close sync with err: data len 166 < expected 3587

hi ,
the version is 1.0.40. mysql version is 5.7.20-18-log Percona Server (GPL), Release 18, Revision 7ce54a6deef.
command:
`
gh-ost_v1.0.40 --max-load=Threads_running=32 --critical-load=Threads_running=48 --chunk-size=1000 --throttle-control-replicas="xx:xx,xx:xx" --max-lag-millis=1000 --initially-drop-old-table --initially-drop-ghost-table --initially-drop-socket-file --conf="xx.cnf" --host="xx" --port="xx" --database="xx" --table="a" --verbose --alter=" add index idx_base_cust(base_cust_id)" --switch-to-rbr=false --cut-over=default --assume-rbr=true --exact-rowcount=false --default-retries=3 --critical-load-interval-millis=3000 --panic-flag-file=/tmp/ghost.panic.flag.xx.a.6601652 --postpone-cut-over-flag-file=/tmp/ghost.postpone.flag.xx.a.6601652 --throttle-flag-file=/tmp/ghost.throttle.flag.xx.a.6601652 --execute --allow-on-master
`
the log:
```
Copy: 1227096/1227096 100.0%; Applied: 2; Backlog: 0/1000; Time: 36s(total), 35s(copy); streamer: mysql-bin.000183:4056848; State: migrating; ETA: due
2018-08-09 16:17:37 INFO Reconnecting... Will resume at mysql-bin.000183:907636574
2018/08/09 16:17:37 binlogsyncer.go:75: [info] create BinlogSyncer with config &{99999 mysql xx xx xx xx false false }
2018-08-09 16:17:37 INFO Connecting binlog streamer at mysql-bin.000183:4
2018/08/09 16:17:37 binlogsyncer.go:241: [info] begin to sync binlog from position (mysql-bin.000183, 4)
2018/08/09 16:17:37 binlogsyncer.go:134: [info] register slave for master server 10.xx:xx
2018/08/09 16:17:37 binlogsyncer.go:568: [info] rotate to (mysql-bin.000183, 4)
2018-08-09 16:17:37 INFO rotate to next log name: mysql-bin.000183
2018/08/09 16:17:37 binlogstreamer.go:47: [error] close sync with err: data len 166 < expected 3587
2018-08-09 16:17:37 INFO StreamEvents encountered unexpected error: data len 166 < expected 3587
Copy: 1227096/1227096 100.0%; Applied: 2; Backlog: 0/1000; Time: 37s(total), 35s(copy); streamer: mysql-bin.000183:4062381; State: migrating; ETA: due
Copy: 1227096/1227096 100.0%; Applied: 2; Backlog: 0/1000; Time: 38s(total), 35s(copy); streamer: mysql-bin.000183:4062381; State: migrating; ETA: due
2018-08-09 16:17:39 ERROR Timeout while waiting for events up to lock
2018-08-09 16:17:39 ERROR 2018-08-09 16:17:39 ERROR Timeout while waiting for events up to lock
2018-08-09 16:17:39 INFO Looking for magic cut-over table
2018-08-09 16:17:39 INFO Will now proceed to drop magic table and unlock tables
2018-08-09 16:17:39 INFO Dropping magic cut-over table
2018-08-09 16:17:39 INFO Dropping magic cut-over table
2018-08-09 16:17:39 INFO Droppping table `xx`.`_a_del`
2018-08-09 16:17:39 INFO Table dropped
2018-08-09 16:17:39 INFO Releasing lock from `xx`.`a`, `xx`.`_a_del`
2018-08-09 16:17:39 INFO Tables unlocked
Copy: 1227096/1227096 100.0%; Applied: 2; Backlog: 0/1000; Time: 39s(total), 35s(copy); streamer: mysql-bin.000183:4062381; State: migrating; ETA: due
2018-08-09 16:17:40 INFO Grabbing voluntary lock: gh-ost.8482269.lock
2018-08-09 16:17:40 INFO Setting LOCK timeout as 6 seconds
2018-08-09 16:17:40 INFO Looking for magic cut-over table
2018-08-09 16:17:40 INFO Creating magic cut-over table `xx`.`_a_del`
2018-08-09 16:17:40 INFO Magic cut-over table created
2018-08-09 16:17:40 INFO Locking `xx`.`a`, `xx`.`_a_del`
2018-08-09 16:17:40 INFO Tables locked
2018-08-09 16:17:40 INFO Session locking original & magic tables is 8482269
2018-08-09 16:17:40 INFO Writing changelog state: AllEventsUpToLockProcessed:1533802660582469107
2018-08-09 16:17:40 INFO Waiting for events up to lock
Copy: 1227096/1227096 100.0%; Applied: 2; Backlog: 0/1000; Time: 40s(total), 35s(copy); streamer: mysql-bin.000183:4062381; State: migrating; ETA: due
Copy: 1227096/1227096 100.0%; Applied: 2; Backlog: 0/1000; Time: 41s(total), 35s(copy); streamer: mysql-bin.000183:4062381; State: migrating; ETA: due
2018-08-09 16:17:42 FATAL 4 successive failures in streamer reconnect at coordinates mysql-bin.000183:4
```
the table :
```
CREATE TABLE `a` (
`id` bigint(20) NOT NULL AUTO_INCREMENT ,
`tenant_id` int(10) DEFAULT '0' ,
`biz_line_id` int(10) NOT NULL DEFAULT '0' ,
`customer_type_id` int(10) NOT NULL DEFAULT '0' ,
`base_cust_id` bigint(20) NOT NULL ,
`cust_id` bigint(20) NOT NULL,
`sub_biz_line_id` int(10) NOT NULL DEFAULT '0' ,
`is_deleted` tinyint(1) DEFAULT '0' ,
`gmt_created` datetime DEFAULT NULL ,
`creator` int(10) DEFAULT '0' ,
`gmt_modified` datetime DEFAULT NULL ,
`modifier` int(10) DEFAULT '0' ,
PRIMARY KEY (`id`),
UNIQUE KEY `uk_cust_sub_biz_line` (`cust_id`,`sub_biz_line_id`),
KEY `idx_sub_biz_line_tenant_type` (`sub_biz_line_id`,`biz_line_id`,`tenant_id`,`customer_type_id`),
KEY `idx_base_cust` (`base_cust_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1338565 DEFAULT CHARSET=utf8mb4
```
I have run this command about 3 times with both release code and the latest master code. Is there and clues about what happened and how to fix it? Thanks!