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In the previous exercise, we showed how ecflow provides simple load management.

The limits can still allow several hundred jobs to be submitted at once. This can cause problems:

• Excessive disk/io in job generation
• Server busy in job generation, and slow to respond to the GUI.
• Overload queueing queuing systems like PBS/SLURM

Hence we need

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load management that can limit the number of

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submissions. When the Job becomes active the limit token is released.

This exercise shows the use of '-s' option. Which helps to control the number of tasks in the submitted state.

We can have more than 2 active jobs since we only control the number in the submitted state.

If we removed the -s then we can only have two active jobs running at one time

The use of -s  allows the configuration of the suite, depending on the load the disk/io and queuing system can sustain.

Here is the simple illustration that modifies the previous example:

Text

Let us modify our suite definition file:

# Definition of the suite test.
suite test
 edit ECF_INCLUDE "$HOME/course"
 edit ECF_HOME    "$HOME/course"
 limit l1 2

 family f5
     inlimit -s l1 # by default consume 1 token from the limit l1
     edit SLEEP 20
     task t1
     task t2
     task t3
     task t4
     task t5
     task t6
     task t7
     task t8
     task t9
 endfamily
endsuite

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import os
from ecflow import Defs,Suite,Family,Task,Edit,Trigger,Complete,Event,Meter,Time,Day,Date,Label, \
                   RepeatString,RepeatInteger,RepeatDate,InLimit,Limit
        
def create_family_f5() :
    return Family("f5",
            # limit_name(l1),limit_path(""),no_of_tokens_to_consume(1),limit node(False), limit submission(True)
            InLimit("l1","",1,False,True), 
            Edit(SLEEP=20),
            [ Task('t{}'.format(i)) for i in range(1,10) ] )
    
print("Creating suite definition")  
home = os.path.join(os.getenv("HOME"),"course")
defs = Defs( 
        Suite("test",
            Edit(ECF_INCLUDE=home,ECF_HOME=home),
            Limit("l1",2),
            create_family_f5()))
print(defs) 

print("Checking job creation: .ecf -> .job0")  
print(defs.check_job_creation())

print("Checking trigger expressions and inlimits")
assert len(defs.check()) == 0,defs.check() 

print("Saving definition to file 'test.def'")
defs.save_as_defs("test.def")

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1. Edit the changes
2. Replace the suite definition
3. In ecflow_ui , observe the triggers of the limit l1Open the Info panel for l1effects
4. Change the value of the limit
5. Open the Why? panel for one of the queued tasks of /test/f5
6.  and inlimit, observe the effect.

   
   

   Introduce an error in the limits and make sure this error is trapped. i.e. change the Limit.

   Code Block
   language py title Check InLimit/Limit references
   Limit("unknown",2)