MySQL server has gone away when use mysql client to connect TiDB server.

[blacktear23]

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

Connect to TiDB use mysql command line tool, then use database and execute show tables;

2. What did you expect to see?

List tables.

3. What did you see instead?

ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...

And tidb.log contains stack trace:

2017/10/23 11:47:02.948 server.go:138: [info] [5980] new connection 10.55.0.1:50338
2017/10/23 11:47:02.960 conn.go:388: [error] lastCmd bigdata_company_domain_map, runtime error: index out of range, goroutine 9019713 [running]:
github.com/pingcap/tidb/server.(*clientConn).Run.func1(0xc425e43ad0)
	/build/src/github.com/pingcap/tidb/server/conn.go:386 +0xfd
panic(0x1056740, 0x1a82680)
	/usr/local/go/src/runtime/panic.go:489 +0x2cf
github.com/pingcap/tidb/plan.(*DataSource).getStatsProfileByFilter(0xc42015f380, 0x0, 0x0, 0x0, 0x1)
	/build/src/github.com/pingcap/tidb/plan/stats.go:78 +0x325
github.com/pingcap/tidb/plan.(*DataSource).prepareStatsProfile(0xc42015f380, 0x18c6060)
	/build/src/github.com/pingcap/tidb/plan/stats.go:93 +0x53
github.com/pingcap/tidb/plan.(*Limit).prepareStatsProfile(0xc422458d70, 0x18c65a0)
	/build/src/github.com/pingcap/tidb/plan/stats.go:118 +0x72
github.com/pingcap/tidb/plan.(*Projection).prepareStatsProfile(0xc422458c80, 0x0)
	/build/src/github.com/pingcap/tidb/plan/stats.go:172 +0x83
github.com/pingcap/tidb/plan.dagPhysicalOptimize(0x18cbce0, 0xc422458c80, 0xc422458c01, 0x18b2c40, 0xc462159e00, 0xc42a68ff48)
	/build/src/github.com/pingcap/tidb/plan/optimizer.go:150 +0x4f
github.com/pingcap/tidb/plan.doOptimize(0x43, 0x18cbce0, 0xc422458c80, 0x18b2c40, 0xc462159e00, 0xc42a68ff48, 0x1, 0xc4202ab6c0, 0xc455b13800, 0xd26539)
	/build/src/github.com/pingcap/tidb/plan/optimizer.go:120 +0xdd
github.com/pingcap/tidb/plan.Optimize(0x18b2c40, 0xc462159e00, 0x18a7a20, 0xc45c6cf220, 0x7fb8a3be8d68, 0xc4215c0c00, 0x0, 0x0, 0x1, 0xc4225744e0)
	/build/src/github.com/pingcap/tidb/plan/optimizer.go:81 +0x223
github.com/pingcap/tidb/executor.(*Compiler).Compile(0xc455b13923, 0x18b2c40, 0xc462159e00, 0x18ab4e0, 0xc45c6cf220, 0x11dfa60, 0xf, 0xc4ba795b80)
	/build/src/github.com/pingcap/tidb/executor/compiler.go:40 +0x1ae
github.com/pingcap/tidb.(*session).Execute(0xc462159e00, 0xc421346c80, 0x32, 0x0, 0x3, 0xc421346c80, 0xc421346ca9, 0xc455b13bb0)
	/build/src/github.com/pingcap/tidb/session.go:724 +0x891
github.com/pingcap/tidb/server.(*TiDBContext).Execute(0xc44ee90c60, 0xc421346c80, 0x32, 0xc4202aae41, 0x1a, 0x11d70a4, 0x9, 0xc421346c80)
	/build/src/github.com/pingcap/tidb/server/driver_tidb.go:194 +0x62
github.com/pingcap/tidb/server.(*TiDBContext).FieldList(0xc44ee90c60, 0xc4202aae41, 0x1a, 0x1, 0xc4202aae80, 0x2, 0x2, 0xc421876418)
	/build/src/github.com/pingcap/tidb/server/driver_tidb.go:233 +0x8e
github.com/pingcap/tidb/server.(*clientConn).handleFieldList(0xc425e43ad0, 0xc4202aae41, 0x1b, 0x1aeec50, 0x1c)
	/build/src/github.com/pingcap/tidb/server/conn.go:758 +0xa6
github.com/pingcap/tidb/server.(*clientConn).dispatch(0xc425e43ad0, 0xc4202aae41, 0x1c, 0x1b, 0x0, 0x0)
	/build/src/github.com/pingcap/tidb/server/conn.go:528 +0x52f
github.com/pingcap/tidb/server.(*clientConn).Run(0xc425e43ad0)
	/build/src/github.com/pingcap/tidb/server/conn.go:409 +0x13c
github.com/pingcap/tidb/server.(*Server).onConn(0xc421876480, 0x18b0ac0, 0xc4213cc9a8)
	/build/src/github.com/pingcap/tidb/server/server.go:334 +0x18e
created by github.com/pingcap/tidb/server.(*Server).Run
	/build/src/github.com/pingcap/tidb/server/server.go:273 +0xc8

2017/10/23 11:47:02.960 server.go:309: [info] [5980] close connection

4. What version of TiDB are you using (tidb-server -V)?

TiDB version is 1.0.0

[blacktear23]

Follow the stack trace, found error code should be here:

[shenli]

@blacktear23 Thanks for your feedback! May I have your GitHash? You can get it by select tidb_version();.

[shenli]

@hanfei1991 @lamxTyler PTAL

[blacktear23]

@shenli you can trace my fork's spcmaster branch. This is build by this branch. https://github.com/blacktear23/tidb/tree/spcmaster

[blacktear23]

@shenli PR #4864 seems fix my production cluster.

[alivxxx]

@blacktear23 Seems that this problem is already fixed by #4825 , could you try it?

[blacktear23]

@lamxTyler what about current data? Seems this PR only fix for insert on stat build. If I already have a built data in database, seems this problem should be reproduced.

[alivxxx]

@blacktear23 Yes, you are right.

[blacktear23]

PR #4864 is merged so close this issue.