cdc: panic after disable syncpoint through cli update

[ben1009]

What did you do?

create changefeed with syncpoint enable
pause
update with syncpoint disable
resume

What did you expect to see?

not panic

What did you see instead?

cdc panic instead

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x2eac771]

goroutine 543 [running]:
github.com/pingcap/tiflow/cdc/owner.(*ddlSinkImpl).emitSyncPoint(0xc0009ae690, 0x41031c8, 0xc000b75650, 0x5fe5c9046dc0000, 0x3093e9c0, 0xed9c4f221)
	github.com/pingcap/tiflow/cdc/owner/ddl_sink.go:205 +0x71
github.com/pingcap/tiflow/cdc/owner.(*changefeed).handleBarrier(0xc002448a20, 0x41031c8, 0xc000b75650, 0x5fe5c9046dc0000, 0x0, 0x0)
	github.com/pingcap/tiflow/cdc/owner/changefeed.go:464 +0x1bc
github.com/pingcap/tiflow/cdc/owner.(*changefeed).tick(0xc002448a20, 0x41031c8, 0xc000b75650, 0xc00249daa0, 0xc001b22b70, 0x2eb20ba, 0xc00335cf30)
	github.com/pingcap/tiflow/cdc/owner/changefeed.go:178 +0x24d
github.com/pingcap/tiflow/cdc/owner.(*changefeed).Tick(0xc002448a20, 0x41030d8, 0xc000b75638, 0xc00249daa0, 0xc001b22b70)
	github.com/pingcap/tiflow/cdc/owner/changefeed.go:117 +0x149
github.com/pingcap/tiflow/cdc/owner.(*Owner).Tick(0xc000613030, 0x7f19e2a75cf0, 0xc000ba08a0, 0x40af638, 0xc000916440, 0x1, 0x0, 0x1, 0x0)
	github.com/pingcap/tiflow/cdc/owner/owner.go:177 +0x36d
github.com/pingcap/tiflow/pkg/orchestrator.(*EtcdWorker).Run(0xc0004b3780, 0x7f19e2a75cf0, 0xc000ba08a0, 0xc001b22900, 0xbebc200, 0x7fff617b0e66, 0x12, 0x0, 0x0)
	github.com/pingcap/tiflow/pkg/orchestrator/etcd_worker.go:239 +0x591
github.com/pingcap/tiflow/cdc/capture.(*Capture).runEtcdWorker(0xc001e20000, 0x4103178, 0xc000ba08a0, 0x40728a0, 0xc000613030, 0x40af638, 0xc000916440, 0xbebc200, 0x0, 0x0)
	github.com/pingcap/tiflow/cdc/capture/capture.go:450 +0x167
github.com/pingcap/tiflow/cdc/capture.(*Capture).campaignOwner(0xc001e20000, 0x4103178, 0xc00063ce40, 0x0, 0x0)
	github.com/pingcap/tiflow/cdc/capture/capture.go:428 +0xa25
github.com/pingcap/tiflow/cdc/capture.(*Capture).run.func2(0xc000f92100, 0xc001e20000, 0x4103178, 0xc00063ce40, 0xc001b800e0)
	github.com/pingcap/tiflow/cdc/capture/capture.go:292 +0xb5
created by github.com/pingcap/tiflow/cdc/capture.(*Capture).run
	github.com/pingcap/tiflow/cdc/capture/capture.go:286 +0x37b

Versions of the cluster

Upstream TiDB cluster version (execute SELECT tidb_version(); in a MySQL client):

5.4

Upstream TiKV version (execute tikv-server --version):

(paste TiKV version here)

TiCDC version (execute cdc version):

5.4

[asddongmen]

This error never appeared again in v5.4.0 and master branch.

[asddongmen]

This problem is cause by we assignment and use ddlSinkImpl.syncPointStore in different goroutine.

Reproducing steps:

• Add a time.Sleep(time.Second * 10) above: https://github.com/pingcap/tiflow/blob/master/cdc/owner/ddl_sink.go#L111
• make cdc
• start cdc server
• create a changefeed with syncpoint enable.
• panic

[MimeLyc]

/remove-label affects-6.2