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Posted to commits@hbase.apache.org by st...@apache.org on 2014/08/18 23:13:48 UTC
[2/3] git commit: edit on why bucketcache
edit on why bucketcache
Project: http://git-wip-us.apache.org/repos/asf/hbase/repo
Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/1f1a676c
Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/1f1a676c
Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/1f1a676c
Branch: refs/heads/master
Commit: 1f1a676cfe5e132523b6bb9ac4a1f319b24656ff
Parents: ef70ce8
Author: stack <st...@apache.org>
Authored: Fri Aug 8 11:22:47 2014 -0700
Committer: stack <st...@apache.org>
Committed: Mon Aug 18 14:13:33 2014 -0700
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src/main/docbkx/book.xml | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
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http://git-wip-us.apache.org/repos/asf/hbase/blob/1f1a676c/src/main/docbkx/book.xml
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diff --git a/src/main/docbkx/book.xml b/src/main/docbkx/book.xml
index 11b356b..dbf9029 100644
--- a/src/main/docbkx/book.xml
+++ b/src/main/docbkx/book.xml
@@ -2113,9 +2113,11 @@ rs.close();
</para>
<para>Fetching will always be slower when fetching from BucketCache,
- as compared with the native onheap LruBlockCache. However, latencies tend to be
- less erratic across time, because there is less garbage collection. This is why
- you'd use BucketCache, so your latencies are less erratic and to mitigate GCs
+ as compared to the native onheap LruBlockCache. However, latencies tend to be
+ less erratic across time, because there is less garbage collection when you use
+ BucketCache since it is managing BlockCache allocations, not the GC. If the
+ BucketCache is deployed in offheap mode, this memory is not managed by the
+ GC at all. This is why you'd use BucketCache, so your latencies are less erratic and to mitigate GCs
and heap fragmentation. See Nick Dimiduk's <link
xlink:href="http://www.n10k.com/blog/blockcache-101/">BlockCache 101</link> for
comparisons running onheap vs offheap tests. Also see