Count JS functions in v8.log

function_count.js

#!/usr/bin/env node
var fs = require('fs');
var file = process.argv.length > 2 ? process.argv[2] : 'v8.log';
var log = fs.createReadStream(file, {
  flags: 'r',
  encoding: 'utf8',
  autoClose: true
});

var pattern = /\<JS Function (.*) \(SharedFunctionInfo 0x[a-f0-9]+\)\>/gi
var entries = [];
var map = Object.create(null);
var buffer = '';

function processString(str) {
  var match;
  pattern.lastIndex = 0;
  while (match = pattern.exec(buffer)) {
    var name = match[1];
    var entry = map[name];
    if (entry === undefined) {
      entry = { name: name, count: 1 }
      entries.push(entry);
      map[name] = entry;
    } else {
      entry.count++;
    }
  }
}

log.on('data', function (chunk) {
  var newline = chunk.lastIndexOf("\n");
  if (newline === -1) {
    buffer += chunk;
    return;
  }

  buffer += chunk.substring(0, newline);

  processString(buffer);

  buffer = chunk.substring(newline);
});

log.on('error', function (e) {
  console.error(e);
});

log.on('end', function () {
  processString(buffer);
  entries.sort(function (a, b) {
    return b.count - a.count;
  });
  entries.forEach(function (entry) {
    console.log(entry.name, entry.count);
  });
});

log.resume();

trace.sh

/Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary --no-sandbox --disable-cache --disable-extensions --js-flags="--trace_deopt" http://localhost:8080/ > v8.log