# [KB]关于 TiCDC 异常卡住再启动后出现duplicated requests 的问题

## Description

TiCDC 异常 panic ，重启之后导致 TiKV 负载很高，并且出现 log `tikv reported duplicated request to the same region`

## Root Cause

bug 导致 ticdc Panic, 但是重启后 由于 Issue [https://github.com/pingcap/ticdc/issues/2386#issuecomment-938457129](https://github.com/pingcap/ticdc/issues/2386#issuecomment-938457129) 导致 old feed still alive while new feed start working, 所以出现了duplicated request。

修复 PR：[https://github.com/tikv/tikv/pull/10262](https://github.com/tikv/tikv/pull/10262)

## Diagnostic Steps

\[2021/10/05 02:28:15.215 +08:00] \[PANIC] \[client.go:1101] \["tikv reported duplicated request to the same region, which is not expected"] \[regionID=556893] \[stack="[github.com/pingcap/ticdc/cdc/kv.(\*eventFeedSession).handleError\n\tgithub.com/pingcap/ticdc@/cdc/kv/client.go:1101\ngithub.com/pingcap/ticdc/cdc/kv.(\*eventFeedSession).eventFeed.func3\n\tgithub.com/pingcap/ticdc@/cdc/kv/client.go:614\ngolang.org/x/sync/errgroup.(\*Group).Go.func1\n\tgolang.org/x/sync@v0.0.0-20201020160332-67f06af15bc9/errgroup/errgroup.go:57](http://github.com/pingcap/ticdc/cdc/kv.(*eventFeedSession).handleError\n\tgithub.com/pingcap/ticdc@/cdc/kv/client.go:1101\ngithub.com/pingcap/ticdc/cdc/kv.(*eventFeedSession).eventFeed.func3\n\tgithub.com/pingcap/ticdc@/cdc/kv/client.go:614\ngolang.org/x/sync/errgroup.(*Group).Go.func1\n\tgolang.org/x/sync@v0.0.0-20201020160332-67f06af15bc9/errgroup/errgroup.go:57)"]

ticdc log 中有以上 panic 信息

## Resolution

升级至 4.0.16 及以上版本

## Workaround

N/A

## Affect Version(optional)

v4.0.13