org.apache.tez.dag.api.SessionNotRunning: TezSession has already shutdown. Application application_1

报错信息：
org.apache.tez.dag.api.SessionNotRunning: TezSession has already shutdown. Application application_1574002486205_0005 failed 2 times due to AM Container for appattempt_1574002486205_0005_000002 exited with exitCode: -103
For more detailed output, check application tracking page:http://cts01:8088/cluster/app/application_1574002486205_0005Then, click on links to logs of each attempt.
Diagnostics: Container [pid=10060,containerID=container_1574002486205_0005_02_000001] is running beyond virtual memory limits. Current usage: 182.4 MB of 1 GB physical memory used; 2.6 GB of 2.1 GB virtual memory used. Killing container.

报错原因：
该错误是YARN的虚拟内存计算方式导致，上例中用户程序申请的内存为1Gb，YARN根据此值乘以一个比例（默认为2.1）得出申请的虚拟内存的值，当YARN计算的用户程序所需虚拟内存值大于计算出来的值时，就会报出以上错误。调节比例值可以解决该问题。具体参数为：yarn-site.xml中的yarn.nodemanager.vmem-pmem-ratio

解决方案：
第一，关掉虚拟内存检查
修改yarn-site.xml

<property>
<name>yarn.nodemanager.vmem-check-enabled</name>
<value>false</value>
</property>

第二，mapred-site.xml中设置Map和Reduce任务的内存配置如下：(value中实际配置的内存需要根据自己机器内存大小及应用情况进行修改)

<property>
　　<name>mapreduce.map.memory.mb</name>
　　<value>1536</value>
</property>
<property>
　　<name>mapreduce.map.java.opts</name>
　　<value>-Xmx1024M</value>
</property>
<property>
　　<name>mapreduce.reduce.memory.mb</name>
　　<value>3072</value>
</property>
<property>
　　<name>mapreduce.reduce.java.opts</name>
　　<value>-Xmx2560M</value>
</property>

第三，调整hadoop配置文件yarn-site.xml中值

<property>
   <name>yarn.scheduler.minimum-allocation-mb</name>
   <value>2048</value>
   <description>default value is 1024</description>
</property>
<property>
    <name>yarn.nodemanager.vmem-pmem-ratio</name>
    <value>2.1</value>
    <description>default value is 2.1</description>
</property>

增加yarn.scheduler.minimum-allocation-mb 数量，从缺省1024改为2048；上述运行问题即刻得到解决；
单独调整yarn.nodemanager.vmem-pmem-ratio从缺省值2.1调整到3.0，从计算上Vm=3.0*1=3.0>2.6