Josh Byster created ARTEMIS-4575:
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Summary: Don't start all previous consumers when new consumer added
Key: ARTEMIS-4575
URL: https://issues.apache.org/jira/browse/ARTEMIS-4575
Project: ActiveMQ Artemis
Issue Type: Improvement
Reporter: Josh Byster
I was running a benchmark to add many consumers, and I see that the marginal
cost of adding a new consumer increases due to a linear-time iteration through
all the existing consumers with OpenWire. It becomes very slow to add a new
consumer when there are already 100k+ on a session, for example. We have
thousands of topics and we see a huge performance slowdown due to this.
More specifically, the stack trace:
{code:java}
org.apache.activemq.artemis.utils.ActiveMQThreadFactory$1.run(ActiveMQThreadFactory.java:118)
java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
org.apache.activemq.artemis.utils.actors.ProcessorBase.executePendingTasks(ProcessorBase.java:68)
org.apache.activemq.artemis.utils.actors.OrderedExecutor.doTask(OrderedExecutor.java:32)
org.apache.activemq.artemis.utils.actors.OrderedExecutor.doTask(OrderedExecutor.java:57)
org.apache.activemq.artemis.utils.actors.ProcessorBase.executePendingTasks(ProcessorBase.java:68)
org.apache.activemq.artemis.utils.actors.ThresholdActor.doTask(ThresholdActor.java:73)
org.apache.activemq.artemis.core.protocol.openwire.OpenWireConnection.act(OpenWireConnection.java:369)
org.apache.activemq.command.ConsumerInfo.visit(ConsumerInfo.java:352)
org.apache.activemq.artemis.core.protocol.openwire.OpenWireConnection$CommandProcessor.processAddConsumer(OpenWireConnection.java:1280)
org.apache.activemq.artemis.core.protocol.openwire.OpenWireConnection.addConsumer(OpenWireConnection.java:1001)
org.apache.activemq.artemis.core.protocol.openwire.amq.AMQSession.start(AMQSession.java:257)
org.apache.activemq.artemis.core.server.impl.ServerSessionImpl.start(ServerSessionImpl.java:1699)
org.apache.activemq.artemis.core.server.impl.ServerSessionImpl.setStarted(ServerSessionImpl.java:2166)
{code}
{{Most of the time is spent in this method, starting consumers that have
previously been started:}}
{code:java}
private void setStarted(final boolean s) {
Set<ServerConsumer> consumersClone = new HashSet<>(consumers.values());
for (ServerConsumer consumer : consumersClone) {
consumer.setStarted(s);
}
started = s;
} {code}
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