今天为了解决别的问题，把/etc/hosts文件里的 127.0.0.1 localhost改成了  127.0.0.1  DSETL ，结果运行作业的时候就报这个错：Failed to connect to JobMonApp on port 13491。作业能够运行不会报错，但是无法监控，看得到日志，但是看不到运行情况（数据条数）
在官网上找到了如下解释：

Problem(Abstract)

DataStage job run statistics (i.e. rows per second processed) do not update in DataStage Designer or Director clients.

Diagnosing the problem

This section contains a quick series of diagnosis steps for those familiar with DataStage and Job monitor. If more detail is needed for any step, please refer to the more detailed instructions in the "Resolving the Problem" section:
If customer has checked and verified that the following:

1. Check the DataStage Director job log for jobs which do not not
   show job run statistics and confirm whether the following variable is
   defined:
   APT_NO_JOBMON
   If APT_NO_JOBMON is defined and set to
   value of 1 or true, then it will disable job monitoring and process
   metadata reporting for parallel jobs.
2. Confirm the JobMonApp process is up and running:
   ps -ef | grep JobMonApp
3. Confirm default ports 13400 and 13401 are listening:
   netstat -an | grep 134
4. Check job monitor log file for errors:
   cat /ibm/InformationServer/Server/PXEngine/java/JobMonApp.log
5. Confirm job monitor is setup to use ports 13400 and 13401
   cat /ibm/InformationServer/Server/PXEngine/etc/jobmon_ports
6. If job monitor log shows no errors but job log reports "Failed
   to connect to JobMonApp on port 13401" then update jobmon_ports file to
   use 2 new ports which are not already in use. This will require restart
   of JobMonApp.
7. If problem still occurs, confirm that /etc/hosts file contains the following entry
   127.0.0.1 localhost
   without a localhost entry, Job Monitor will be unable to use the ports correctly.
8. Confirm localhost resolves to 127.0.0.1 by using ping
   ping localhost
   this should resolve to 127.0.0.1