merge from 1.2

CHANGES.txt

@@ -57,6 +57,7 @@
  * Support native link w/o JNA in Java7 (CASSANDRA-3734)
 
 1.2.6
+ * Scale hinted_handoff_throttle_in_kb to cluster size (CASSANDRA-5272)
  * (Hadoop) Fix InputKeyRange in CFIF (CASSANDRA-5536)
  * Fix dealing with ridiculously large max sstable sizes in LCS (CASSANDRA-5589)
  * Ignore pre-truncate hints (CASSANDRA-4655)

NEWS.txt

@@ -66,6 +66,16 @@ Features
       API."
 
 
+1.2.6
+=====
+
+Upgrading
+---------
+    - hinted_handoff_throttle_in_kb is now reduced by a factor
+      proportional to the number of nodes in the cluster (see
+      https://issues.apache.org/jira/browse/CASSANDRA-5272).
+
+
 1.2.5
 =====
 

conf/cassandra.yaml

@@ -42,7 +42,11 @@ hinted_handoff_enabled: true
 # generated.  After it has been dead this long, new hints for it will not be
 # created until it has been seen alive and gone down again.
 max_hint_window_in_ms: 10800000 # 3 hours
-# throttle in KBs per second, per delivery thread
+# Maximum throttle in KBs per second, per delivery thread.  This will be
+# reduced proportionally to the number of nodes in the cluster.  (If there
+# are two nodes in the cluster, each delivery thread will use the maximum
+# rate; if there are three, each will throttle to half of the maximum,
+# since we expect two nodes to be delivering hints simultaneously.)
 hinted_handoff_throttle_in_kb: 1024
 # Number of threads with which to deliver hints;
 # Consider increasing this number when you have multi-dc deployments, since

src/java/org/apache/cassandra/db/HintedHandOffManager.java

@@ -318,7 +318,9 @@ public class HintedHandOffManager implements HintedHandOffManagerMBean
         logger.debug("Using pageSize of {}", pageSize);
 
         // rate limit is in bytes per second. Uses Double.MAX_VALUE if disabled (set to 0 in cassandra.yaml).
-        int throttleInKB = DatabaseDescriptor.getHintedHandoffThrottleInKB();
+        // max rate is scaled by the number of nodes in the cluster (CASSANDRA-5272).
+        int throttleInKB = DatabaseDescriptor.getHintedHandoffThrottleInKB()
+                           / (StorageService.instance.getTokenMetadata().getAllEndpoints().size() - 1);
         RateLimiter rateLimiter = RateLimiter.create(throttleInKB == 0 ? Double.MAX_VALUE : throttleInKB * 1024);
 
         delivery: