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https://issues.apache.org/jira/browse/CASSANDRA-3494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13161045#comment-13161045
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Peter Schuller commented on CASSANDRA-3494:
-------------------------------------------
We had it set very high. Throttling is not the problem here. The problem is
that each node was sending data to only one bootstrapping node at a time, and
that process was bottlenecking on the destination node's write capacity (see
CASSANDRA-3549 too).
Another effect is that nodes weren't evenly bootstrapping across the cluster;
so some nodes were at 200 gigs whiles other were at 500, because of the
pseudo-random ordering restriction imposed by this limitation (multiple
destinations dogpiling on a source -> some have to just wait for a long time
before they even begin receiving data). In addition to the aggregate bandwidth
limit, this caused even more delay to get to the state where all nodes were
bootstrapped.
> 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.
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