18941: bugfixing prefetch

[arvados.git] / sdk / python / arvados / arvfile.py

diff --git a/sdk/python/arvados/arvfile.py b/sdk/python/arvados/arvfile.py
index 0fcdc1e6334957f27a5ff1f10fbdedcf2716609a..b21ebd331769109ca0cca3b23e2c45f17ed2c9ed 100644 (file)
--- a/sdk/python/arvados/arvfile.py
+++ b/sdk/python/arvados/arvfile.py
@@ -479,7 +479,7 @@ class _BlockManager(object):
     """
 
     DEFAULT_PUT_THREADS = 2
-    DEFAULT_GET_THREADS = 2
+    DEFAULT_GET_THREADS = 4
 
     def __init__(self, keep, copies=None, put_threads=None, num_retries=None, storage_classes_func=None):
         """keep: KeepClient object to use"""
@@ -593,6 +593,9 @@ class _BlockManager(object):
                 b = self._prefetch_queue.get()
                 if b is None:
                     return
+                if self._keep.has_cache_slot(b):
+                    continue
+                _logger.debug("prefetching %s", b)
                 self._keep.get(b)
             except Exception:
                 _logger.exception("Exception doing block prefetch")
@@ -841,7 +844,7 @@ class _BlockManager(object):
         if not self.prefetch_enabled:
             return
 
-        if self._keep.get_from_cache(locator) is not None:
+        if self._keep.has_cache_slot(locator):
             return
 
         with self.lock:
@@ -849,6 +852,7 @@ class _BlockManager(object):
                 return
 
         self.start_get_threads()
+        # _logger.debug("pushing %s to prefetch", locator)
         self._prefetch_queue.put(locator)
 
 
@@ -1099,7 +1103,7 @@ class ArvadosFile(object):
             if size == 0 or offset >= self.size():
                 return b''
             readsegs = locators_and_ranges(self._segments, offset, size)
-            prefetch = locators_and_ranges(self._segments, offset + size, config.KEEP_BLOCK_SIZE, limit=32)
+            prefetch = locators_and_ranges(self._segments, offset + size, config.KEEP_BLOCK_SIZE*4, limit=32)
 
         locs = set()
         data = []
@@ -1117,7 +1121,10 @@ class ArvadosFile(object):
                 self.parent._my_block_manager().block_prefetch(lr.locator)
                 locs.add(lr.locator)
 
-        return b''.join(data)
+        if len(data) == 1:
+            return data[0]
+        else:
+            return b''.join(data)
 
     @must_be_writable
     @synchronized