Peter Bacsko created YUNIKORN-1795:
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Summary: Remove the scheduling cycle in the shim
Key: YUNIKORN-1795
URL: https://issues.apache.org/jira/browse/YUNIKORN-1795
Project: Apache YuniKorn
Issue Type: Improvement
Components: shim - kubernetes
Reporter: Peter Bacsko
While debuggin/profiling YUNIKIORN-1724, the necessity of
{{Application.schedule()}} has come into question. By default, this method is
called in every second, to schedule tasks:
* if the Application state is Reserving, we only schedule placeholders
* If it is Running, then we schedule everything
* Two other states are checked (New / Accepted)
After analyzing the code, the entire state machine inside {{Application}} might
be removed, greatly simplifying the design. We can do this for the following
reasons:
# The task must not be sent to the core immediately, because we have to wait
for the application to be accepted. Until that happens, we just keep collecting
{{Task}} objects.
# As soon as an accept comes back, we just go through all tasks that we have
and schedule them. We can mark a boolean flag (eg. {{{}Application.accepted =
true{}}}), so that new incoming tasks can be scheduled immediately.
# In order to send the request to the core, we just need another extra call
after we created the {{{}Task{}}}. There's no need for the {{InitTask}} state.
# Inside {{{}Task.handleSubmitTaskEvent(){}}}, we already have the
{{Application}} object and know if it's a gang job or not. If it is and the
task is not a placeholder, we simply wait for placeholder allocations and don't
submit the task.
# If a placeholder is allocated, we can always check if it is time for the
normal pods to start running in {{{}postTaskBound(){}}}. We don't need an extra
application event for that.
With this in mind, I suggest removing {{Application.Schedule()}} method and the
{{InitTask}} state from {{{}Task{}}}. This makes the code simpler to understand
and probably even faster.
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