Thank you Aaron for the reply,

Specifically I am trying to run what in chemistry is known as an Umbrella Samplig simulation, in which independent simulation windows are run. The total number of windows for the whole simulation is 104, but allocating 104 cores to perform the simulation would signify a long wait time in the queue. So, sometime ago I found a solution to this in the execution of an array, which will take profit of idle cores and that will run the jos sequentially. That is launch n array jobs (lets say 30) of the total number of jobs (i.e. 104) and after each job finishes the new window is started in case the resource is available. All the simulation windows are independent from each other and runs for more or less the same time. My problem is that if the maximum number of jobs in the queue is set to a low value, the array is launched to reach the maxjobslimit although a higher number of cores are free. Sorry if I am not so clear, but I am not a computer scientist :-)

El 19/12/2018 a las 12:25, Aaron Knister escribió:
Alfredo,

I’m assuming the resources are used initially in some sort of tightly-coupled 
parallel task, or at least some workload where all the tasks finish at about 
the same time. I’m wondering and also assuming that the tasks you’re looking to 
run afterwards as part of an array are less tightly coupled. Does this mean 
there might be significant variation in the runtime of those tasks? I’m curious 
if your desire here is to have those array jobs treated as individual 
allocations so that resources can free up as tasks complete (e.g so that you’re 
not holding up 30 processors if just one of the tasks takes significantly 
longer to complete than the others).

Sent from my iPhone

On Dec 18, 2018, at 12:03, Alfredo Quevedo <maquevedo....@gmail.com> wrote:

Dear slurm users,

I would like to know if it is possible to prepare a slurm submission script in 
a way that initially CPU resources are requested (lets say 30 CPUs), and 
afterwards, the assigned resources are used to launch an array of 30 single CPU 
jobs array? I would greatly appreciate any hint in this respect

Thanks in advance

Alfredo



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