19926: Remove "option 1/2" remnants from the Python SDK install docs

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

diff --git a/sdk/python/arvados/keep.py b/sdk/python/arvados/keep.py
index afb9180e6eb48fe847611ef616cbe34a21b967a9..cbe96ffa2f1c8d038e95f6174b3dc44ec739770a 100644 (file)
--- a/sdk/python/arvados/keep.py
+++ b/sdk/python/arvados/keep.py
@@ -198,14 +198,18 @@ class KeepBlockCache(object):
                 # open it initially and hold the flock(), and a second
                 # hidden one used by mmap().
                 #
-                # Set max slots to 3/8 of maximum file handles.  This
-                # means we'll use at most 3/4 of total file handles.
+                # Set max slots to 1/8 of maximum file handles.  This
+                # means we'll use at most 1/4 of total file handles.
                 #
                 # NOFILE typically defaults to 1024 on Linux so this
-                # is 384 slots (768 file handles), which means we can
-                # cache up to 24 GiB of 64 MiB blocks.  This leaves
-                # 256 file handles for sockets and other stuff.
-                self._max_slots = int((resource.getrlimit(resource.RLIMIT_NOFILE)[0] * 3) / 8)
+                # is 128 slots (256 file handles), which means we can
+                # cache up to 8 GiB of 64 MiB blocks.  This leaves
+                # 768 file handles for sockets and other stuff.
+                #
+                # When we want the ability to have more cache (e.g. in
+                # arv-mount) we'll increase rlimit before calling
+                # this.
+                self._max_slots = int(resource.getrlimit(resource.RLIMIT_NOFILE)[0] / 8)
             else:
                 # RAM cache slots
                 self._max_slots = 512
@@ -335,8 +339,10 @@ class KeepBlockCache(object):
                 self._resize_cache(self.cache_max, self._max_slots-1)
                 while len(self._cache) >= self._max_slots:
                     # If there isn't a slot available, need to wait
-                    # until some other cache action happens.
-                    self._cache_updating.wait()
+                    # for something to happen that releases one of the
+                    # cache slots.  Idle for 200 ms or woken up by
+                    # another thread
+                    self._cache_updating.wait(timeout=0.2)
                     self._resize_cache(self.cache_max, self._max_slots-1)
 
                 if self._disk_cache: