Manual

When zombie s arise they can be handled manually by ecflowview. (See Zombie) or via the command line interface:

Sometimes we may want the job to proceed but  "ecflow_client –zombie_adopt <task-path>" does not work. i.e we have the case where zombies password matches, but the process id (ECF_RID) are different.

ecflow_client –zombie_adopt <task-path>, will not allow this, due to the potential for data corruption. 

In this case the normal behaviour would be kill both process, and re-queue the task.

 

In the extreme, we can by pass the authentication. (i.e allowing the request to be handled by the server).

This should ONLY be done when you are sure the zombie has been killed, and you don’t want to re-queue the job.

    > ecflow_client --alter add variable ECF_PASS FREE  < path to task>

This is also available from the GUI. Select the task. RMB->Special-> Free password.

After the job has completed, be sure to delete this variable. Otherwise if zombies arise again, there is a considerable risk of data corruption.

Automated

It is also possible to ask ecflow_server to make the same response in an automated fashion. How ever very careful consideration should be made before doing this. Otherwise it could mask a serious underlying problem.

The automated response can be defined statically using python and text interface or dynamically (add/remove) via alter.:

The zombie attribute is inherited in the same manner as Variable inheritance.

Example: For tasks under suite “s1” add a zombie attribute, such that child label commands(i.e ecflow_client –label) never blocks the job: (not strictly needed as this is the default behaviour from release 4.0.5 onwards)

Example: For tasks under suite “s1” add a zombie attribute, such that job that issues the child commands( event, meter, label) never blocks: (not strictly needed as this is the default behaviour from release 4.0.5 onwards)

Example: For all tasks under family “critical”, if any zombies arise then fail the job:

 

Here are some further example of using --alter:

You can only add one zombie attribute of each time(ecf,path,user).

To delete a zombie attribute, please use one of:

Here are some more examples:

       ecflow_client --alter add zombie "ecf:kill:init,complete:" /suiteZ

             ecflow_client --alter add zombie "user:kill::" /suiteZ

       ecflow_client --alter add zombie "ecf:adopt:complete:" /suiteZ

Semi-Automated

Sometimes zombies can arise for more obscure reasons. i.e The job sends a --init message to the server, meanwhile the server is busy(i.e processing jobs), when finally the server makes the task active, and sends a message back to the client/job, the ecflow_client has timed out. This causes the ecflow_client to send the same message again. However this time the server treats the child command as a zombie, since the task is already active. Hence we get these false zombies.

These scenario's are very rare, but tends to happen, for the following situations:

To diagnose these cases, we need to look at the log file. Typically you will see two or more child commands (--init/complete), where the second will then be treated as a zombie.

To get round these issue you can add a variable ECF_NONSTRICT_ZOMBIES, which will reduce these false zombies.

       ecflow_client --alter add variable ECF_NONSTRICT_ZOMBIES 1 /              # adds the variable to the root/server level, and hence affect all suites on the server

       ecflow_client --alter add variable ECF_NONSTRICT_ZOMBIES 1 /suiteX      # adds the variable at the suite level,, and hence only affects this suite.