Example 2: 3 node cluster, 1 job, Greedy job scheduler, Round Robin task scheduler

• Nodes A, B, and C fully in the cluster

• Local state before (1): {}

• Client sends submit-job (j1, tasks t1, t2) with a Round Robin task scheduler (1)

• t1 and t2 request no maximum number of peers

• A, B, and C play the log

• A, B and C encounter (1)

  • Pre: {}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 []}}}
  • adds job information to local replica
  • A sends volunteer-for-task (2)
  • B sends volunteer-for-task (3)
  • C sends volunteer-for-task (4)

• A encounters (2)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 []}}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A] :t2 []}}}
  • determines A will execute t1
  • executes t1, no reactions

• B, C encounters (2)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 []}}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A] :t2 []}}}
  • determines A will execute t1
  • ignores

• B encounters (3)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A] :t2 []}}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A] :t2 [:B]}}}
  • determines B will execute t2
  • executes t2, no reactions

• A, C encounter (3)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A] :t2 []}}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A] :t2 [:B]}}}
  • determines B will execute t2
  • ignores

• C encounters (4)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A] :t2 [:B]}}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A :C] :t2 [:B]}}}
  • determines C will execute t1
  • executes t1, no reactions

• A, B encounters (4)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A] :t2 [:B]}}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A :C] :t2 [:B]}}}
  • determines C will execute t1
  • ignores

• C completes t1, sends complete-task (5)

• A, C encounter (5)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A :C] :t2 [:B]}}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B]}} :completions {:j1 [:t1]}}
  • marks task as complete in local replica
  • A sends volunteer-for-task (6)
  • C sends volunteer-for-task (7)

• A encounters (6)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B]}} :completions {:j1 [:t1]}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A]}} :completions {:j1 [:t1]}}
  • determines A will execute t2
  • executes t2, no reactions

• C encounters (6)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B]}} :completions {:j1 [:t1]}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A]}} :completions {:j1 [:t1]}}
  • determines A will execute t2
  • ignores

• C encounters (7)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A]}} :completions {:j1 [:t1]}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A :C]}} :completions {:j1 [:t1]}}
  • determines C will execute t2
  • executes t2, no reactions

• A encounters (7)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A]}} :completions {:j1 [:t1]}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A :C]}} :completions {:j1 [:t1]}}
  • determines C will execute t2
  • ignores

• B encounters (5)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [:A :C] :t2 [:B]}}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B]}} :completions {:j1 [:t1]}}
  • marks task as complete in local replica
  • ignores, currently executing a task

• B encounters (6)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B]}} :completions {:j1 [:t1]}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A]}} :completions {:j1 [:t1]}}
  • determines A will execute t2
  • ignores

• B encounters (7)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A]}} :completions {:j1 [:t1]}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A :C]}} :completions {:j1 [:t1]}}
  • determines C will execute t2
  • ignores

• B completes t2, sends complete-task (8)

• A, B, C encounter (8)

  • Pre: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 [:B :A :C]}} :completions {:j1 [:t1]}}
  • Post: {:jobs [:j1] :tasks {:j1 [:t1 :t2]} :allocations {:j1 {:t1 [] :t2 []}} :completions {:j1 [:t1 :t2]}}
  • marks task as complete in local replica
  • A, B and C notice there are no more jobs to execute tasks for, no reactions