[
https://issues.apache.org/jira/browse/CASSANDRA-3494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13161051#comment-13161051
]
Peter Schuller commented on CASSANDRA-3494:
-------------------------------------------
(Part of the reason the destinations were bottlenecking were that the sstable
rebuilds + minor compactions happening during streaming are expensive and eat
disk throughput. So you'd have a bunch of machines just idling waiting for the
sender to send them some data, while the sender is blocking on a write to a TCP
conenction, where on the other end some receiver is blocking on a write to disk
because that node happened to be lucky and got some good sources and got more
streams to it than it could handle in terms of throughput.)
> Streaming is mono-threaded (the bulk loader too by extension)
> -------------------------------------------------------------
>
> Key: CASSANDRA-3494
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3494
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 0.8.0
> Reporter: Sylvain Lebresne
> Priority: Minor
>
> The streamExecutor is define as:
> {noformat}
> streamExecutor_ = new DebuggableThreadPoolExecutor("Streaming",
> Thread.MIN_PRIORITY);
> {noformat}
> In the meantime, in DebuggableThreadPoolExecutor.java:
> {noformat}
> public DebuggableThreadPoolExecutor(String threadPoolName, int priority)
> {
> this(1, Integer.MAX_VALUE, TimeUnit.SECONDS, new
> LinkedBlockingQueue<Runnable>(), new NamedThreadFactory(threadPoolName,
> priority));
> }
> {noformat}
> In other word, since the core pool size is 1 and the queue unbounded, tasks
> will always queued and the executor is essentially mono-threaded.
> This is clearly not necessary since we already have stream throttling
> nowadays. And it could be a limiting factor in the case of the bulk loader.
> Besides, I would venture that this maybe was not the intention, because
> putting the max core size to MAX_VALUE would suggest that the intention was
> to spawn threads on demand.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
