[
https://issues.apache.org/jira/browse/AMQ-6396?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Jason Baik updated AMQ-6396:
----------------------------
Description:
http://activemq.apache.org/nio-transport-reference.html makes it sound as if
the number of threads in the SelectorManager's ThreadPoolExecutor can be capped
with the JVM property:
_org.apache.activemq.transport.nio.SelectorManager.maximumPoolSize_.
{code}
protected ExecutorService createDefaultExecutor() {
ThreadPoolExecutor rc = new
ThreadPoolExecutor(getDefaultCorePoolSize(), getDefaultMaximumPoolSize(),
getDefaultKeepAliveTime(), TimeUnit.SECONDS, new
LinkedBlockingQueue<Runnable>(),
new ThreadFactory() {
private long i = 0;
@Override
public Thread newThread(Runnable runnable) {
Thread t = new Thread(runnable, "ActiveMQ NIO Worker " +
(i++));
t.setDaemon(true);
return t;
}
}, new ThreadPoolExecutor.CallerRunsPolicy());
return rc;
}
{code}
However, this is not true since an unbounded LinkedBlockingQueue is being used
with the the executor. The size of the thread pool will never grow past the
core pool size as per ThreadPoolExecutor's Javadoc:
{quote}
If there are more than corePoolSize but less than maximumPoolSize threads
running, a new thread will be created *only if the queue is full*.
{quote}
I think it's better not to include in the maximumPoolSize property in the
documentation since it can confuse users into thinking that the pool size
should be capped using the maximumPoolSize property, although in reality it's
the corePoolSize property that does that.
Personally this confused me greatly and wasted me a lot of time while
stress-testing the MQTT NIO connector for my company. The broker would
constantly hit a live lock and spawn only 10 threads for the NIO transport,
even if I set the maximumPoolSize to a larger number.
was:
http://activemq.apache.org/nio-transport-reference.html makes it sound as if
the number of threads in the SelectorManager's ThreadPoolExecutor can be capped
with the JVM property:
org.apache.activemq.transport.nio.SelectorManager.maximumPoolSize.
{code}
protected ExecutorService createDefaultExecutor() {
ThreadPoolExecutor rc = new
ThreadPoolExecutor(getDefaultCorePoolSize(), getDefaultMaximumPoolSize(),
getDefaultKeepAliveTime(), TimeUnit.SECONDS, new
LinkedBlockingQueue<Runnable>(),
new ThreadFactory() {
private long i = 0;
@Override
public Thread newThread(Runnable runnable) {
Thread t = new Thread(runnable, "ActiveMQ NIO Worker " +
(i++));
t.setDaemon(true);
return t;
}
}, new ThreadPoolExecutor.CallerRunsPolicy());
return rc;
}
{code}
However, this is not true since an unbounded LinkedBlockingQueue is being used
with the the executor. The size of the thread pool will never grow past the
core pool size as per ThreadPoolExecutor's Javadoc:
{quote}
If there are more than corePoolSize but less than maximumPoolSize threads
running, a new thread will be created *only if the queue is full*.
{quote}
I think it's better not to include in the maximumPoolSize property in the
documentation since it can confuse users into thinking that the pool size
should be capped using the maximumPoolSize property, although in reality it's
the corePoolSize property that does that.
Personally this confused me greatly and wasted me a lot of time while
stress-testing the MQTT NIO connector for my company. The broker would
constantly hit a live lock and spawn only 10 threads for the NIO transport,
even if I set the maximumPoolSize to a larger number.
> JVM property
> org.apache.activemq.transport.nio.SelectorManager.maximumPoolSize has no
> impact
> --------------------------------------------------------------------------------------------
>
> Key: AMQ-6396
> URL: https://issues.apache.org/jira/browse/AMQ-6396
> Project: ActiveMQ
> Issue Type: Improvement
> Components: Transport
> Affects Versions: 5.14.0
> Reporter: Jason Baik
> Priority: Minor
>
> http://activemq.apache.org/nio-transport-reference.html makes it sound as if
> the number of threads in the SelectorManager's ThreadPoolExecutor can be
> capped with the JVM property:
> _org.apache.activemq.transport.nio.SelectorManager.maximumPoolSize_.
> {code}
> protected ExecutorService createDefaultExecutor() {
> ThreadPoolExecutor rc = new
> ThreadPoolExecutor(getDefaultCorePoolSize(), getDefaultMaximumPoolSize(),
> getDefaultKeepAliveTime(), TimeUnit.SECONDS, new
> LinkedBlockingQueue<Runnable>(),
> new ThreadFactory() {
> private long i = 0;
> @Override
> public Thread newThread(Runnable runnable) {
> Thread t = new Thread(runnable, "ActiveMQ NIO Worker " +
> (i++));
> t.setDaemon(true);
> return t;
> }
> }, new ThreadPoolExecutor.CallerRunsPolicy());
> return rc;
> }
> {code}
> However, this is not true since an unbounded LinkedBlockingQueue is being
> used with the the executor. The size of the thread pool will never grow past
> the core pool size as per ThreadPoolExecutor's Javadoc:
> {quote}
> If there are more than corePoolSize but less than maximumPoolSize threads
> running, a new thread will be created *only if the queue is full*.
> {quote}
> I think it's better not to include in the maximumPoolSize property in the
> documentation since it can confuse users into thinking that the pool size
> should be capped using the maximumPoolSize property, although in reality it's
> the corePoolSize property that does that.
> Personally this confused me greatly and wasted me a lot of time while
> stress-testing the MQTT NIO connector for my company. The broker would
> constantly hit a live lock and spawn only 10 threads for the NIO transport,
> even if I set the maximumPoolSize to a larger number.
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