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From jbel...@apache.org
Subject [9/14] git commit: add warning to multithreaded_compaction
Date Tue, 11 Dec 2012 18:38:28 GMT
add warning to multithreaded_compaction


Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo
Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/ca02176f
Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/ca02176f
Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/ca02176f

Branch: refs/heads/cassandra-1.2.0
Commit: ca02176fc0cde6eee6b0f278ece58ce8ce202d18
Parents: 36b183f
Author: Jonathan Ellis <jbellis@apache.org>
Authored: Tue Dec 11 12:37:47 2012 -0600
Committer: Jonathan Ellis <jbellis@apache.org>
Committed: Tue Dec 11 12:37:47 2012 -0600

----------------------------------------------------------------------
 conf/cassandra.yaml |   15 +++++++++------
 1 files changed, 9 insertions(+), 6 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/cassandra/blob/ca02176f/conf/cassandra.yaml
----------------------------------------------------------------------
diff --git a/conf/cassandra.yaml b/conf/cassandra.yaml
index c4732db..543ad65 100644
--- a/conf/cassandra.yaml
+++ b/conf/cassandra.yaml
@@ -381,12 +381,15 @@ in_memory_compaction_limit_in_mb: 64
 # Uncomment to make compaction mono-threaded, the pre-0.8 default.
 #concurrent_compactors: 1
 
-# Multi-threaded compaction. When enabled, each compaction will use
-# up to one thread per core, plus one thread per sstable being merged.
-# This is usually only useful for SSD-based hardware: otherwise, 
-# your concern is usually to get compaction to do LESS i/o (see:
-# compaction_throughput_mb_per_sec), not more.
-multithreaded_compaction: false
+# multithreaded_compaction: false. When enabled, each compaction will
+# use up to one thread per core, plus one thread per sstable being
+# merged.  This is usually only useful for SSD-based hardware:
+# otherwise, your concern is usually to get compaction to do LESS i/o
+# (see: compaction_throughput_mb_per_sec), not more.
+#
+# WARNING: this setting has caused compaction deadlocks for multiple
+# users (see CASSANDRA-4492).  It is recommended to leave this off
+# unless you are prepared to help troubleshoot.
 
 # Throttles compaction to the given total throughput across the entire
 # system. The faster you insert data, the faster you need to compact in


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