android-heap-logger.js

var spawn = require('child_process').spawn;

function Log(level, pid, message) {
  this.level = level;
  this.pid = pid;
  this.message = message;
}

process.stdout.write(['time', 'mem_freed', 'allocated', 'size'].join('\t') + '\n');

function onLog(log) {
  if (log.pid != process.argv[2]) return;
  if (log.message.indexOf('GC_')) return;

  var parts = log.message.match(/GC_([A-Z_]*) freed ([0-9]*)K, [0-9]*% free ([0-9]*)K\/([0-9]*)K/);
  if (!parts) return;

  process.stdout.write(process.hrtime()[0] + '\t');
  process.stdout.write(parts.slice(2).join('\t') + '\n');
}

function parseLogLine(line) {
  var parts = line.match(/([VDWE])\(([0-9 ]*)\)(.*)/);
  if (!parts) return null;

  var log = new Log(parts[1], parts[2].trim(), parts[3].trim());
  onLog(log);
}

var logcat = spawn('adb', ['logcat', '-v', 'process']);
logcat.stdout.on('data', function(data) {
  data.toString().trim().split(/\r?\n/).forEach(parseLogLine);
});