Thanks. But this is something I know. I would like to know will the other TM 
take over the crashed TM's state to ensure data completion(say the state BYKEY, 
different key state will be stored in different TM) OR the crashed TM need to 
be recovered to continue?

For example, 5 records,
rec1:KEYA
rec2:KEYB
rec3:KEYA
rec4:KEYC
rec5:KEYB

TM1 stored state for rec1:KEYA, rec3:KEYA
TM2 stored state for rec2:KEYB, rec5:KEYB <--crashed, what happen to those 
state stored inTM2
TM3 stored state for rec4:KEYC

In case TM2 crashed, rec2 and rec5 will be assigned to other TM? Or those 
record only recover when TM2 being recover?

Thanks.


________________________________
From: Jamie Grier <jgr...@lyft.com>
Sent: Saturday, January 12, 2019 2:26 AM
To: Siew Wai Yow
Cc: user@flink.apache.org
Subject: Re: What happen to state in Flink Task Manager when crash?

Flink is designed such that local state is backed up to a highly available 
system such as HDFS or S3.  When a TaskManager fails state is recovered from 
there.

I suggest reading this:  
https://ci.apache.org/projects/flink/flink-docs-release-1.7/ops/state/state_backends.html


On Fri, Jan 11, 2019 at 7:33 AM Siew Wai Yow 
<wai_...@hotmail.com<mailto:wai_...@hotmail.com>> wrote:
Hello,

May i know what happen to state stored in Flink Task Manager when this Task 
manager crash. Say the state storage is rocksdb, would those data transfer to 
other running Task Manager so that complete state data is ready for data 
processing?

Regards,
Yow

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