Try to improve tikv_client_read_timeout retry logic when 1 tikv server down

[crazycs520]

Related log are following:

• tikv_client_read_timeout = 100
• max_execution_time = 400

[2024/04/22 17:32:40.752 +08:00] [INFO] [region_request.go:1804] ["throwing pseudo region error due to no replica available"] [conn=3787456712] [session_alias=] [req-ts=449256713093120000] [req-type=Cop] [region="{ region id: 290313, ver: 498, confVer: 209 }"] [replica-read-type=mixed] [stale-read=false] [request-sender="{rpcError:[192.168.80.3:23360](1) wait recvLoop timeout,timeout:100ms, wait_duration:4.499µs:: context deadline exceeded, replicaSelector: replicaSelectorV2{replicaReadType: mixed, attempts: 5, cacheRegionIsValid: true, replicaStatus: [peer: 298850, store: 4, isEpochStale: false, attempts: 2, replica-epoch: 0, store-epoch: 0, store-state: resolved, store-liveness-state: reachable peer: 298992, store: 10, isEpochStale: false, attempts: 1, replica-epoch: 0, store-epoch: 0, store-state: resolved, store-liveness-state: reachable peer: 333879, store: 2, isEpochStale: false, attempts: 1, replica-epoch: 0, store-epoch: 0, store-state: resolved, store-liveness-state: reachable]}}"] [retry-times=4] [total-backoff-ms=2] [total-backoff-times=1] [max-exec-timeout-ms=100] [stats="Cop:{num_rpc:4, total_time:302.3ms}, rpc_errors:{data_is_not_ready:1, context deadline exceeded:3}"] [access-path="{stale_read, peer:298850, store:4, err:data_is_not_ready}, {peer:333879, store:2, err:context deadline exceeded}, {replica_read, peer:298850, store:4, err:context deadline exceeded}, {replica_read, peer:298992, store:10, err:context deadline exceeded}"] [cost=304.411625ms]
[2024/04/22 17:32:40.752 +08:00] [INFO] [coprocessor.go:1384] ["[TIME_COP_PROCESS] resp_time:304.488311ms txnStartTS:449256713093120000 region_id:290313 store_addr:192.168.80.3:23360 stats:Cop:{num_rpc:4, total_time:302.3ms}, rpc_errors:{data_is_not_ready:1, context deadline exceeded:3} region_err:epoch_not_match:<> "] [conn=3787456712] [session_alias=]
[2024/04/22 17:32:40.946 +08:00] [INFO] [region_request.go:1804] ["send request failed, err: context canceled"] [conn=3787456712] [session_alias=] [req-ts=449256713093120000] [req-type=Cop] [region="{ region id: 290313, ver: 498, confVer: 209 }"] [replica-read-type=mixed] [stale-read=false] [request-sender="{rpcError:[192.168.80.4:23360](1) context canceled, replicaSelector: replicaSelectorV2{replicaReadType: mixed, attempts: 2, cacheRegionIsValid: true, replicaStatus: [peer: 298850, store: 4, isEpochStale: false, attempts: 1, replica-epoch: 0, store-epoch: 0, store-state: resolved, store-liveness-state: reachable peer: 298992, store: 10, isEpochStale: false, attempts: 0, replica-epoch: 0, store-epoch: 0, store-state: resolved, store-liveness-state: reachable peer: 333879, store: 2, isEpochStale: false, attempts: 1, replica-epoch: 0, store-epoch: 0, store-state: resolved, store-liveness-state: reachable]}}"] [retry-times=1] [total-backoff-ms=8] [total-backoff-times=3] [max-exec-timeout-ms=60000] [stats="Cop:{num_rpc:6, total_time:490.2ms}, rpc_errors:{data_is_not_ready:2, context deadline exceeded:3, context canceled:1}"] [access-path="{stale_read, peer:298850, store:4, err:data_is_not_ready}, {peer:333879, store:2, err:context canceled}"] [cost=192.074631ms]
[2024/04/22 17:32:40.947 +08:00] [INFO] [conn.go:1151] ["command dispatched failed"] [conn=3787456712] [session_alias=] [connInfo="id:3787456712, addr:192.168.80.1:48834 status:10, collation:latin1_swedish_ci, user:root"] [command=Query] [status="inTxn:0, autocommit:1"] [sql="select pk, sk, ts, v, n from (             select pk, sk, ts, v, row_number() over (partition by pk, sk order by ts desc) as n             from t1 as of timestamp now() - interval 5 second where pk = '000000000000000000000000399911' and sk like '0000-0001-0002-0004-0008%'         ) as tt where n <= 4 order by sk asc"] [txn_mode=PESSIMISTIC] [timestamp=449256713093120000] [err="[executor:3024]Query execution was interrupted, maximum statement execution time exceeded\ngithub.com/pingcap/errors.AddStack\n\t/data/cs/code/pkg/mod/github.com/pingcap/[email protected]/errors.go:178\ngithub.com/pingcap/errors.(*Error).GenWithStackByArgs\n\t/data/cs/code/pkg/mod/github.com/pingcap/[email protected]/normalize.go:175\ngithub.com/pingcap/tidb/pkg/util/sqlkiller.(*SQLKiller).HandleSignal\n\t/data/cs/tidb/pkg/util/sqlkiller/sqlkiller.go:68\ngithub.com/pingcap/tidb/pkg/executor/internal/exec.(*executorKillerHandler).HandleSQLKillerSignal\n\t/data/cs/tidb/pkg/executor/internal/exec/executor.go:251\ngithub.com/pingcap/tidb/pkg/executor/internal/exec.Next\n\t/data/cs/tidb/pkg/executor/internal/exec/executor.go:409\ngithub.com/pingcap/tidb/pkg/executor/sortexec.(*SortExec).fetchChunksUnparallel\n\t/data/cs/tidb/pkg/executor/sortexec/sort.go:615\ngithub.com/pingcap/tidb/pkg/executor/sortexec.(*SortExec).fetchChunks\n\t/data/cs/tidb/pkg/executor/sortexec/sort.go:528\ngithub.com/pingcap/tidb/pkg/executor/sortexec.(*SortExec).Next\n\t/data/cs/tidb/pkg/executor/sortexec/sort.go:277\ngithub.com/pingcap/tidb/pkg/executor/internal/exec.Next\n\t/data/cs/tidb/pkg/executor/internal/exec/executor.go:403\ngithub.com/pingcap/tidb/pkg/executor.(*PipelinedWindowExec).fetchChild\n\t/data/cs/tidb/pkg/executor/pipelined_window.go:210\ngithub.com/pingcap/tidb/pkg/executor.(*PipelinedWindowExec).getRowsInPartition\n\t/data/cs/tidb/pkg/executor/pipelined_window.go:181\ngithub.com/pingcap/tidb/pkg/executor.(*PipelinedWindowExec).Next\n\t/data/cs/tidb/pkg/executor/pipelined_window.go:126\ngithub.com/pingcap/tidb/pkg/executor/internal/exec.Next\n\t/data/cs/tidb/pkg/executor/internal/exec/executor.go:403\ngithub.com/pingcap/tidb/pkg/executor.(*SelectionExec).Next\n\t/data/cs/tidb/pkg/executor/executor.go:1609\ngithub.com/pingcap/tidb/pkg/executor/internal/exec.Next\n\t/data/cs/tidb/pkg/executor/internal/exec/executor.go:403\ngithub.com/pingcap/tidb/pkg/executor/sortexec.(*SortExec).fetchChunksUnparallel\n\t/data/cs/tidb/pkg/executor/sortexec/sort.go:615\ngithub.com/pingcap/tidb/pkg/executor/sortexec.(*SortExec).fetchChunks\n\t/data/cs/tidb/pkg/executor/sortexec/sort.go:528\ngithub.com/pingcap/tidb/pkg/executor/sortexec.(*SortExec).Next\n\t/data/cs/tidb/pkg/executor/sortexec/sort.go:277\ngithub.com/pingcap/tidb/pkg/executor/internal/exec.Next\n\t/data/cs/tidb/pkg/executor/internal/exec/executor.go:403\ngithub.com/pingcap/tidb/pkg/executor.(*ExecStmt).next\n\t/data/cs/tidb/pkg/executor/adapter.go:1213\ngithub.com/pingcap/tidb/pkg/executor.(*recordSet).Next\n\t/data/cs/tidb/pkg/executor/adapter.go:159\ngithub.com/pingcap/tidb/pkg/server/internal/resultset.(*tidbResultSet).Next\n\t/data/cs/tidb/pkg/server/internal/resultset/resultset.go:64\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).writeChunks\n\t/data/cs/tidb/pkg/server/conn.go:2316\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).writeResultSet\n\t/data/cs/tidb/pkg/server/conn.go:2259\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).handleStmt\n\t/data/cs/tidb/pkg/server/conn.go:2052\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).handleQuery\n\t/data/cs/tidb/pkg/server/conn.go:1774\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).dispatch\n\t/data/cs/tidb/pkg/server/conn.go:1348\ngithub.com/pingcap/tidb/pkg/server.(*clientConn).Run\n\t/data/cs/tidb/pkg/server/conn.go:1114\ngithub.com/pingcap/tidb/pkg/server.(*Server).onConn\n\t/data/cs/tidb/pkg/server/server.go:739\nruntime.goexit\n\t/data/cs/go/src/runtime/asm_amd64.s:1650"]

From upper log, we can known the query is execution failed cause by maximum statement execution time exceeded, and most time is spent on RPC:

• In the first send rpc request round, cost 304ms, and we can find stats="Cop:{num_rpc:4, total_time:302.3ms}, rpc_errors:{data_is_not_ready:1, context deadline exceeded:3} from the log, and access path is:
  • {stale_read, peer:298850, store:4, err:data_is_not_ready},
  • {peer:333879, store:2, err:context deadline exceeded},
  • {replica_read, peer:298850, store:4, err:context deadline exceeded},
  • {replica_read, peer:298992, store:10, err:context deadline exceeded}
• In the second rpc request round, cost 192ms, and access path is:
  • {stale_read, peer:298850, store:4, err:data_is_not_ready}, // retry with stale-read again?
  • {peer:333879, store:2, err:context canceled}