diff --git a/src/daemon/PhutilDaemon.php b/src/daemon/PhutilDaemon.php
index 082421f..a0aaf56 100644
--- a/src/daemon/PhutilDaemon.php
+++ b/src/daemon/PhutilDaemon.php
@@ -1,383 +1,383 @@
 <?php
 
 /**
  * Scaffolding for implementing robust background processing scripts.
  *
  *
  * Autoscaling
  * ===========
  *
  * Autoscaling automatically launches copies of a daemon when it is busy
  * (scaling the pool up) and stops them when they're idle (scaling the pool
  * down). This is appropriate for daemons which perform highly parallelizable
  * work.
  *
  * To make a daemon support autoscaling, the implementation should look
  * something like this:
  *
  *   while (!$this->shouldExit()) {
  *     if (work_available()) {
  *       $this->willBeginWork();
  *       do_work();
  *       $this->sleep(0);
  *     } else {
  *       $this->willBeginIdle();
  *       $this->sleep(1);
  *     }
  *   }
  *
  * In particular, call @{method:willBeginWork} before becoming busy, and
  * @{method:willBeginIdle} when no work is available. If the daemon is launched
  * into an autoscale pool, this will cause the pool to automatically scale up
  * when busy and down when idle.
  *
  * See @{class:PhutilHighIntensityIntervalDaemon} for an example of a simple
  * autoscaling daemon.
  *
  * Launching a daemon which does not make these callbacks into an autoscale
  * pool will have no effect.
  *
  * @task overseer Communicating With the Overseer
  * @task autoscale Autoscaling Daemon Pools
  */
 abstract class PhutilDaemon extends Phobject {
 
   const MESSAGETYPE_STDOUT = 'stdout';
   const MESSAGETYPE_HEARTBEAT = 'heartbeat';
   const MESSAGETYPE_BUSY = 'busy';
   const MESSAGETYPE_IDLE = 'idle';
   const MESSAGETYPE_DOWN = 'down';
   const MESSAGETYPE_HIBERNATE = 'hibernate';
 
   const WORKSTATE_BUSY = 'busy';
   const WORKSTATE_IDLE = 'idle';
 
   private $argv;
   private $traceMode;
   private $traceMemory;
   private $verbose;
   private $notifyReceived;
   private $inGracefulShutdown;
   private $workState = null;
   private $idleSince = null;
   private $scaledownDuration;
 
   final public function setVerbose($verbose) {
     $this->verbose = $verbose;
     return $this;
   }
 
   final public function getVerbose() {
     return $this->verbose;
   }
 
   final public function setScaledownDuration($scaledown_duration) {
     $this->scaledownDuration = $scaledown_duration;
     return $this;
   }
 
   final public function getScaledownDuration() {
     return $this->scaledownDuration;
   }
 
   final public function __construct(array $argv) {
     $this->argv = $argv;
 
     $router = PhutilSignalRouter::getRouter();
     $handler_key = 'daemon.term';
     if (!$router->getHandler($handler_key)) {
       $handler = new PhutilCallbackSignalHandler(
         SIGTERM,
         __CLASS__.'::onTermSignal');
       $router->installHandler($handler_key, $handler);
     }
 
     pcntl_signal(SIGINT, array($this, 'onGracefulSignal'));
     pcntl_signal(SIGUSR2, array($this, 'onNotifySignal'));
 
     // Without discard mode, this consumes unbounded amounts of memory. Keep
     // memory bounded.
     PhutilServiceProfiler::getInstance()->enableDiscardMode();
 
     $this->beginStdoutCapture();
   }
 
   final public function __destruct() {
     $this->endStdoutCapture();
   }
 
   final public function stillWorking() {
     $this->emitOverseerMessage(self::MESSAGETYPE_HEARTBEAT, null);
 
     if ($this->traceMemory) {
       $daemon = get_class($this);
       fprintf(
         STDERR,
         "%s %s %s\n",
         '<RAMS>',
         $daemon,
         pht(
           'Memory Usage: %s KB',
           new PhutilNumber(memory_get_usage() / 1024, 1)));
     }
   }
 
   final public function shouldExit() {
     return $this->inGracefulShutdown;
   }
 
   final protected function shouldHibernate($duration) {
     // Don't hibernate if we don't have very long to sleep.
     if ($duration < 5) {
       return false;
     }
 
     // Never hibernate if we're part of a pool and could scale down instead.
     // We only hibernate the last process to drop the pool size to zero.
     if ($this->getScaledownDuration()) {
       return false;
     }
 
     // Don't hibernate for too long.
-    $duration = max($duration, phutil_units('3 minutes in seconds'));
+    $duration = min($duration, phutil_units('3 minutes in seconds'));
 
     $this->emitOverseerMessage(
       self::MESSAGETYPE_HIBERNATE,
       array(
         'duration' => $duration,
       ));
 
     $this->log(
       pht(
         'Preparing to hibernate for %s second(s).',
         new PhutilNumber($duration)));
 
     return true;
   }
 
   final protected function sleep($duration) {
     $this->notifyReceived = false;
     $this->willSleep($duration);
     $this->stillWorking();
 
     $scale_down = $this->getScaledownDuration();
 
     $max_sleep = 60;
     if ($scale_down) {
       $max_sleep = min($max_sleep, $scale_down);
     }
 
     if ($scale_down) {
       if ($this->workState == self::WORKSTATE_IDLE) {
         $dur = (time() - $this->idleSince);
         $this->log(pht('Idle for %s seconds.', $dur));
       }
     }
 
     while ($duration > 0 &&
       !$this->notifyReceived &&
       !$this->shouldExit()) {
 
       // If this is an autoscaling clone and we've been idle for too long,
       // we're going to scale the pool down by exiting and not restarting. The
       // DOWN message tells the overseer that we don't want to be restarted.
       if ($scale_down) {
         if ($this->workState == self::WORKSTATE_IDLE) {
           if ($this->idleSince && ($this->idleSince + $scale_down < time())) {
             $this->inGracefulShutdown = true;
             $this->emitOverseerMessage(self::MESSAGETYPE_DOWN, null);
             $this->log(
               pht(
                 'Daemon was idle for more than %s second(s), '.
                 'scaling pool down.',
                 new PhutilNumber($scale_down)));
             break;
           }
         }
       }
 
       sleep(min($duration, $max_sleep));
       $duration -= $max_sleep;
       $this->stillWorking();
     }
   }
 
   protected function willSleep($duration) {
     return;
   }
 
   public static function onTermSignal($signo) {
     self::didCatchSignal($signo);
   }
 
   final protected function getArgv() {
     return $this->argv;
   }
 
   final public function execute() {
     $this->willRun();
     $this->run();
   }
 
   abstract protected function run();
 
   final public function setTraceMemory() {
     $this->traceMemory = true;
     return $this;
   }
 
   final public function getTraceMemory() {
     return $this->traceMemory;
   }
 
   final public function setTraceMode() {
     $this->traceMode = true;
     PhutilServiceProfiler::installEchoListener();
     PhutilConsole::getConsole()->getServer()->setEnableLog(true);
     $this->didSetTraceMode();
     return $this;
   }
 
   final public function getTraceMode() {
     return $this->traceMode;
   }
 
   final public function onGracefulSignal($signo) {
     self::didCatchSignal($signo);
     $this->inGracefulShutdown = true;
   }
 
   final public function onNotifySignal($signo) {
     self::didCatchSignal($signo);
     $this->notifyReceived = true;
     $this->onNotify($signo);
   }
 
   protected function onNotify($signo) {
     // This is a hook for subclasses.
   }
 
   protected function willRun() {
     // This is a hook for subclasses.
   }
 
   protected function didSetTraceMode() {
     // This is a hook for subclasses.
   }
 
   final protected function log($message) {
     if ($this->verbose) {
       $daemon = get_class($this);
       fprintf(STDERR, "%s %s %s\n", '<VERB>', $daemon, $message);
     }
   }
 
   private static function didCatchSignal($signo) {
     $signame = phutil_get_signal_name($signo);
     fprintf(
       STDERR,
       "%s Caught signal %s (%s).\n",
       '<SGNL>',
       $signo,
       $signame);
   }
 
 
 /* -(  Communicating With the Overseer  )------------------------------------ */
 
 
   private function beginStdoutCapture() {
     ob_start(array($this, 'didReceiveStdout'), 2);
   }
 
   private function endStdoutCapture() {
     ob_end_flush();
   }
 
   public function didReceiveStdout($data) {
     if (!strlen($data)) {
       return '';
     }
 
     return $this->encodeOverseerMessage(self::MESSAGETYPE_STDOUT, $data);
   }
 
   private function encodeOverseerMessage($type, $data) {
     $structure = array($type);
 
     if ($data !== null) {
       $structure[] = $data;
     }
 
     return json_encode($structure)."\n";
   }
 
   private function emitOverseerMessage($type, $data) {
     $this->endStdoutCapture();
     echo $this->encodeOverseerMessage($type, $data);
     $this->beginStdoutCapture();
   }
 
   public static function errorListener($event, $value, array $metadata) {
     // If the caller has redirected the error log to a file, PHP won't output
     // messages to stderr, so the overseer can't capture them. Install a
     // listener which just  echoes errors to stderr, so the overseer is always
     // aware of errors.
 
     $console = PhutilConsole::getConsole();
     $message = idx($metadata, 'default_message');
 
     if ($message) {
       $console->writeErr("%s\n", $message);
     }
     if (idx($metadata, 'trace')) {
       $trace = PhutilErrorHandler::formatStacktrace($metadata['trace']);
       $console->writeErr("%s\n", $trace);
     }
   }
 
 
 /* -(  Autoscaling  )-------------------------------------------------------- */
 
 
   /**
    * Prepare to become busy. This may autoscale the pool up.
    *
    * This notifies the overseer that the daemon has become busy. If daemons
    * that are part of an autoscale pool are continuously busy for a prolonged
    * period of time, the overseer may scale up the pool.
    *
    * @return this
    * @task autoscale
    */
   protected function willBeginWork() {
     if ($this->workState != self::WORKSTATE_BUSY) {
       $this->workState = self::WORKSTATE_BUSY;
       $this->idleSince = null;
       $this->emitOverseerMessage(self::MESSAGETYPE_BUSY, null);
     }
 
     return $this;
   }
 
 
   /**
    * Prepare to idle. This may autoscale the pool down.
    *
    * This notifies the overseer that the daemon is no longer busy. If daemons
    * that are part of an autoscale pool are idle for a prolonged period of
    * time, they may exit to scale the pool down.
    *
    * @return this
    * @task autoscale
    */
   protected function willBeginIdle() {
     if ($this->workState != self::WORKSTATE_IDLE) {
       $this->workState = self::WORKSTATE_IDLE;
       $this->idleSince = time();
       $this->emitOverseerMessage(self::MESSAGETYPE_IDLE, null);
     }
 
     return $this;
   }
 }
diff --git a/src/daemon/PhutilDaemonOverseer.php b/src/daemon/PhutilDaemonOverseer.php
index e1c1813..bf1f864 100644
--- a/src/daemon/PhutilDaemonOverseer.php
+++ b/src/daemon/PhutilDaemonOverseer.php
@@ -1,514 +1,520 @@
 <?php
 
 /**
  * Oversees a daemon and restarts it if it fails.
  *
  * @task signals Signal Handling
  */
 final class PhutilDaemonOverseer extends Phobject {
 
   private $argv;
   private static $instance;
 
   private $config;
   private $pools = array();
   private $traceMode;
   private $traceMemory;
   private $daemonize;
   private $piddir;
   private $log;
   private $libraries = array();
   private $modules = array();
   private $verbose;
   private $lastPidfile;
   private $startEpoch;
   private $autoscale = array();
   private $autoscaleConfig = array();
 
   const SIGNAL_NOTIFY = 'signal/notify';
   const SIGNAL_RELOAD = 'signal/reload';
   const SIGNAL_GRACEFUL = 'signal/graceful';
   const SIGNAL_TERMINATE = 'signal/terminate';
 
   private $err = 0;
   private $inAbruptShutdown;
   private $inGracefulShutdown;
 
   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);
       }
 
       $sid = posix_setsid();
       if ($sid <= 0) {
         throw new Exception(pht('Failed to create new process session!'));
       }
     }
 
     $this->logMessage(
       'OVER',
       pht(
         'Started new daemon overseer (with PID "%s").',
         getmypid()));
 
     $this->modules = PhutilDaemonOverseerModule::getAllModules();
 
     $this->installSignalHandlers();
   }
 
   public function addLibrary($library) {
     $this->libraries[] = $library;
     return $this;
   }
 
   public function run() {
     $this->createDaemonPools();
 
     while (true) {
       if ($this->shouldReloadDaemons()) {
         $this->didReceiveSignal(SIGHUP);
       }
 
       $futures = array();
+
+      $running_pools = false;
       foreach ($this->getDaemonPools() as $pool) {
         $pool->updatePool();
 
         if (!$this->shouldShutdown()) {
           if ($pool->isHibernating()) {
             if ($this->shouldWakePool($pool)) {
               $pool->wakeFromHibernation();
             }
           }
         }
 
         foreach ($pool->getFutures() as $future) {
           $futures[] = $future;
         }
+
+        if ($pool->getDaemons()) {
+          $running_pools = true;
+        }
       }
 
       $this->updatePidfile();
       $this->updateMemory();
 
       $this->waitForDaemonFutures($futures);
 
-      if (!$futures) {
+      if (!$futures && !$running_pools) {
         if ($this->shouldShutdown()) {
           break;
         }
       }
     }
 
     exit($this->err);
   }
 
 
   private function waitForDaemonFutures(array $futures) {
     assert_instances_of($futures, 'ExecFuture');
 
     if ($futures) {
       // TODO: This only wakes if any daemons actually exit. It would be a bit
       // cleaner to wait on any I/O with Channels.
       $iter = id(new FutureIterator($futures))
         ->setUpdateInterval(1);
       foreach ($iter as $future) {
         break;
       }
     } else {
       if (!$this->shouldShutdown()) {
         sleep(1);
       }
     }
   }
 
   private function createDaemonPools() {
     $configs = $this->config['daemons'];
 
     $forced_options = array(
       'load' => $this->libraries,
       'log' => $this->log,
     );
 
     foreach ($configs as $config) {
       $config = $forced_options + $config;
 
       $pool = PhutilDaemonPool::newFromConfig($config)
         ->setOverseer($this)
         ->setCommandLineArguments($this->argv);
 
       $this->pools[] = $pool;
     }
   }
 
   private function getDaemonPools() {
     return $this->pools;
   }
 
 
   /**
    * 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;
     }
 
     $pidfile = $this->toDictionary();
 
     if ($pidfile !== $this->lastPidfile) {
       $this->lastPidfile = $pidfile;
       $pidfile_path = $this->piddir.'/daemon.'.getmypid();
       Filesystem::writeFile($pidfile_path, phutil_json_encode($pidfile));
     }
   }
 
   public function toDictionary() {
     $daemons = array();
     foreach ($this->getDaemonPools() as $pool) {
       foreach ($pool->getDaemons() as $daemon) {
         if (!$daemon->isRunning()) {
           continue;
         }
 
         $daemons[] = $daemon->toDictionary();
       }
     }
 
     return array(
       'pid' => getmypid(),
       'start' => $this->startEpoch,
       'config' => $this->config,
       'daemons' => $daemons,
     );
   }
 
   private function updateMemory() {
     if (!$this->traceMemory) {
       return;
     }
 
     $this->logMessage(
       'RAMS',
       pht(
         'Overseer Memory Usage: %s KB',
         new PhutilNumber(memory_get_usage() / 1024, 1)));
   }
 
   public function logMessage($type, $message, $context = null) {
     $always_log = false;
     switch ($type) {
       case 'OVER':
       case 'SGNL':
         $always_log = true;
         break;
     }
 
     if ($always_log || $this->traceMode || $this->verbose) {
       error_log(date('Y-m-d g:i:s A').' ['.$type.'] '.$message);
     }
   }
 
 
 /* -(  Signal Handling  )---------------------------------------------------- */
 
 
   /**
    * @task signals
    */
   private function installSignalHandlers() {
     $signals = array(
       SIGUSR2,
       SIGHUP,
       SIGINT,
       SIGTERM,
     );
 
     foreach ($signals as $signal) {
       pcntl_signal($signal, array($this, 'didReceiveSignal'));
     }
   }
 
 
   /**
    * @task signals
    */
   public function didReceiveSignal($signo) {
     $this->logMessage(
       'SGNL',
       pht(
         'Overseer ("%d") received signal %d ("%s").',
         getmypid(),
         $signo,
         phutil_get_signal_name($signo)));
 
     switch ($signo) {
       case SIGUSR2:
         $signal_type = self::SIGNAL_NOTIFY;
         break;
       case SIGHUP:
         $signal_type = self::SIGNAL_RELOAD;
         break;
       case SIGINT:
         // If we receive SIGINT more than once, interpret it like SIGTERM.
         if ($this->inGracefulShutdown) {
           return $this->didReceiveSignal(SIGTERM);
         }
 
         $this->inGracefulShutdown = true;
         $signal_type = self::SIGNAL_GRACEFUL;
         break;
       case SIGTERM:
         // If we receive SIGTERM more than once, terminate abruptly.
         $this->err = 128 + $signo;
         if ($this->inAbruptShutdown) {
           exit($this->err);
         }
 
         $this->inAbruptShutdown = true;
         $signal_type = self::SIGNAL_TERMINATE;
         break;
       default:
         throw new Exception(
           pht(
             'Signal handler called with unknown signal type ("%d")!',
             $signo));
     }
 
     foreach ($this->getDaemonPools() as $pool) {
       $pool->didReceiveSignal($signal_type, $signo);
     }
   }
 
 
 /* -(  Daemon Modules  )----------------------------------------------------- */
 
 
   private function getModules() {
     return $this->modules;
   }
 
   private function shouldReloadDaemons() {
     $modules = $this->getModules();
 
     $should_reload = false;
     foreach ($modules as $module) {
       try {
         // NOTE: Even if one module tells us to reload, we call the method on
         // each module anyway to make calls a little more predictable.
 
         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);
       }
     }
 
     return $should_reload;
   }
 
   private function shouldWakePool(PhutilDaemonPool $pool) {
     $modules = $this->getModules();
 
     $should_wake = false;
     foreach ($modules as $module) {
       try {
         if ($module->shouldWakePool($pool)) {
           $this->logMessage(
             'WAKE',
             pht(
               'Waking pool "%s" (triggered by overseer module "%s").',
               $pool->getPoolLabel(),
               get_class($module)));
           $should_wake = true;
         }
       } catch (Exception $ex) {
         phlog($ex);
       }
     }
 
     return $should_wake;
   }
 
   private function shouldShutdown() {
     return $this->inGracefulShutdown || $this->inAbruptShutdown;
   }
 
 }
diff --git a/src/daemon/PhutilDaemonPool.php b/src/daemon/PhutilDaemonPool.php
index 6d7edf2..50b2228 100644
--- a/src/daemon/PhutilDaemonPool.php
+++ b/src/daemon/PhutilDaemonPool.php
@@ -1,346 +1,360 @@
 <?php
 
 final class PhutilDaemonPool extends Phobject {
 
   private $properties = array();
   private $commandLineArguments;
 
   private $overseer;
   private $daemons = array();
   private $argv;
 
   private $lastAutoscaleUpdate;
   private $inShutdown;
 
   private function __construct() {
     // <empty>
   }
 
   public static function newFromConfig(array $config) {
     PhutilTypeSpec::checkMap(
       $config,
       array(
         'class' => 'string',
         'label' => 'string',
         'argv' => 'optional list<string>',
         'load' => 'optional list<string>',
         'log' => 'optional string|null',
         'pool' => 'optional int',
         'up' => 'optional int',
         'down' => 'optional int',
         'reserve' => 'optional int|float',
       ));
 
     $config = $config + array(
       'argv' => array(),
       'load' => array(),
       'log' => null,
       'pool' => 1,
       'up' => 2,
       'down' => 15,
       'reserve' => 0,
     );
 
     $pool = new self();
     $pool->properties = $config;
 
     return $pool;
   }
 
   public function setOverseer(PhutilDaemonOverseer $overseer) {
     $this->overseer = $overseer;
     return $this;
   }
 
   public function getOverseer() {
     return $this->overseer;
   }
 
   public function setCommandLineArguments(array $arguments) {
     $this->commandLineArguments = $arguments;
     return $this;
   }
 
   public function getCommandLineArguments() {
     return $this->commandLineArguments;
   }
 
   private function shouldShutdown() {
     return $this->inShutdown;
   }
 
   private function newDaemon() {
     $config = $this->properties;
 
     if (count($this->daemons)) {
       $down_duration = $this->getPoolScaledownDuration();
     } else {
       // TODO: For now, never scale pools down to 0.
       $down_duration = 0;
     }
 
     $forced_config = array(
       'down' => $down_duration,
     );
 
     $config = $forced_config + $config;
 
     $config = array_select_keys(
       $config,
       array(
         'class',
         'log',
         'load',
         'argv',
         'down',
       ));
 
     $daemon = PhutilDaemonHandle::newFromConfig($config)
       ->setDaemonPool($this)
       ->setCommandLineArguments($this->getCommandLineArguments());
 
     $daemon_id = $daemon->getDaemonID();
     $this->daemons[$daemon_id] = $daemon;
 
     $daemon->didLaunch();
 
     return $daemon;
   }
 
   public function getDaemons() {
     return $this->daemons;
   }
 
   public function getFutures() {
     $futures = array();
     foreach ($this->getDaemons() as $daemon) {
       $future = $daemon->getFuture();
       if ($future) {
         $futures[] = $future;
       }
     }
 
     return $futures;
   }
 
   public function didReceiveSignal($signal, $signo) {
+    switch ($signal) {
+      case PhutilDaemonOverseer::SIGNAL_GRACEFUL:
+      case PhutilDaemonOverseer::SIGNAL_TERMINATE:
+        $this->inShutdown = true;
+        break;
+    }
+
     foreach ($this->getDaemons() as $daemon) {
       switch ($signal) {
         case PhutilDaemonOverseer::SIGNAL_NOTIFY:
           $daemon->didReceiveNotifySignal($signo);
           break;
         case PhutilDaemonOverseer::SIGNAL_RELOAD:
           $daemon->didReceiveReloadSignal($signo);
           break;
         case PhutilDaemonOverseer::SIGNAL_GRACEFUL:
-          $this->inShutdown = true;
           $daemon->didReceiveGracefulSignal($signo);
           break;
         case PhutilDaemonOverseer::SIGNAL_TERMINATE:
-          $this->inShutdown = true;
           $daemon->didReceiveTerminateSignal($signo);
           break;
         default:
           throw new Exception(
             pht(
               'Unknown signal "%s" ("%d").',
               $signal,
               $signo));
       }
     }
   }
 
   public function getPoolLabel() {
     return $this->getPoolProperty('label');
   }
 
   public function getPoolMaximumSize() {
     return $this->getPoolProperty('pool');
   }
 
   public function getPoolScaleupDuration() {
     return $this->getPoolProperty('up');
   }
 
   public function getPoolScaledownDuration() {
     return $this->getPoolProperty('down');
   }
 
   public function getPoolMemoryReserve() {
     return $this->getPoolProperty('reserve');
   }
 
   public function getPoolDaemonClass() {
     return $this->getPoolProperty('class');
   }
 
   private function getPoolProperty($key) {
     return idx($this->properties, $key);
   }
 
   public function updatePool() {
     $daemons = $this->getDaemons();
 
     foreach ($daemons as $key => $daemon) {
       $daemon->update();
 
       if ($daemon->isDone()) {
         $daemon->didExit();
 
         unset($this->daemons[$key]);
 
-        $this->logMessage(
-          'POOL',
-          pht(
-            'Autoscale pool "%s" scaled down to %s daemon(s).',
-            $this->getPoolLabel(),
-            new PhutilNumber(count($this->daemons))));
+        if ($this->shouldShutdown()) {
+          $this->logMessage(
+            'DOWN',
+            pht(
+              'Pool "%s" is exiting, with %s daemon(s) remaining.',
+              $this->getPoolLabel(),
+              new PhutilNumber(count($this->daemons))));
+        } else {
+          $this->logMessage(
+            'POOL',
+            pht(
+              'Autoscale pool "%s" scaled down to %s daemon(s).',
+              $this->getPoolLabel(),
+              new PhutilNumber(count($this->daemons))));
+        }
       }
     }
 
     $this->updateAutoscale();
   }
 
   public function isHibernating() {
     foreach ($this->getDaemons() as $daemon) {
       if (!$daemon->isHibernating()) {
         return false;
       }
     }
 
     return true;
   }
 
   public function wakeFromHibernation() {
     if (!$this->isHibernating()) {
       return $this;
     }
 
     $this->logMessage(
       'WAKE',
       pht(
         'Autoscale pool "%s" is being awakened from hibernation.',
         $this->getPoolLabel()));
 
     $did_wake_daemons = false;
     foreach ($this->getDaemons() as $daemon) {
       if ($daemon->isHibernating()) {
         $daemon->wakeFromHibernation();
         $did_wake_daemons = true;
       }
     }
 
     if (!$did_wake_daemons) {
       // TODO: Pools currently can't scale down to 0 daemons, but we should
       // scale up immediately here once they can.
     }
 
     $this->updatePool();
 
     return $this;
   }
 
   private function updateAutoscale() {
     if ($this->shouldShutdown()) {
       return;
     }
 
     // Don't try to autoscale more than once per second. This mostly stops the
     // logs from getting flooded in verbose mode.
     $now = time();
     if ($this->lastAutoscaleUpdate >= $now) {
       return;
     }
     $this->lastAutoscaleUpdate = $now;
 
     $daemons = $this->getDaemons();
 
     // If this pool is already at the maximum size, we can't launch any new
     // daemons.
     $max_size = $this->getPoolMaximumSize();
     if (count($daemons) >= $max_size) {
       $this->logMessage(
         'POOL',
         pht(
           'Autoscale pool "%s" already at maximum size (%s of %s).',
           $this->getPoolLabel(),
           new PhutilNumber(count($daemons)),
           new PhutilNumber($max_size)));
       return;
     }
 
     $scaleup_duration = $this->getPoolScaleupDuration();
 
     foreach ($daemons as $daemon) {
       $busy_epoch = $daemon->getBusyEpoch();
       // If any daemons haven't started work yet, don't scale the pool up.
       if (!$busy_epoch) {
         $this->logMessage(
           'POOL',
           pht(
             'Autoscale pool "%s" has an idle daemon, declining to scale.',
             $this->getPoolLabel()));
         return;
       }
 
       // If any daemons started work very recently, wait a little while
       // to scale the pool up.
       $busy_for = ($now - $busy_epoch);
       if ($busy_for < $scaleup_duration) {
         $this->logMessage(
           'POOL',
           pht(
             'Autoscale pool "%s" has not been busy long enough to scale up '.
             '(busy for %s of %s seconds).',
             $this->getPoolLabel(),
             new PhutilNumber($busy_for),
             new PhutilNumber($scaleup_duration)));
         return;
       }
     }
 
     // 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).
 
     // Note that the first daemon is exempt: we'll always launch at least one
     // daemon, regardless of any memory reservation.
     if (count($daemons)) {
       $reserve = $this->getPoolMemoryReserve();
       if ($reserve) {
         // On some systems this may be slightly more expensive than other
         // checks, so we 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) {
           $this->logMessage(
             'POOL',
             pht(
               'Autoscale pool "%s" does not have enough free memory to '.
               'scale up (%s free of %s reserved).',
               $this->getPoolLabel(),
               new PhutilNumber($free_ratio, 3),
               new PhutilNumber($reserve, 3)));
           return;
         }
       }
     }
 
     $this->logMessage(
       'AUTO',
       pht(
         'Scaling pool "%s" up to %s daemon(s).',
         $this->getPoolLabel(),
         new PhutilNumber(count($daemons) + 1)));
 
     $this->newDaemon();
   }
 
   public function logMessage($type, $message, $context = null) {
     return $this->getOverseer()->logMessage($type, $message, $context);
   }
 
 }