ERROR 2006 (HY000): MySQL server has gone away

1.バージョン
1)オペレーティングシステム
 cat/etc/issue Red Hat Enterprise Linux Server release 5.5 (Tikanga) Kernel\r on an\m
 cat/proc/version Linux version 2.6.32-504.el6.x86_64 ([email protected]) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-11) (GCC) ) #1 SMP Wed Oct 15 04:27:16 UTC 2014
2)mysqlデータベースバージョン
mysql --version mysql  Ver 14.14 Distrib 5.6.27, for Linux (x86_64) using  EditLine wrapper
2.問題の説明
ソースを使用してライブラリのエクスポートファイルをインポートすると、次のエラーが発生します.

<span style="color:#ff0000;">ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    125987
Current database: xwiki
...........
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    125988
Current database: xwiki</span><span style="color:#333333;">
...........
ERROR 1231 (42000): Variable 'time_zone' can't be set to the value of 'NULL'
ERROR 1231 (42000): Variable 'sql_mode' can't be set to the value of 'NULL'
ERROR 1231 (42000): Variable 'foreign_key_checks' can't be set to the value of 'NULL'
ERROR 1231 (42000): Variable 'unique_checks' can't be set to the value of 'NULL'
ERROR 1231 (42000): Variable 'character_set_client' can't be set to the value of 'NULL'
Query OK, 0 rows affected (0.00 sec)</span>

##ここでは、次のERROR 1231は、赤のエラーによって引き起こされる赤の部分のエラーに注目する必要があります.
3.ソリューション
その後max_を修正しましたallowed_packetパラメータは、この問題を解決しました.
1)変更を表示する前にmax_allowed_packetパラメータ

mysql> show variables like 'max_allowed%';
+--------------------+---------+
| Variable_name      | Value   |
+--------------------+---------+
| max_allowed_packet | 4194304 |
+--------------------+---------+

)max_の変更allowed_packetパラメータ

mysql> set global max_allowed_packet=16777218;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> show warnings;
+---------+------+----------------------------------------------------------+
| Level   | Code | Message                                                  |
+---------+------+----------------------------------------------------------+
| Warning | 1292 | Truncated incorrect max_allowed_packet value: '16777218' |
+---------+------+----------------------------------------------------------+
1 row in set (0.00 sec)

##注意ここで警告するのはmax_allowed_packet値は1024の整数倍でなければなりません.前例のmax_allowed_packet値は、167777218より小さい1024の最大整数倍(すなわち167777216)に設定されます.
The value should be a multiple of 1024; nonmultiples are rounded down to the nearest multiple
3)データベースを再接続しsourceを実行する
インポート成功
4.公式文書におけるmax_についてallowed_packet説明
1)
17.4.1.21 Replication and max_allowed_packet
1) max_allowed_packet  sets an upper limit on the size of any single message between the MySQL server and clients, including replication slaves. If you are replicating large column values (such as might be found in  TEXT  or  BLOB  columns) and  max_allowed_packet  is too small on the master, the master fails with an error, and the slave shuts down the I/O thread. If  max_allowed_packet  is too small on the slave, this also causes the slave to stop the I/O thread.
Row-based replication currently sends all columns and column values for updated rows from the master to the slave, including values of columns that were not actually changed by the update. This means that, when you are replicating large column values using row-based replication, you must take care to set max_allowed_packet  large enough to accommodate the largest row in any table to be replicated, even if you are replicating updates only, or you are inserting only relatively small values.
2)
  max_allowed_packet
Command-Line Format --max_allowed_packet=#
System Variable
Name max_allowed_packet
Variable Scope
Global
Dynamic Variable
Yes
Permitted Values (<= 5.6.5)
Type integer
Default 1048576
Min Value 1024
Max Value 1073741824
Permitted Values (>= 5.6.6)
Type integer
Default 4194304
Min Value 1024
Max Value 1073741824
The maximum size of one packet or any generated/intermediate string, or any parameter sent by the  mysql_stmt_send_long_data()  C API function. The default is 4MB as of MySQL 5.6.6, 1MB before that. The packet message buffer is initialized to  net_buffer_length  bytes, but can grow up to  max_allowed_packet  bytes when needed. This value by default is small, to catch large (possibly incorrect) packets. You must increase this value if you are using large  BLOB  columns or long strings. It should be as big as the largest  BLOB  you want to use. The protocol limit for max_allowed_packet  is 1GB. The value should be a multiple of 1024; nonmultiples are rounded down to the nearest multiple. When you change the message buffer size by changing the value of the  max_allowed_packet  variable, you should also change the buffer size on the client side if your client program permits it. The default  max_allowed_packet  value built in to the client library is 1GB, but individual client programs might override this. For example, mysql and mysqldump have defaults of 16MB and 24MB, respectively. They also enable you to change the client-side value by setting  max_allowed_packet  on the command line or in an option file. The session value of this variable is read only.