diff --git a/src/daemon/PhutilDaemonOverseer.php b/src/daemon/PhutilDaemonOverseer.php
index adf9928..14d9b3f 100644
--- a/src/daemon/PhutilDaemonOverseer.php
+++ b/src/daemon/PhutilDaemonOverseer.php
@@ -1,516 +1,536 @@
 <?php
 
 /**
  * Oversees a daemon and restarts it if it fails.
  */
 final class PhutilDaemonOverseer extends Phobject {
 
   private $argv;
   private $moreArgs;
   private $inAbruptShutdown;
   private $inGracefulShutdown;
   private static $instance;
 
   private $config;
   private $daemons = array();
   private $traceMode;
   private $traceMemory;
   private $daemonize;
   private $piddir;
   private $log;
   private $libraries = array();
   private $modules = array();
   private $verbose;
   private $err = 0;
   private $lastPidfile;
   private $startEpoch;
   private $autoscale = array();
+  private $autoscaleConfig = array();
 
   public function __construct(array $argv) {
     PhutilServiceProfiler::getInstance()->enableDiscardMode();
 
     $args = new PhutilArgumentParser($argv);
     $args->setTagline(pht('daemon overseer'));
     $args->setSynopsis(<<<EOHELP
 **launch_daemon.php** [__options__] __daemon__
     Launch and oversee an instance of __daemon__.
 EOHELP
       );
     $args->parseStandardArguments();
     $args->parse(
       array(
         array(
           'name' => 'trace-memory',
           'help' => pht('Enable debug memory tracing.'),
         ),
         array(
           'name'  => 'verbose',
           'help'  => pht('Enable verbose activity logging.'),
         ),
         array(
           'name' => 'label',
           'short' => 'l',
           'param' => 'label',
           'help' => pht(
             'Optional process label. Makes "%s" nicer, no behavioral effects.',
             'ps'),
         ),
       ));
     $argv = array();
 
     if ($args->getArg('trace')) {
       $this->traceMode = true;
       $argv[] = '--trace';
     }
 
     if ($args->getArg('trace-memory')) {
       $this->traceMode = true;
       $this->traceMemory = true;
       $argv[] = '--trace-memory';
     }
     $verbose = $args->getArg('verbose');
     if ($verbose) {
       $this->verbose = true;
       $argv[] = '--verbose';
     }
 
     $label = $args->getArg('label');
     if ($label) {
       $argv[] = '-l';
       $argv[] = $label;
     }
 
     $this->argv = $argv;
 
     if (function_exists('posix_isatty') && posix_isatty(STDIN)) {
       fprintf(STDERR, pht('Reading daemon configuration from stdin...')."\n");
     }
     $config = @file_get_contents('php://stdin');
     $config = id(new PhutilJSONParser())->parse($config);
 
     $this->libraries = idx($config, 'load');
     $this->log = idx($config, 'log');
     $this->daemonize = idx($config, 'daemonize');
     $this->piddir = idx($config, 'piddir');
 
     $this->config = $config;
 
     if (self::$instance) {
       throw new Exception(
         pht('You may not instantiate more than one Overseer per process.'));
     }
 
     self::$instance = $this;
 
     $this->startEpoch = time();
 
     // Check this before we daemonize, since if it's an issue the child will
     // exit immediately.
     if ($this->piddir) {
       $dir = $this->piddir;
       try {
         Filesystem::assertWritable($dir);
       } catch (Exception $ex) {
         throw new Exception(
           pht(
             "Specified daemon PID directory ('%s') does not exist or is ".
             "not writable by the daemon user!",
             $dir));
       }
     }
 
     if (!idx($config, 'daemons')) {
       throw new PhutilArgumentUsageException(
         pht('You must specify at least one daemon to start!'));
     }
 
     if ($this->log) {
       // NOTE: Now that we're committed to daemonizing, redirect the error
       // log if we have a `--log` parameter. Do this at the last moment
       // so as many setup issues as possible are surfaced.
       ini_set('error_log', $this->log);
     }
 
     if ($this->daemonize) {
       // We need to get rid of these or the daemon will hang when we TERM it
       // waiting for something to read the buffers. TODO: Learn how unix works.
       fclose(STDOUT);
       fclose(STDERR);
       ob_start();
 
       $pid = pcntl_fork();
       if ($pid === -1) {
         throw new Exception(pht('Unable to fork!'));
       } else if ($pid) {
         exit(0);
       }
     }
 
     $this->modules = PhutilDaemonOverseerModule::getAllModules();
 
     pcntl_signal(SIGUSR2, array($this, 'didReceiveNotifySignal'));
 
     pcntl_signal(SIGHUP,  array($this, 'didReceiveReloadSignal'));
     pcntl_signal(SIGINT,  array($this, 'didReceiveGracefulSignal'));
     pcntl_signal(SIGTERM, array($this, 'didReceiveTerminalSignal'));
   }
 
   public function addLibrary($library) {
     $this->libraries[] = $library;
     return $this;
   }
 
   public function run() {
     $this->daemons = array();
 
     foreach ($this->config['daemons'] as $config) {
       $config += array(
         'argv' => array(),
         'autoscale' => array(),
       );
 
       $daemon = new PhutilDaemonHandle(
         $this,
         $config['class'],
         $this->argv,
         array(
           'log' => $this->log,
           'argv' => $config['argv'],
           'load' => $this->libraries,
           'autoscale' => $config['autoscale'],
         ));
 
       $daemon->setTraceMemory($this->traceMemory);
 
       $this->addDaemon($daemon, $config);
+
+      $group = idx($config['autoscale'], 'group');
+      if (strlen($group)) {
+        if (isset($this->autoscaleConfig[$group])) {
+          throw new Exception(
+            pht(
+              'Two daemons are part of the same autoscale group ("%s"). '.
+              'Each daemon autoscale group must be unique.',
+              $group));
+        }
+        $this->autoscaleConfig[$group] = $config;
+      }
     }
 
     $should_reload = false;
 
     while (true) {
       foreach ($this->modules as $module) {
         try {
           if ($module->shouldReloadDaemons()) {
             $this->logMessage(
               'RELO',
               pht(
                 'Reloading daemons (triggered by overseer module "%s").',
                 get_class($module)));
             $should_reload = true;
           }
         } catch (Exception $ex) {
           phlog($ex);
         }
       }
 
       if ($should_reload) {
         $this->didReceiveReloadSignal(SIGHUP);
         $should_reload = false;
       }
 
       $futures = array();
       foreach ($this->getDaemonHandles() as $daemon) {
         $daemon->update();
         if ($daemon->isRunning()) {
           $futures[] = $daemon->getFuture();
         }
 
         if ($daemon->isDone()) {
           $this->removeDaemon($daemon);
         }
       }
 
       $this->updatePidfile();
       $this->updateAutoscale();
 
       if ($futures) {
         $iter = id(new FutureIterator($futures))
           ->setUpdateInterval(1);
         foreach ($iter as $future) {
           break;
         }
       } else {
         if ($this->inGracefulShutdown) {
           break;
         }
         sleep(1);
       }
     }
 
     exit($this->err);
   }
 
   private function addDaemon(PhutilDaemonHandle $daemon, array $config) {
     $id = $daemon->getDaemonID();
     $this->daemons[$id] = array(
       'handle' => $daemon,
       'config' => $config,
     );
 
     $autoscale_group = $this->getAutoscaleGroup($daemon);
     if ($autoscale_group) {
       $this->autoscale[$autoscale_group][$id] = true;
     }
 
     return $this;
   }
 
   private function removeDaemon(PhutilDaemonHandle $daemon) {
     $id = $daemon->getDaemonID();
 
     $autoscale_group = $this->getAutoscaleGroup($daemon);
     if ($autoscale_group) {
       unset($this->autoscale[$autoscale_group][$id]);
     }
 
     unset($this->daemons[$id]);
 
     $daemon->didRemoveDaemon();
 
     return $this;
   }
 
   private function getAutoscaleGroup(PhutilDaemonHandle $daemon) {
-    return $this->getAutoscaleProperty($daemon, 'group');
-  }
-
-  private function getAutoscaleProperty(
-    PhutilDaemonHandle $daemon,
-    $key,
-    $default = null) {
-
     $id = $daemon->getDaemonID();
     $autoscale = $this->daemons[$id]['config']['autoscale'];
-    return idx($autoscale, $key, $default);
+    return idx($autoscale, 'group');
+  }
+
+  private function getAutoscaleProperty($group_key, $key, $default = null) {
+    $config = $this->autoscaleConfig[$group_key]['autoscale'];
+    return idx($config, $key, $default);
   }
 
   public function didBeginWork(PhutilDaemonHandle $daemon) {
     $id = $daemon->getDaemonID();
     $busy = idx($this->daemons[$daemon->getDaemonID()], 'busy');
     if (!$busy) {
       $this->daemons[$id]['busy'] = time();
     }
   }
 
   public function didBeginIdle(PhutilDaemonHandle $daemon) {
     $id = $daemon->getDaemonID();
     unset($this->daemons[$id]['busy']);
   }
 
   public function updateAutoscale() {
+    if ($this->inGracefulShutdown) {
+      return;
+    }
+
     foreach ($this->autoscale as $group => $daemons) {
-      $daemon = $this->daemons[head_key($daemons)]['handle'];
-      $scaleup_duration = $this->getAutoscaleProperty($daemon, 'up', 2);
-      $max_pool_size = $this->getAutoscaleProperty($daemon, 'pool', 8);
-      $reserve = $this->getAutoscaleProperty($daemon, 'reserve', 0);
+      $scaleup_duration = $this->getAutoscaleProperty($group, 'up', 2);
+      $max_pool_size = $this->getAutoscaleProperty($group, 'pool', 8);
+      $reserve = $this->getAutoscaleProperty($group, 'reserve', 0);
 
       // Don't scale a group if it is already at the maximum pool size.
       if (count($daemons) >= $max_pool_size) {
         continue;
       }
 
       $should_scale = true;
       foreach ($daemons as $daemon_id => $ignored) {
         $busy = idx($this->daemons[$daemon_id], 'busy');
         if (!$busy) {
           // At least one daemon in the group hasn't reported that it has
           // started work.
           $should_scale = false;
           break;
         }
 
         if ((time() - $busy) < $scaleup_duration) {
           // At least one daemon in the group was idle recently, so we have
           // not fullly
           $should_scale = false;
           break;
         }
       }
 
       // If we have a configured memory reserve for this pool, it tells us that
       // we should not scale up unless there's at least that much memory left
       // on the system (for example, a reserve of 0.25 means that 25% of system
       // memory must be free to autoscale).
       if ($should_scale && $reserve) {
         // On some systems this may be slightly more expensive than other
         // checks, so only do it once we're prepared to scale up.
         $memory = PhutilSystem::getSystemMemoryInformation();
         $free_ratio = ($memory['free'] / $memory['total']);
 
         // If we don't have enough free memory, don't scale.
         if ($free_ratio <= $reserve) {
           continue;
         }
       }
 
       if ($should_scale) {
-        $config = $this->daemons[$daemon_id]['config'];
+        $config = $this->autoscaleConfig[$group];
 
         $config['autoscale']['clone'] = true;
 
         $clone = new PhutilDaemonHandle(
           $this,
           $config['class'],
           $this->argv,
           array(
             'log' => $this->log,
             'argv' => $config['argv'],
             'load' => $this->libraries,
             'autoscale' => $config['autoscale'],
           ));
 
+        $this->logMessage(
+          'AUTO',
+          pht(
+            'Scaling pool "%s" up to %s daemon(s).',
+            $group,
+            new PhutilNumber(count($daemons) + 1)));
+
         $this->addDaemon($clone, $config);
 
         // Don't scale more than one pool up per iteration. Otherwise, we could
         // break the memory barrier if we have a lot of pools and scale them
         // all up at once.
         return;
       }
     }
   }
 
   public function didReceiveNotifySignal($signo) {
     foreach ($this->getDaemonHandles() as $daemon) {
       $daemon->didReceiveNotifySignal($signo);
     }
   }
 
   public function didReceiveReloadSignal($signo) {
     foreach ($this->getDaemonHandles() as $daemon) {
       $daemon->didReceiveReloadSignal($signo);
     }
   }
 
   public function didReceiveGracefulSignal($signo) {
     // If we receive SIGINT more than once, interpret it like SIGTERM.
     if ($this->inGracefulShutdown) {
       return $this->didReceiveTerminalSignal($signo);
     }
     $this->inGracefulShutdown = true;
 
     foreach ($this->getDaemonHandles() as $daemon) {
       $daemon->didReceiveGracefulSignal($signo);
     }
   }
 
   public function didReceiveTerminalSignal($signo) {
     $this->err = 128 + $signo;
     if ($this->inAbruptShutdown) {
       exit($this->err);
     }
     $this->inAbruptShutdown = true;
 
     foreach ($this->getDaemonHandles() as $daemon) {
       $daemon->didReceiveTerminalSignal($signo);
     }
   }
 
   private function getDaemonHandles() {
     return ipull($this->daemons, 'handle');
   }
 
   /**
    * Identify running daemons by examining the process table. This isn't
    * completely reliable, but can be used as a fallback if the pid files fail
    * or we end up with stray daemons by other means.
    *
    * Example output (array keys are process IDs):
    *
    *   array(
    *     12345 => array(
    *       'type' => 'overseer',
    *       'command' => 'php launch_daemon.php --daemonize ...',
    *       'pid' => 12345,
    *     ),
    *     12346 => array(
    *       'type' => 'daemon',
    *       'command' => 'php exec_daemon.php ...',
    *       'pid' => 12346,
    *     ),
    *  );
    *
    * @return dict   Map of PIDs to process information, identifying running
    *                daemon processes.
    */
   public static function findRunningDaemons() {
     $results = array();
 
     list($err, $processes) = exec_manual('ps -o pid,command -a -x -w -w -w');
     if ($err) {
       return $results;
     }
 
     $processes = array_filter(explode("\n", trim($processes)));
     foreach ($processes as $process) {
       list($pid, $command) = preg_split('/\s+/', trim($process), 2);
 
       $pattern = '/((launch|exec)_daemon.php|phd-daemon)/';
       $matches = null;
       if (!preg_match($pattern, $command, $matches)) {
         continue;
       }
 
       switch ($matches[1]) {
         case 'exec_daemon.php':
           $type = 'daemon';
           break;
         case 'launch_daemon.php':
         case 'phd-daemon':
         default:
           $type = 'overseer';
           break;
       }
 
       $results[(int)$pid] = array(
         'type' => $type,
         'command' => $command,
         'pid' => (int)$pid,
       );
     }
 
     return $results;
   }
 
   private function updatePidfile() {
     if (!$this->piddir) {
       return;
     }
 
     $daemons = array();
 
     foreach ($this->daemons as $daemon) {
       $handle = $daemon['handle'];
       $config = $daemon['config'];
 
       if (!$handle->isRunning()) {
         continue;
       }
 
       $daemons[] = array(
         'pid' => $handle->getPID(),
         'id' => $handle->getDaemonID(),
         'config' => $config,
       );
     }
 
     $pidfile = array(
       'pid' => getmypid(),
       'start' => $this->startEpoch,
       'config' => $this->config,
       'daemons' => $daemons,
     );
 
     if ($pidfile !== $this->lastPidfile) {
       $this->lastPidfile = $pidfile;
       $pidfile_path = $this->piddir.'/daemon.'.getmypid();
       Filesystem::writeFile($pidfile_path, json_encode($pidfile));
     }
   }
 
   public function logMessage($type, $message, $context = null) {
     if ($this->traceMode || $this->verbose) {
       error_log(date('Y-m-d g:i:s A').' ['.$type.'] '.$message);
     }
   }
 
 }