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From "Paulo Motta (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-11363) Blocked NTR When Connecting Causing Excessive Load
Date Thu, 07 Apr 2016 19:51:25 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-11363?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15230924#comment-15230924
] 

Paulo Motta commented on CASSANDRA-11363:
-----------------------------------------

I went through 2.1.12 changes and didn't find anything suspicious. On 2.1.13 and 3.0.3 though,
we changed the {{ServerConnection}} query state map from a {{NonBlockingHashMap}} to a {{ConcurrentHashMap}}
on CASSANDRA-10938, which might be misbehaving for some reason.

Is anyone willing to try the revert patch below on 2.1.13 or 3.0.3 and check if that changes
anything?

{noformat}
diff --git a/src/java/org/apache/cassandra/transport/ServerConnection.java b/src/java/org/apache/cassandra/transport/ServerConnection.java
index ce4d164..5991b33 100644
--- a/src/java/org/apache/cassandra/transport/ServerConnection.java
+++ b/src/java/org/apache/cassandra/transport/ServerConnection.java
@@ -17,7 +17,6 @@
  */
 package org.apache.cassandra.transport;
 
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
 import io.netty.channel.Channel;
@@ -29,6 +28,8 @@ import org.apache.cassandra.config.DatabaseDescriptor;
 import org.apache.cassandra.service.ClientState;
 import org.apache.cassandra.service.QueryState;
 
+import org.cliffc.high_scale_lib.NonBlockingHashMap;
+
 public class ServerConnection extends Connection
 {
     private enum State { UNINITIALIZED, AUTHENTICATION, READY }
@@ -37,7 +38,7 @@ public class ServerConnection extends Connection
     private final ClientState clientState;
     private volatile State state;
 
-    private final ConcurrentMap<Integer, QueryState> queryStates = new ConcurrentHashMap<>();
+    private final ConcurrentMap<Integer, QueryState> queryStates = new NonBlockingHashMap<>();
 
     public ServerConnection(Channel channel, int version, Connection.Tracker tracker)
     {
{noformat}

> Blocked NTR When Connecting Causing Excessive Load
> --------------------------------------------------
>
>                 Key: CASSANDRA-11363
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11363
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Coordination
>            Reporter: Russell Bradberry
>            Priority: Critical
>         Attachments: cassandra-102-cms.stack, cassandra-102-g1gc.stack
>
>
> When upgrading from 2.1.9 to 2.1.13, we are witnessing an issue where the machine load
increases to very high levels (> 120 on an 8 core machine) and native transport requests
get blocked in tpstats.
> I was able to reproduce this in both CMS and G1GC as well as on JVM 7 and 8.
> The issue does not seem to affect the nodes running 2.1.9.
> The issue seems to coincide with the number of connections OR the number of total requests
being processed at a given time (as the latter increases with the former in our system)
> Currently there is between 600 and 800 client connections on each machine and each machine
is handling roughly 2000-3000 client requests per second.
> Disabling the binary protocol fixes the issue for this node but isn't a viable option
cluster-wide.
> Here is the output from tpstats:
> {code}
> Pool Name                    Active   Pending      Completed   Blocked  All time blocked
> MutationStage                     0         8        8387821         0              
  0
> ReadStage                         0         0         355860         0              
  0
> RequestResponseStage              0         7        2532457         0              
  0
> ReadRepairStage                   0         0            150         0              
  0
> CounterMutationStage             32       104         897560         0              
  0
> MiscStage                         0         0              0         0              
  0
> HintedHandoff                     0         0             65         0              
  0
> GossipStage                       0         0           2338         0              
  0
> CacheCleanupExecutor              0         0              0         0              
  0
> InternalResponseStage             0         0              0         0              
  0
> CommitLogArchiver                 0         0              0         0              
  0
> CompactionExecutor                2       190            474         0              
  0
> ValidationExecutor                0         0              0         0              
  0
> MigrationStage                    0         0             10         0              
  0
> AntiEntropyStage                  0         0              0         0              
  0
> PendingRangeCalculator            0         0            310         0              
  0
> Sampler                           0         0              0         0              
  0
> MemtableFlushWriter               1        10             94         0              
  0
> MemtablePostFlush                 1        34            257         0              
  0
> MemtableReclaimMemory             0         0             94         0              
  0
> Native-Transport-Requests       128       156         387957        16            278451
> Message type           Dropped
> READ                         0
> RANGE_SLICE                  0
> _TRACE                       0
> MUTATION                     0
> COUNTER_MUTATION             0
> BINARY                       0
> REQUEST_RESPONSE             0
> PAGED_RANGE                  0
> READ_REPAIR                  0
> {code}
> Attached is the jstack output for both CMS and G1GC.
> Flight recordings are here:
> https://s3.amazonaws.com/simple-logs/cassandra-102-cms.jfr
> https://s3.amazonaws.com/simple-logs/cassandra-102-g1gc.jfr
> It is interesting to note that while the flight recording was taking place, the load
on the machine went back to healthy, and when the flight recording finished the load went
back to > 100.



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