diff --git a/b2mirror/mirror.py b/b2mirror/mirror.py
index c47d89e..88015a4 100644
--- a/b2mirror/mirror.py
+++ b/b2mirror/mirror.py
@@ -5,8 +5,15 @@ from urllib.parse import urlparse
 from collections import namedtuple
 from b2.api import B2Api
 import sys
-
+from itertools import islice, filterfalse
 from concurrent.futures import ThreadPoolExecutor, Future
+import logging
+import re
+
+
+#logging.basicConfig(level=logging.INFO)
+
+
 """
 How it works:
 
@@ -21,16 +28,19 @@ Dest will upload the file, and inform the manager it was completed
 """
 class B2SyncManager(object):
 
-    threads = 5
+    workers = 10
 
     def __init__(self, source_module, dest_module):
         self.src = source_module
         self.dest = dest_module
-        self.db = sqlite3.connect('./sync.db')
+        self.db = sqlite3.connect('./sync.db', check_same_thread=False)
         self.db.row_factory = B2SyncManager.dict_factory
         self.db.isolation_level = None # TBD - does it hurt perf?
+        self.exclude_res = [
+            re.compile(r'.*\.(DS_Store|pyc)$')
+        ]
         self._init_db()
-    
+
     @staticmethod
     def dict_factory(cursor, row):
         d = {}
@@ -51,9 +61,10 @@ class B2SyncManager(object):
         tables = {
             "files": """
             CREATE TABLE `files` (
-              `path` varchar(1024),
+              `path` varchar(1024) PRIMARY KEY,
               `mtime` INTEGER,
-              `size` INTEGER
+              `size` INTEGER,
+              `seen` BOOLEAN
             );"""
         }
 
@@ -65,29 +76,63 @@ class B2SyncManager(object):
 
     def sync(self):
         print("Syncing from {} to {}".format(self.src, self.dest))
-        for f in self.src:
-            c = self.db.cursor()
-            
-            row = c.execute("SELECT * FROM 'files' WHERE `path` = ?;", (f.rel_path,)).fetchone()
-            
-            if not row or row['mtime'] < f.mtime:
 
-                print("Uploading: ", f.rel_path, end='')
-                sys.stdout.flush()
+        print(i for i in self.src)
+        chunk_size = 1000
 
+        while True:
+            chunk = list(
+                        filterfalse(  # if rel_path matches any of the REs, the filter is True and the file is skipped
+                            lambda x: any([pattern.match(x.rel_path) for pattern in self.exclude_res]),
+                            islice(self.src, chunk_size)
+                        )
+                    )
+
+            for item in chunk:
+                assert len(item.rel_path) < 512
+
+            if len(chunk) == 0:
+                break
+
+            with ThreadPoolExecutor(max_workers=B2SyncManager.workers) as executor:
+                upload_futures = [executor.submit(self.xfer_file, item) for item in chunk]
+                #print("Queued {} tasks".format(len(chunk)))
+
+            for i in upload_futures:
+                assert i.result()
+
+    def canskip(self, f):
+        if f.rel_path.endswith('.DS_Store'):
+            return True
+        else:
+            return False
+
+    def xfer_file(self, f):
+        c = self.db.cursor()
+
+        row = c.execute("SELECT * FROM 'files' WHERE `path` = ?;", (f.rel_path,)).fetchone()
+
+        if self.canskip(f) or not row or row['mtime'] < f.mtime:
+
+            print("Starting:", f.rel_path)
+            try:
                 self.dest.put_file(f)
-                f.fp.close()
+            except:
+                print("Failed:", f.rel_path)
+                print("Unexpected error:", sys.exc_info()[0])
+                raise
+            #print("Ok: ", f.rel_path)
+            #f.fp.close()
+            # The file was uploaded, commit it to the db
+            c.execute("REPLACE INTO 'files' VALUES(?, ?, ?, ?);", (f.rel_path, f.mtime, f.size, 1))
+            #print("Done: ", f.rel_path)
 
-                print(" ok")
+        else:
+            print("Skipping:", f.rel_path)
 
-                # The file was uploaded, commit it to the db
+        c.close()
 
-                c.execute("INSERT INTO 'files' VALUES(?, ?, ?);", (f.rel_path, f.mtime, f.size,))
-
-            else:
-                print("Skipping: ", f.rel_path)
-
-            c.close()
+        return True
 
 
 class Provider(object):
@@ -97,7 +142,7 @@ class Provider(object):
     def __init__(self):
         pass
 
-FileInfo = namedtuple('FileInfo', ['abs_path', 'rel_path', 'size', 'mtime', 'fp'])
+FileInfo = namedtuple('FileInfo', ['abs_path', 'rel_path', 'size', 'mtime', ]) # 'fp'
 
 class LocalProvider(Provider):
     """
@@ -108,9 +153,9 @@ class LocalProvider(Provider):
         super(LocalProvider, self).__init__()
         self.local_path = local_path
         self.current_set = (None, [], [])
+        self.walker = os.walk(self.local_path)
 
     def __iter__(self):
-        self.walker = os.walk(self.local_path)
         return self
 
     def __next__(self):
@@ -122,7 +167,7 @@ class LocalProvider(Provider):
                 relative_path,
                 os.path.getsize(file_abs_path),
                 int(os.path.getmtime(file_abs_path)),
-                open(file_abs_path, 'rb')
+                #open(file_abs_path, 'rb')
             )
         else:
             self.current_set = self.walker.__next__()
@@ -157,7 +202,7 @@ class B2Reciever(Reciever):
         self.account_id = account_id
         self.app_key = app_key
 
-        self.api = B2Api()
+        self.api = B2Api(max_upload_workers=B2SyncManager.workers)
         self.api.authorize_account('production', self.account_id, self.app_key)
         self.bucket = self.api.get_bucket_by_name(self.bucket)
 
@@ -172,7 +217,7 @@ class B2Reciever(Reciever):
 def sync(source_uri, dest_uri, account_id, app_key):
     source = urlparse(source_uri)
     dest = urlparse(dest_uri)
-    
+
     syncer = B2SyncManager(source_uri, dest_uri)
 
     source_provider = None
@@ -192,6 +237,6 @@ def sync(source_uri, dest_uri, account_id, app_key):
 
     assert source_provider is not None
     assert dest_receiver is not None
-    
+
     syncer = B2SyncManager(source_provider, dest_receiver)
-    syncer.sync()
\ No newline at end of file
+    syncer.sync()