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Consumer creation API takes longer (results in timeout) #1065

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swapnilgawade16 opened this issue Sep 23, 2022 · 0 comments · May be fixed by #1067
Open

Consumer creation API takes longer (results in timeout) #1065

swapnilgawade16 opened this issue Sep 23, 2022 · 0 comments · May be fixed by #1067

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@swapnilgawade16
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API: https://docs.confluent.io/platform/current/kafka-rest/api.html#consumers
Issue affects approx 5-10 % requests and is evident during high traffic.

Kafka rest version: v7.2.1

Steps to reproduce:

  • Create multple consumers for a group and start calling /records API (keep consuming)
  • There should be active conumers consuming, at this point send a bunch of create new consumer request (100-500 consumer creation).
  • Try above steps multiple times and you should see few consumer creation request will take longer (longer request timerange 20-200 seconds)
@swapnilgawade16 swapnilgawade16 mentioned this issue Sep 23, 2022
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swapnilgawade16 added a commit to swapnilgawade16/kafka-rest that referenced this issue Sep 23, 2022
@swapnilgawade16
fix#1065
dfa1373 
fter few days of experiments found the root cause.

Closes confluentinc#1065

Few details on the fix:
KafkaConsumerManager's "Consumer Expiration Thread" acquires a lock on (KafkaConsumerManager.this instance) and calls expired method of KafkaConsumerState.java. The Consumer Expiration Thread sometimes takes time to get the lock on synchronized expired because there can be a consumer consuming records that has a lock on the KafkaConsumerState instance which may take longer to release depending on the time taken in the IO to fetch the records from kafka broker. The situation can get worse with more number of active consumers fetching records.

The two locks for expired and updateExpiration are not required.

Thread dump snippets
"qtp1551629761-29" prio=5 Id=29 BLOCKED on io.confluent.kafkarest.v2.KafkaConsumerManager@3a09eed4 owned by "Consumer Expiration Thread" Id=47
 at app//io.confluent.kafkarest.v2.KafkaConsumerManager.getConsumerInstance(KafkaConsumerManager.java:669)
 -  blocked on io.confluent.kafkarest.v2.KafkaConsumerManager@3a09eed4 at app//io.confluent.kafkarest.v2.KafkaConsumerManager.getConsumerInstance(KafkaConsumerManager.java:679)

"qtp1551629761-35" prio=5 Id=35 BLOCKED on io.confluent.kafkarest.v2.KafkaConsumerManager@3a09eed4 owned by "Consumer Expiration Thread" Id=47
 at app//io.confluent.kafkarest.v2.KafkaConsumerManager.createConsumer(KafkaConsumerManager.java:180)
 -  blocked on io.confluent.kafkarest.v2.KafkaConsumerManager@3a09eed4 

"Consumer Expiration Thread" daemon prio=5 Id=47 BLOCKED on io.confluent.kafkarest.v2.JsonKafkaConsumerState@4d2bbeda owned by "pool-4-thread-13" Id=153
 at app//io.confluent.kafkarest.v2.KafkaConsumerState.expired(KafkaConsumerState.java:345)
 -  blocked on io.confluent.kafkarest.v2.JsonKafkaConsumerState@4d2bbeda at app//io.confluent.kafkarest.v2.KafkaConsumerManager$ExpirationThread.run(KafkaConsumerManager.java:761)
 -  locked io.confluent.kafkarest.v2.KafkaConsumerManager@3a09eed4

"pool-4-thread-13" prio=5 Id=153 RUNNABLE (in native)
 at [email protected]/sun.nio.ch.EPoll.wait(Native Method)
 at [email protected]/sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:120)
 at [email protected]/sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:124)
 -  locked sun.nio.ch.Util$2@1458190c
 -  locked sun.nio.ch.EPollSelectorImpl@3ebca1e6
 at [email protected]/sun.nio.ch.SelectorImpl.select(SelectorImpl.java:136)
 at app//org.apache.kafka.common.network.Selector.select(Selector.java:869)
 at app//org.apache.kafka.common.network.Selector.poll(Selector.java:465)
 at app//org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:561)
 at app//org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:265)
@swapnilgawade16 swapnilgawade16 linked a pull request Sep 23, 2022 that will close this issue
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fix#1065 swapnilgawade16/kafka-rest
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