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Christian Esken edited comment on CASSANDRA-13265 at 3/13/17 1:56 PM: ---------------------------------------------------------------------- The change is now finished, including configuration, MBean and testing. I also tested an interval of 0 ms, which is close to what Cassandra does today. Please have a look. What is the recommended way of getting this into the official Cassandra repo? A patch, or would someone with write access take it directly from Github? This also has impact on how the merge conflicts will be resolved, as there are now 3 files merge conflicts according to https://github.com/apache/cassandra/pull/95. I did not want to rebase my branch without asking. was (Author: cesken): The change is now finished, including configuration, MBean and testing. I also tested an interval of 0 ms, which is close to what Cassandra does today. Please have a look. What is the recommended way of getting this into the official Cassandra repo? A patch, or would someone with write access take it directly from Github? This also has impact on how the merge conflicts will be resolved, as there are now 3 files with conflicts e branch has now merge conflicts on 3 files according to https://github.com/apache/cassandra/pull/95. I did not want to rebase my branch without asking. > Expiration in OutboundTcpConnection can block the reader Thread > --------------------------------------------------------------- > > Key: CASSANDRA-13265 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13265 > Project: Cassandra > Issue Type: Bug > Environment: Cassandra 3.0.9 > Java HotSpot(TM) 64-Bit Server VM version 25.112-b15 (Java version > 1.8.0_112-b15) > Linux 3.16 > Reporter: Christian Esken > Assignee: Christian Esken > Attachments: cassandra.pb-cache4-dus.2017-02-17-19-36-26.chist.xz, > cassandra.pb-cache4-dus.2017-02-17-19-36-26.td.xz > > > I observed that sometimes a single node in a Cassandra cluster fails to > communicate to the other nodes. This can happen at any time, during peak load > or low load. Restarting that single node from the cluster fixes the issue. > Before going in to details, I want to state that I have analyzed the > situation and am already developing a possible fix. Here is the analysis so > far: > - A Threaddump in this situation showed 324 Threads in the > OutboundTcpConnection class that want to lock the backlog queue for doing > expiration. > - A class histogram shows 262508 instances of > OutboundTcpConnection$QueuedMessage. > What is the effect of it? As soon as the Cassandra node has reached a certain > amount of queued messages, it starts thrashing itself to death. Each of the > Thread fully locks the Queue for reading and writing by calling > iterator.next(), making the situation worse and worse. > - Writing: Only after 262508 locking operation it can progress with actually > writing to the Queue. > - Reading: Is also blocked, as 324 Threads try to do iterator.next(), and > fully lock the Queue > This means: Writing blocks the Queue for reading, and readers might even be > starved which makes the situation even worse. > ----- > The setup is: > - 3-node cluster > - replication factor 2 > - Consistency LOCAL_ONE > - No remote DC's > - high write throughput (100000 INSERT statements per second and more during > peak times). > -- This message was sent by Atlassian JIRA (v6.3.15#6346)