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https://issues.apache.org/jira/browse/KAFKA-10134?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17156214#comment-17156214
]
Jerry Wei commented on KAFKA-10134:
-----------------------------------
[~guozhang], I have three brokers and 10 consumers. When I restart one of
consumers, some of other consumers will be with high CPU issue.
{code:java}
// from KafkaConsumer.java (a fine fix)
// private ConsumerRecords<K, V> poll(final Timer timer, final boolean
includeMetadataInTimeout);
if (includeMetadataInTimeout) {
// try to update assignment metadata BUT do not need to
block on the timer if we still have
// some assigned partitions, since even if we are 1) in the
middle of a rebalance
// or 2) have partitions with unknown starting positions we
may still want to return some data
// as long as there are some partitions fetchable; NOTE we
always use a timer with 0ms
// to never block on completing the rebalance procedure if
there's any
if (subscriptions.fetchablePartitions(tp ->
true).isEmpty()) {
updateAssignmentMetadataIfNeeded(timer);
} else {
final Timer updateMetadataTimer = time.timer(0L);
updateAssignmentMetadataIfNeeded(updateMetadataTimer);
timer.update(updateMetadataTimer.currentTimeMs());
}
} else {
while
(!updateAssignmentMetadataIfNeeded(time.timer(Long.MAX_VALUE))) {
log.warn("Still waiting for metadata");
}
}
{code}
{code:java}
// from KafkaConsumer.java (last commit)
// private ConsumerRecords<K, V> poll(final Timer timer, final boolean
includeMetadataInTimeout);
if (includeMetadataInTimeout) {
// try to update assignment metadata BUT do not need to
block on the timer for join group
updateAssignmentMetadataIfNeeded(timer, false);
} else {
while
(!updateAssignmentMetadataIfNeeded(time.timer(Long.MAX_VALUE), true)) {
log.warn("Still waiting for metadata");
}
}
{code}
Per the above two commits I have one question about
`updateAssignmentMetadataIfNeeded(timer, false);` why the second parameter is
false? Per my understanding when it's false, actually it's same as before
`updateAssignmentMetadataIfNeeded(time.timer(0L));`
I've tested w/ true, it looks fine for us and I'm thinking when it's w/ true,
the behavior is similar to [ the
commit|https://github.com/apache/kafka/pull/8934/commits/333a967ec22ea22babf32b18349b76b6552a2fac].
> High CPU issue during rebalance in Kafka consumer after upgrading to 2.5
> ------------------------------------------------------------------------
>
> Key: KAFKA-10134
> URL: https://issues.apache.org/jira/browse/KAFKA-10134
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Affects Versions: 2.5.0
> Reporter: Sean Guo
> Assignee: Guozhang Wang
> Priority: Blocker
> Fix For: 2.6.0, 2.5.1
>
>
> We want to utilize the new rebalance protocol to mitigate the stop-the-world
> effect during the rebalance as our tasks are long running task.
> But after the upgrade when we try to kill an instance to let rebalance happen
> when there is some load(some are long running tasks >30S) there, the CPU will
> go sky-high. It reads ~700% in our metrics so there should be several threads
> are in a tight loop. We have several consumer threads consuming from
> different partitions during the rebalance. This is reproducible in both the
> new CooperativeStickyAssignor and old eager rebalance rebalance protocol. The
> difference is that with old eager rebalance rebalance protocol used the high
> CPU usage will dropped after the rebalance done. But when using cooperative
> one, it seems the consumers threads are stuck on something and couldn't
> finish the rebalance so the high CPU usage won't drop until we stopped our
> load. Also a small load without long running task also won't cause continuous
> high CPU usage as the rebalance can finish in that case.
>
> "executor.kafka-consumer-executor-4" #124 daemon prio=5 os_prio=0
> cpu=76853.07ms elapsed=841.16s tid=0x00007fe11f044000 nid=0x1f4 runnable
> [0x00007fe119aab000]"executor.kafka-consumer-executor-4" #124 daemon prio=5
> os_prio=0 cpu=76853.07ms elapsed=841.16s tid=0x00007fe11f044000 nid=0x1f4
> runnable [0x00007fe119aab000] java.lang.Thread.State: RUNNABLE at
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator.poll(ConsumerCoordinator.java:467)
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.updateAssignmentMetadataIfNeeded(KafkaConsumer.java:1275)
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1241)
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1216)
> at
>
> By debugging into the code we found it looks like the clients are in a loop
> on finding the coordinator.
> I also tried the old rebalance protocol for the new version the issue still
> exists but the CPU will be back to normal when the rebalance is done.
> Also tried the same on the 2.4.1 which seems don't have this issue. So it
> seems related something changed between 2.4.1 and 2.5.0.
>
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