rocketMQTemplate.asyncSend 在 MessageDecoder.messageProperties2String 处抛出 ConcurrentModificationException

Question

I am using rocketmq-spring to send message which version is 2.1.0, sometimes i got ConcurrentModificationException at org.apache.rocketmq.common.message.MessageDecoder.messageProperties2String(MessageDecoder.java:414),the following is a detailed log. Thanks!

 #[xx, 10.xx.52] INFO 2022-05-07 15:31:11.043 [XNIO-1 task-74, 29de7f06241a3313, 29de7f06241a3313] com.xx.common.IpProducerService.asyncSendMessage:45 - contentMap{refNo=xx, system=xx, ip=null, platformId=xx, userId=xxx} #[fp, 10.xx.52] INFO 2022-05-07 15:31:11.043 [XNIO-1 task-74, 29de7f06241a3313, 29de7f06241a3313] com.xx.rocketmq.producer.RocketMqProducer.asyncInfo:19 - -=-=-= [Async Sending Message] -=-=-= Topic = TOPIC_xx_xx Tag = MessageId = null DelayLevel = 0 Content = {"refNo":"xx","system":"xx","platformId":"xx","userId":"xx"} #[fp, 10.xx.52] ERROR 2022-05-07 15:31:11.044 [AsyncSenderExecutor_3, , ] com.xx.rocketmq.producer.ProduceCallBack.onException:32 - asyncSendMessage caused exception. java.util.ConcurrentModificationException: null at java.util.HashMap$HashIterator.nextNode(HashMap.java:1437) at java.util.HashMap$EntryIterator.next(HashMap.java:1471) at java.util.HashMap$EntryIterator.next(HashMap.java:1469) at org.apache.rocketmq.common.message.MessageDecoder.messageProperties2String(MessageDecoder.java:414) at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl.sendKernelImpl(DefaultMQProducerImpl.java:790) at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl.sendDefaultImpl(DefaultMQProducerImpl.java:584) at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl.access$300(DefaultMQProducerImpl.java:97) at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl$4.run(DefaultMQProducerImpl.java:511) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) #[xx, 10.xx.52] INFO 2022-05-07 15:31:11.044 [AsyncSenderExecutor_3, , ] com.xx.common.IpProducerService.handleResult:49 - async produce status is F

Answer 1

use different rocketMQTemplates instance to send same message.

asyncSend is doing on ThreadPool in rocketMQTemplates, there are lots of threads there, so you can't send same message(same message use the same propertiy HashMap, not thread-safe) using different rocketMQTemplates.