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https://issues.apache.org/jira/browse/CASSANDRA-13265?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15904949#comment-15904949
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Christian Esken edited comment on CASSANDRA-13265 at 3/10/17 11:45 AM:
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I am nearly done with the configuration, and have two questions about it:
1. How to handle the default value? My approach is to pre-configure the
default value in Config:
{code}
public static final int otc_backlog_expiration_interval_in_ms_default = 200;
public volatile Integer otc_backlog_expiration_interval_in_ms =
otc_backlog_expiration_interval_in_ms_default;
{code}
Additionally I will handle null values, that might come in via MBean in the
getter of DatabaseDescriptor:
{code}
public static Integer getOtcBacklogExpirationInterval()
{
Integer confValue = conf.otc_backlog_expiration_interval_in_ms;
return confValue != null ? confValue :
Config.otc_backlog_expiration_interval_in_ms_default;
}
{code}
2. How to read the config value? I am seeing some Integer.getInteger(propName,
defaultValue), but this looks strange to me. I think changes from JMX would not
even be reflected. Thus I am calling the getter from above:
{{DatabaseDescriptor.getOtcBacklogExpirationInterval()}}. Is thte latter OK?
was (Author: cesken):
I am nearly done with the configuration, and have two questions about it:
1. How to handle the default value? My approach is to pre-configure the
default value in Config:
{code}
public static final int otc_backlog_expiration_interval_in_ms_default = 200;
public volatile Integer otc_backlog_expiration_interval_in_ms =
otc_backlog_expiration_interval_in_ms_default;
{code}
- Additionally I will handle null values, that might come in via MBean in the
getter of DatabaseDescriptor:
{code}
public static Integer getOtcBacklogExpirationInterval()
{
Integer confValue = conf.otc_backlog_expiration_interval_in_ms;
return confValue != null ? confValue :
Config.otc_backlog_expiration_interval_in_ms_default;
}
{code}
2. How to read the config value? I am seeing some Integer.getInteger(propName,
defaultValue), but this looks strange to me. I think changes from JMX would not
even be reflected. Thus I am calling the getter from above:
{{DatabaseDescriptor.getOtcBacklogExpirationInterval()}}. Is thte latter OK?
> 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).
>
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