1.进行矩阵计算的时候，由于持续时间长，往往会出现超时的错误，错误内容如下： INFO mapreduce.Job: Task Id : attempt_1422500209602_0008_m_000000_0, Status : FAILED
AttemptID:attempt_1422500209602_0008_m_000000_0 Timed out after 600 secs
有两种办法可以修复
1）解决办法是在代码中定时report context.progress();
2）in mapred-site.xml添加或者修改
mapred.task.timeout
1800000
2.You have an error in your SQL syntax; check the manual that corresponds to your MySQL serv
er version for the right syntax to use near 'OPTION SQL_SELECT_LIMIT=DEFAULT' at line 1
Mysql-connector-java.jar版本太低，方法不支持
3.Current usage: 280.1 MB of 1 GB physical memory used; 2.7 GB of 2.1 GB virtual me
mory used. Killing container.
清除jvm
Jvm分配情况，清除mapred-site.xml配置
<property>
<name>mapred.child.java.opts</name>
<value>-Xmx1024m</value>
</property>
这个配置影响
