Support Questions
Find answers, ask questions, and share your expertise

Slow ReadProcessor warnings leading to application failure

New Contributor

Hello Team,


We are facing Slow ReadProcessor warnings while pulling data from kafka with spark applications. After few slow ReadProcesser warnings, the applications fail. A partial log is attached. Please let us know if you need further information.


Please find below warning message,i am frequently i am seeing this logs and also my application taking too long to complete. 


2021-12-13 03:25:00 WARN DFSClient:854 - Slow ReadProcessor read fields took 117390ms (threshold=30000ms); ack: seqno: 353 reply: SUCCESS reply: SUCCESS reply: SUCCESS downstreamAckTimeNanos: 778712 flag: 0 flag: 0 flag: 0, targets: [DatanodeInfoWithStorage[,DS-ec5cff3e-e958-416e-9ad8-de319cfbc28a,DISK], DatanodeInfoWithStorage[,DS-61163e3d-59ef-4dfc-b194-7385cff86a7c,DISK], DatanodeInfoWithStorage[,DS-af490217-ef46-4d92-bd6e-78bda82c82dc,DISK]]


Thanks & Regards




Couple of possibilities for this WARN messages are:

1) If there is any GC issue on the datanode, this type of WARN messages is seen.

2) If there is any disk issue

3) the last possibility is network latency/slowness between the application, Kafka node, and datanode.

SME || Kafka | Schema Registry | SMM | SRM

Rising Star

I agree @Nandinin's suggestion. Adding some thoughts on hdfs side for your reference:

1. Now you know which 3 DNs maybe slow in the pipeline and the timestamp. So you can go to each datanode log, to see if there are "JvmPauseMonitor" ? or "Lock held"? or other WARN / ERROR ?

2. Refer to this KB, check the Slow message from DN logs around the above timestamp to determine what is the main cause.






@Kallem Has the reply helped resolve your issue? If so, please mark the appropriate reply as the solution, as it will make it easier for others to find the answer in the future. Thanks!


Diana Torres,
Community Moderator

Was your question answered? Make sure to mark the answer as the accepted solution.
If you find a reply useful, say thanks by clicking on the thumbs up button.
Learn more about the Cloudera Community:
; ;