diff --git a/bin/brozzler-worker b/bin/brozzler-worker
index 47de730..d1be9cd 100755
--- a/bin/brozzler-worker
+++ b/bin/brozzler-worker
@@ -35,10 +35,6 @@ args = arg_parser.parse_args(args=sys.argv[1:])
 logging.basicConfig(stream=sys.stdout, level=args.log_level,
         format='%(asctime)s %(process)d %(levelname)s %(threadName)s %(name)s.%(funcName)s(%(filename)s:%(lineno)d) %(message)s')
 
-browsers = set()
-browsers_lock = threading.Lock()
-num_browsers = 0
-
 shutdown_requested = threading.Event()
 
 def next_url(site):
@@ -51,34 +47,39 @@ def next_url(site):
         msg.ack()
         return crawl_url
 
-def completed(site, crawl_url):
+def completed_url(site, crawl_url):
     with kombu.Connection(args.amqp_url) as conn:
         q = conn.SimpleQueue("brozzler.sites.{}.completed_urls".format(site.id))
         logging.info("putting {} on queue {}".format(crawl_url, q.queue.name))
         q.put(crawl_url.to_dict())
 
-def brozzle_site(site, chrome_port):
-    with umbra.Browser(chrome_port=chrome_port, chrome_exe=args.chrome_exe,
-            proxy_server=args.proxy_server, ignore_cert_errors=args.ignore_cert_errors) as browser:
-        with browsers_lock:
-            browsers.add(browser)
-        try:
-            while not shutdown_requested.is_set():
+def disclaim_site(site):
+    # XXX maybe should put on "disclaimed" queue and hq should put back on "unclaimed"
+    with kombu.Connection(args.amqp_url) as conn:
+        q = conn.SimpleQueue("brozzler.sites.unclaimed".format(site.id))
+        logging.info("putting {} on queue {}".format(site, q.queue.name))
+        q.put(site.to_dict())
+
+def brozzle_site(site, browser):
+    start = time.time()
+    try:
+        with browser:
+            while not shutdown_requested.is_set() and time.time() - start < 60:
                 try:
                     crawl_url = next_url(site)
                     logging.info("crawling {}".format(crawl_url))
                     crawl_url.outlinks = browser.browse_page(crawl_url.url)
-                    completed(site, crawl_url)
+                    completed_url(site, crawl_url)
                 except kombu.simple.Empty:
                     # if some timeout reached, re-raise?
                     pass
-        # except kombu.simple.Empty:
-        #     logging.info("finished {} (queue is empty)".format(site))
-        except umbra.browser.BrowsingAborted:
-            logging.info("{} shut down")
-        finally:
-            with browsers_lock:
-                browsers.remove(browser)
+    # except kombu.simple.Empty:
+    #     logging.info("finished {} (queue is empty)".format(site))
+    except umbra.browser.BrowsingAborted:
+        logging.info("{} shut down".format(browser))
+    finally:
+        disclaim_site(site)
+        browser_pool.release(browser)
 
 class ShutdownRequested(Exception):
     pass
@@ -91,39 +92,46 @@ def sigint(signum, frame):
 signal.signal(signal.SIGTERM, sigterm)
 signal.signal(signal.SIGINT, sigint)
 
+browser_pool = umbra.browser.BrowserPool(int(args.max_browsers),
+        chrome_exe=args.chrome_exe, proxy_server=args.proxy_server,
+        ignore_cert_errors=args.ignore_cert_errors)
+
 latest_state = None
-chrome_port = 9200
 try:
     while True:
-        if num_browsers < int(args.max_browsers):
-            with kombu.Connection(args.amqp_url) as conn:
-                q = conn.SimpleQueue("brozzler.sites.unclaimed")
+        with kombu.Connection(args.amqp_url) as conn:
+            q = conn.SimpleQueue("brozzler.sites.unclaimed")
+            q_empty = False
+            if len(q) > 0:
                 try:
-                    msg = q.get(block=True, timeout=0.5)
-                    site = hq.Site(**msg.payload)
-                    logging.info("browsing site {}".format(site))
-                    num_browsers += 1
-                    msg.ack()
-                    th = threading.Thread(target=lambda: brozzle_site(site, chrome_port), 
-                            name="BrowsingThread-{}".format(site.scope_surt))
-                    th.start()
-                    chrome_port += 1
-                except kombu.simple.Empty:
-                    if latest_state != "no-unclaimed-sites":
-                        logging.info("no unclaimed sites to browse")
-                        latest_state = "no-unclaimed-sites"
-        else:
-            if latest_state != "browsers-busy":
-                logging.info("all {} browsers are busy, not looking for unclaimed sites".format(args.max_browsers))
-                latest_state = "browsers-busy"
-            time.sleep(0.5)
+                    browser = browser_pool.acquire()
+                    try:
+                        msg = q.get(block=True, timeout=0.5)
+                        site = hq.Site(**msg.payload)
+                        msg.ack()
+                        logging.info("browsing site {}".format(site))
+                        th = threading.Thread(target=lambda: brozzle_site(site, browser), 
+                                name="BrowsingThread-{}".format(site.scope_surt))
+                        th.start()
+                    except kombu.simple.Empty:
+                        q_empty = True
+                except KeyError:
+                    if latest_state != "browsers-busy":
+                        logging.info("all {} browsers are busy".format(args.max_browsers))
+                        latest_state = "browsers-busy"
+            else:
+                q_empty = True
+
+            if q_empty:
+                if latest_state != "no-unclaimed-sites":
+                    logging.info("no unclaimed sites to browse")
+                    latest_state = "no-unclaimed-sites"
+        time.sleep(0.5)
 except ShutdownRequested as e:
     logging.info("shutting down browsers")
     shutdown_requested.set()
 
-    with browsers_lock:
-        for browser in browsers:
-            browser.abort_browse_page()
+    browser_pool.shutdown_now()
 
     for th in threading.enumerate():
         if th != threading.current_thread():
diff --git a/umbra/browser.py b/umbra/browser.py
index d86173d..601387a 100644
--- a/umbra/browser.py
+++ b/umbra/browser.py
@@ -22,12 +22,13 @@ class BrowserPool:
 
     BASE_PORT = 9200
 
-    def __init__(self, size=3, chrome_exe='chromium-browser'):
+    def __init__(self, size=3, **kwargs):
+        """kwargs are passed on to Browser.__init__"""
         self._available = set()
         self._in_use = set()
 
         for i in range(0, size):
-            browser = Browser(BrowserPool.BASE_PORT + i, chrome_exe)
+            browser = Browser(BrowserPool.BASE_PORT + i, **kwargs)
             self._available.add(browser)
 
         self._lock = threading.Lock()