document.getElementById('csvSelect');
+      csvList.forEach(file => {
+        const option = document.createElement('option');
+        option.value = file;
+        option.textContent = file;
+        csvSelect.appendChild(option);
+      });
+      async function loadAndRender(file) {
+        const { headers, data } = await fetchData(file);
+        renderAllCharts(headers, data);
+      }
+      csvSelect.addEventListener('change', () => {
+        loadAndRender(csvSelect.value);
+      });
+      if (csvList.length > 0) {
+        loadAndRender(csvList[0]);
+      }
+    }
+    main();
+  </script>
+</body>
+</html>
diff --git a/simple-express-app/run-profiling-test.sh b/simple-express-app/run-profiling-test.sh
@@ -0,0 +1,35 @@
+#!/bin/bash
+RUN_TIME=1
+commands=("start:perf:no-agent" "start:perf:agent-no-profiling" "start:perf:agent-profiling")
+
+echo "Removing leftover monitoring files from past runs"
+rm monitor-data/*
+
+for cmd in "${commands[@]}"; do
+  # Start the app in the background
+  echo "Starting app with $cmd"
+  npm run "$cmd" &
+  APP_PID=$!
+
+  # Wait for the server to start (adjust as needed)
+  sleep 10
+
+  echo "Injecting traffic for $RUN_TIME minutes"
+  hey -z "$RUN_TIME"m http://localhost:3000/named-route
+
+  # After hey completes, stop the app
+  kill $APP_PID
+  # Determine output filename
+  case "$cmd" in
+    "start:perf:no-agent") out="perf-data-no-agent.csv" ;;
+    "start:perf:agent-no-profiling") out="perf-data-agent-no-profiling.csv" ;;
+    "start:perf:agent-profiling") out="perf-data-agent-profiling.csv" ;;
+  esac
+
+  echo "moving file to $out"
+  # Find the most recent CSV file in monitor-data and rename it
+  # Using /bin/ls because my shell alias ls to some other cli tool
+  CSV_FILE=$(/bin/ls -t monitor-data/*.csv | head -n 1)
+  mv "$CSV_FILE" monitor-data/"$out"
+  echo "done, onto the next"
+done
diff --git a/simple-express-app/v8-monitor.js b/simple-express-app/v8-monitor.js
@@ -0,0 +1,115 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const fs = require('node:fs/promises')
+const path = require('node:path')
+
+const SAMPLE_INTERVAL = 1000 // ms
+const WARMUP_DURATION = 5000 // ms (default warmup)
+const OUTPUT_FILE = `v8-monitor-${Date.now()}.csv`
+const MONITORING_DIR = path.join(__dirname, 'monitor-data')
+const FILE_PATH = path.join(MONITORING_DIR, OUTPUT_FILE)
+
+function getCpuUsage(prevCpu) {
+  // Get CPU usage delta from process
+  const usage = process.cpuUsage(prevCpu)
+  const formatted = {
+    user: usage.user / 1000,
+    system: usage.system / 1000,
+  }
+  return {
+    raw: usage,
+    formatted,
+  }
+}
+
+function getMemoryUsage() {
+  const mem = process.memoryUsage()
+  return {
+    rss: mem.rss,
+    heapTotal: mem.heapTotal,
+    heapUsed: mem.heapUsed,
+  }
+}
+
+async function writeHeader() {
+  try {
+    await fs.mkdir(MONITORING_DIR)
+  } catch {}
+
+  const header = [
+    'timestamp',
+    'cpu_user_ms',
+    'cpu_system_ms',
+    'cpuUserPercent',
+    'cpuSystemPercent',
+    'rss',
+    'heapTotal',
+    'heapUsed',
+    'heapUsedPercent',
+  ].join(',') + '\n'
+
+  return fs.writeFile(FILE_PATH, header)
+}
+
+async function writeSample(data) {
+  const heapUsedPercent = data.memory.heapTotal > 0 ? (data.memory.heapUsed / data.memory.heapTotal) * 100 : 0
+  // cpu.user and cpu.system are now percent per core
+  const cpuUserPercent = data.cpu.user
+  const cpuSystemPercent = data.cpu.system
+  const line = [
+    data.timestamp,
+    data.cpu.user,
+    data.cpu.system,
+    cpuUserPercent,
+    cpuSystemPercent,
+    data.memory.rss,
+    data.memory.heapTotal,
+    data.memory.heapUsed,
+    heapUsedPercent,
+  ].join(',') + '\n'
+  return fs.appendFile(FILE_PATH, line)
+}
+
+let running = false
+async function main() {
+  // eslint-disable-next-line no-console
+  console.log(`Warming up for ${WARMUP_DURATION} ms...`)
+  await writeHeader()
+  setTimeout(() => {
+    running = true
+    const prevCpu = process.cpuUsage()
+    process.on('SIGINT', () => {
+      running = false
+      // eslint-disable-next-line no-console
+      console.log('Stopped monitoring.')
+    })
+
+    // eslint-disable-next-line no-console
+    console.log('Starting sampling')
+    sample({ prevCpu })
+  }, WARMUP_DURATION)
+}
+
+async function sample({ prevCpu }) {
+  const now = new Date().toISOString()
+  // Calculate CPU delta since last sample
+  const cpuUsage = getCpuUsage(prevCpu)
+  // Update prevCpu to the current snapshot for next interval
+  prevCpu = process.cpuUsage()
+  const memory = getMemoryUsage()
+  // CPU percent per core
+  const intervalMicros = SAMPLE_INTERVAL * 1000
+  const cpu = {
+    user: (cpuUsage.raw.user / intervalMicros) * 100,
+    system: (cpuUsage.raw.system / intervalMicros) * 100,
+  }
+  await writeSample({ timestamp: now, cpu, memory })
+  if (running) {
+    setTimeout(sample.bind(null, { prevCpu }), SAMPLE_INTERVAL)
+  }
+}
+
+main()