我使用多jdbc执行全表查询以进行数据迁移。 当我使用并行的75个jdbc查询每个表有近3000000行的差异表时，我发现MySQL在所有数据返回到jdbc之前中止了一个连接。

慢日志：

Time: 160919 9:09:38

User@Host: test[test] @ [10.142.90.20]

Thread_id: 349 Schema: mmig_1005 QC_hit: No

Query_time: 161.997180 Lock_time: 0.000560 Rows_sent: 619246 Rows_examined: 619246

Full_scan: Yes Full_join: No Tmp_table: No Tmp_table_on_disk: No

Filesort: No Filesort_on_disk: No Merge_passes: 0

explain: id select_type table type possible_keys key key_len ref rows Extra

explain: 1 SIMPLE CAR_NEW_6 ALL NULL NULL NULL NULL 2923495

use mmig_1005;

SET timestamp=1474247378;

SELECT @@version, name, id, sharding_id, model

FROM CAR_NEW_6;

表mmig_1005.car_new_6中有近3000000行，但MySQL仅发送619246行并中止了该连接。 线程ID为349，然后我在mysql-err日志中找到了此中止的连接349。

160919 9:09:38 [Warning] Aborted connection 349 to db: 'mmig_1005' user: 'test' host: '10.142.90.20' (Unknown error)

160919 9:09:38 [Warning] Aborted connection 305 to db: 'mmig_1001' user: 'test' host: '10.142.90.20' (Unknown error)

MySQL参数：

connect_timeout 10

deadlock_timeout_long 50000000

deadlock_timeout_short 10000

delayed_insert_timeout 300

innodb_flush_log_at_timeout 1

innodb_lock_wait_timeout 45

innodb_rollback_on_timeout OFF

interactive_timeout 1800

lock_wait_timeout 600

net_read_timeout 7200

net_write_timeout 7200

rpl_semi_sync_master_timeout 10000

slave_net_timeout 30

sqlasyntimeout 10

sqlasynwarntimeout 3

thread_pool_idle_timeout 60

wait_timeout 1800

innodb_log_buffer_size 134217728

max_allowed_packet 1073741824

为什么MySQL在发送所有数据之前中止该连接？