The document outlines CJ Grady's thesis defense on optimizing sea level rise inundation delineation. It discusses using Dijkstra's algorithm to calculate minimum inundation height while accounting for barriers. It explores using different data structures like binary heaps and Fibonacci heaps for the priority queue in Dijkstra's algorithm. It also presents a parallel approach using a master-worker model to improve performance for large datasets deployed on supercomputing resources.

1. Delineating Sea-Level Rise
Inundation: An Exploration of
Data Structures and
Performance Optimization
CJ Grady
Thesis defense
May 10, 2017

2. Outline
 Introduction
 Sea level rise inundation delineation and inundation height
 Data structures for inundation height calculation
 Parallelizing inundation height calculation
 Conclusions

3. Introduction
 An estimated 25% of people live within 100 km and at
elevations less than 100 m
 As sea level continues to rise, it is critical to know which areas
might be inundated in order to predict and mitigate
economic and environmental impacts
 First we present an approach for calculating inundation height
that accounts for barriers based on Dijkstra’s algorithm
 Data structures
 Next we developed a parallel method for calculating
inundation height that can be deployed on supercomputing
resources

4. Sea Level Rise Inundation--Bathtub
Method
 Any cell with a lower elevation than a specified sea level rise is
inundated
 Pros:
 Simple computation
 Cons:
 Specific sea level rise
 Does not account for water connectivity

5. Inundation Height
 Uses Dijkstra’s algorithm to calculate minimum inundation
height for every cell
 Pros:
 Accounts for water connectivity
 Inundation height for every cell
 Cons:
 Computationally expensive

6. Calculating Inundation Height Using
Dijkstra’s Algorithm
 Inundation height is not simply elevation
 Barriers can prevent water propagation
 We used Dijkstra’s algorithm to determine the minimum sea
level rise required to inundate
 We then explored the priority queue data structure used in
the algorithm

7. Dijkstra’s Algorithm for inundation height
 Maintains a set of connected nodes (propagation front) in a
priority queue data structure
 Selects the connected node with the least height and removes
it from the set
 Adds the nodes connected to this newly visited node to the
connected nodes set
 Updates heights as necessary
 Repeats until the connected nodes set is empty

9. North Carolina DEM

10. 𝑒𝑟𝑟𝑜𝑟 % =
𝐵𝑎𝑡ℎ𝑡𝑢𝑏 𝐼𝑛𝑢𝑛𝑑𝑎𝑡𝑖𝑜𝑛 − 𝑂𝑢𝑟 𝐼𝑛𝑢𝑛𝑑𝑎𝑡𝑖𝑜𝑛
𝑂𝑢𝑟 𝐼𝑛𝑢𝑛𝑑𝑎𝑡𝑖𝑜𝑛
Bathtub vs Method Considering Water
Connectivity

11. Addressing Performance With Data
Structures
 Dijkstra’s algorithm relies on a priority queue
 First implementation used a binary heap
 Fibonacci heap provides better asymptotic performance for
multiple operations

12. Binary Heap vs Fibonacci Heap
Operation Binary Heap Fibonacci Heap
Push Θ(log n) Θ(1)
Pop Θ(log n) * O(log n)
Reduce Key Θ(log n) Θ(1)
Find Minimum Θ(1) Θ(1)
* - Amortized cost

13. Binary Heap vs Fibonacci Heap
 In theory, Fibonacci Heap has better performance
 The main advantage of Fibonacci Heap is the reduce key
method
 Reduce key is not used for inundation height
 The constant associated with the pop operation is greater for
Fibonacci Heaps
 This causes Fibonacci Heap to be slower (10x in this case)

14. Parallelizing Inundation Height
Calculations
 The performance of our first method does not scale
 We developed a parallel approach for Dijkstra calculations
 Master / worker paradigm
 Deployed on XSEDE resources

15. Literature Review
 Other cost distance algorithms
 Bellman-Ford, A*
 Parallel versions of Dijkstra’s algorithm
 Parallelization of heap
 Parallelization of edge processing
 Parallel computations
 MrGeo

16. NGDC CRM Dataset

17. Florida Volume

18. Single Tile

19. Three Concepts
 Region decomposition
 Calculate-and-correct
 Parallel computations

20. Region Decomposition

21. Calculate-and-correct
 Computations are run with the information available
 As computations complete for a tile, the edges are exported
to adjacent tiles to be used as inputs
 Computations continue until no changes are made

22. Calculate-and-correct Initial Profile

23. Calculate-and-correct Inundation From
Left

24. Calculate-and-correct Corrected

25. A Complete Example

26. 3 5 3 2 1
2 2 3 4 4
2 1 9 9 7
0 1 8 3 3
1 3 7 3 3
1 4 6 4 3
1 3 5 2 2
1 1 6 2 2
1 1 1 8 9
0 1 1 2 2
1 0 1 2 2
5 4 1 2 3
9 8 5 5 4
2 7 4 6 4
2 9 8 7 5
3 2 8 4 4
2 2 2 2 3
2 9 2 2 3
8 6 1 1 1
1 1 1 1 1

27. Edge Vector Export

28. 3 5 3 2 1
2 2 3 4 4
2 1 9 9 7
0 1 8 3 3
1 3 7 3 3
1 4 6 4 3
1 3 5 2 2
1 1 6 2 2
1 1 1 8 9
0 1 1 2 2
1 0 1 2 2
5 4 1 2 3
9 8 5 5 4
2 7 4 6 4
2 9 8 7 5
3 2 8 4 4
2 2 2 2 3
2 9 2 2 3
8 6 1 1 1
1 1 1 1 1
Running:
• Top left
• Top right
• Bottom left
• Bottom right

29. -/3 -/5 -/3 -/2 -/1
-/2 -/2 -/3 -/4 -/4
-/2 1/1 -/9 -/9 -/7
0/0 1/1 -/8 -/3 -/3
1/1 -/3 -/7 -/3 -/3
-/1 -/4 -/6 -/4 -/3
-/1 -/3 -/5 -/2 -/2
-/1 -/1 -/6 -/2 -/2
1/1 1/1 -/1 -/8 -/9
0/0 1/1 -/1 -/2 -/2
1/1 0/0 1/1 -/2 -/2
-/5 -/4 1/1 -/2 -/3
-/9 -/8 -/5 -/5 -/4
-/2 -/7 -/4 -/6 -/4
-/2 -/9 -/8 -/7 -/5
-/3 -/2 -/8 -/4 -/4
-/2 -/2 -/2 -/2 -/3
-/2 -/9 -/2 -/2 -/3
-/8 -/6 -/1 -/1 -/1
-/1 -/1 -/1 -/1 -/1
Running:
• Top left
• Top right
• Bottom left
Idle:
• Bottom right

30. 3/3 5/5 3/3 3/2 3/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 7/3 7/3
1/1 3/3 7/7 7/3 7/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
8/2 8/7 5/4 6/6 4/4
8/2 9/9 8/8 7/7 5/5
-/3 -/2 -/8 -/4 -/4
-/2 -/2 -/2 -/2 -/3
-/2 -/9 -/2 -/2 -/3
-/8 -/6 -/1 -/1 -/1
-/1 -/1 -/1 -/1 -/1
Running:
• Top left
• Top right
Waiting:
• Top left
• From BL
Idle:
• Bottom left
Submitted:
• Bottom right
• From BL

31. 3/3 5/5 3/3 3/2 3/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 7/3 7/3
1/1 3/3 7/7 7/3 7/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
8/2 8/7 5/4 6/6 4/4
8/2 9/9 8/8 7/7 5/5
-/3 -/2 -/8 -/4 -/4
-/2 -/2 -/2 -/2 -/3
-/2 -/9 -/2 -/2 -/3
-/8 -/6 -/1 -/1 -/1
2/1 2/1 -/1 -/1 -/1
Running:
• Top left
• Bottom right
Waiting:
• Top left
• From BL
• From TR
• Bottom right
• From TR
Idle:
• Bottom left
• Top right
5/3
5/2
5/2
9/9
2/2

32. 3/3 5/5 3/3 3/2 3/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 7/3 7/3
1/1 3/3 7/7 7/3 7/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
8/2 8/7 5/4 6/6 4/4
8/2 9/9 8/8 7/7 5/5
-/3 -/2 -/8 -/4 -/4
-/2 -/2 -/2 -/2 -/3
-/2 -/9 -/2 -/2 -/3
-/8 -/6 -/1 -/1 -/1
2/1 2/1 2/1 2/1 -/1
Running:
• Bottom right
Waiting:
• Bottom right
• From TR
Submitted:
• Top left
• From BL
• From TR
• Top right
• From TL
• Bottom left
• From TL
5/3
5/2
5/2
9/9
2/2

33. 3/3 5/5 3/3 3/2 3/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 7/3 7/3
1/1 3/3 7/7 7/3 7/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
8/2 8/7 5/4 6/6 4/4
8/2 9/9 8/8 7/7 5/5
-/3 -/2 -/8 -/4 -/4
-/2 -/2 -/2 -/2 -/3
-/2 -/9 -/2 -/2 -/3
-/8 -/6 2/1 2/1 -/1
2/1 2/1 2/1 2/1 2/1
Running:
• Bottom right
• Top left
• Top right
Idle:
• Bottom left
Waiting:
• Bottom right
• From TR
5/3
5/2
5/2
9/9
2/2
1/1
5/5
9/9
8/2
8/2
1/1 3/3 7/7 7/3 7/3
1/1 4/4 6/6 5/4 5/3
3/1
4/4
7/7
7/3
7/3

34. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 7/3 7/3
1/1 3/3 7/7 5/3 7/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
7/2 7/7 5/4 6/6 4/4
7/2 9/9 8/8 7/7 5/5
-/3 -/2 -/8 -/4 -/4
-/2 -/2 -/2 -/2 -/3
-/2 -/9 2/2 2/2 -/3
-/8 -/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Running:
• Bottom right
• Top left
Idle:
• Bottom left
• Top right
Waiting:
• Bottom right
• From TR
5/3
5/2
5/2
9/9
2/2
1/1
5/5
9/9
8/2
8/2
1/1 4/4 6/6 5/4 5/3
3/1
4/4
7/7
7/3
7/3

35. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 5/3 5/3
1/1 3/3 7/7 5/3 5/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
7/2 7/7 5/4 6/6 4/4
7/2 9/9 8/8 7/7 5/5
-/3 -/2 -/8 -/4 -/4
-/2 2/2 2/2 2/2 -/3
-/2 -/9 2/2 2/2 -/3
-/8 -/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Running:
• Bottom right
Idle:
• Bottom left
• Top left
Waiting:
• Bottom right
• From TR
Submitted:
• Top right
• From TL
5/3
5/2
5/2
9/9
2/2
1/1
5/5
9/9
5/2
5/2
1/1 4/4 6/6 5/4 5/3

36. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 5/3 5/3
1/1 3/3 7/7 5/3 5/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
5/2 7/7 5/4 6/6 4/4
5/2 9/9 8/8 7/7 5/5
-/3 2/2 -/8 -/4 -/4
2/2 2/2 2/2 2/2 -/3
2/2 -/9 2/2 2/2 -/3
-/8 -/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Running:
• Bottom right
Idle:
• Bottom left
• Top left
• Top right
Waiting:
• Bottom right
• From TR
5/3
2/2
2/2
9/9
2/2
1/1
4/4
7/7
5/3
5/3

37. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 5/3 5/3
1/1 3/3 7/7 5/3 5/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
5/2 7/7 5/4 6/6 4/4
5/2 9/9 8/8 7/7 5/5
3/3 2/2 8/8 4/4 4/4
2/2 2/2 2/2 2/2 3/3
2/2 9/9 2/2 2/2 3/3
8/8 6/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Idle:
• Top left
Submitted:
• Top right
• From BR
• Bottom left
• From BR
• Bottom right
• From TR
3/3
2/2
2/2
9/9
2/2

38. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 5/3 5/3
1/1 3/3 7/7 5/3 5/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 5/2
1/1 1/1 6/6 5/2 5/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
5/2 7/7 5/4 6/6 4/4
5/2 9/9 8/8 7/7 5/5
3/3 2/2 8/8 4/4 4/4
2/2 2/2 2/2 2/2 3/3
2/2 9/9 2/2 2/2 3/3
8/8 6/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Running:
• Top right
• Bottom left
Idle:
• Top left
• Bottom right
3/3 2/2 8/8 4/4 4/4
5/2 9/9 8/8 7/7 5/5
3/3
2/2
2/2
8/8
2/1

39. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 5/3 5/3
1/1 3/3 7/7 5/3 5/3
1/1 4/4 6/6 5/4 5/3
1/1 3/3 5/5 5/2 2/2
1/1 1/1 6/6 5/2 2/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
3/2 7/7 5/4 6/6 4/4
3/2 9/9 8/8 7/7 5/5
3/3 2/2 8/8 4/4 4/4
2/2 2/2 2/2 2/2 3/3
2/2 9/9 2/2 2/2 3/3
8/8 6/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Running:
• Bottom left
Idle:
• Bottom right
• Top right
Submitted:
• Top left
• From TR
3/3 2/2 8/8 4/4 4/4
3/3
2/2
2/2
8/8
2/1

40. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 3/3 3/3
1/1 3/3 7/7 5/3 3/3
1/1 4/4 6/6 4/4 3/3
1/1 3/3 5/5 2/2 2/2
1/1 1/1 6/6 2/2 2/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
3/2 7/7 5/4 6/6 4/4
3/2 9/9 8/8 7/7 5/5
3/3 2/2 8/8 4/4 4/4
2/2 2/2 2/2 2/2 3/3
2/2 9/9 2/2 2/2 3/3
8/8 6/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Running:
• Top left
Idle:
• Bottom right
• Top right
• Bottom left
Waiting:
• Top left
• From BL
3/3
2/2
2/2
8/8
2/1
1/1
5/5
9/9
3/2
3/2

41. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 3/3 3/3
1/1 3/3 7/7 3/3 3/3
1/1 4/4 6/6 4/4 3/3
1/1 3/3 5/5 2/2 2/2
1/1 1/1 6/6 2/2 2/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
3/2 7/7 5/4 6/6 4/4
3/2 9/9 8/8 7/7 5/5
3/3 2/2 8/8 4/4 4/4
2/2 2/2 2/2 2/2 3/3
2/2 9/9 2/2 2/2 3/3
8/8 6/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Idle:
• Bottom right
• Top right
Submitted:
• Top left
• From BL
• Bottom left
• From TL
1/1
5/5
9/9
3/2
3/2

42. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 3/3 3/3
1/1 3/3 7/7 3/3 3/3
1/1 4/4 6/6 4/4 3/3
1/1 3/3 5/5 2/2 2/2
1/1 1/1 6/6 2/2 2/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
3/2 7/7 5/4 6/6 4/4
3/2 9/9 8/8 7/7 5/5
3/3 2/2 8/8 4/4 4/4
2/2 2/2 2/2 2/2 3/3
2/2 9/9 2/2 2/2 3/3
8/8 6/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Running:
• Top left
Idle:
• Bottom right
• Top right
• Bottom left
1/1 3/3 7/7 3/3 3/3
1/1 4/4 6/6 4/4 3/3

43. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 3/3 3/3
1/1 3/3 7/7 3/3 3/3
1/1 4/4 6/6 4/4 3/3
1/1 3/3 5/5 2/2 2/2
1/1 1/1 6/6 2/2 2/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
3/2 7/7 5/4 6/6 4/4
3/2 9/9 8/8 7/7 5/5
3/3 2/2 8/8 4/4 4/4
2/2 2/2 2/2 2/2 3/3
2/2 9/9 2/2 2/2 3/3
8/8 6/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1
Idle:
• Bottom right
• Top right
• Bottom left
• Top left
1/1 4/4 6/6 4/4 3/3

44. 3/3 5/5 3/3 2/2 1/1
2/2 2/2 3/3 4/4 4/4
2/2 1/1 9/9 9/9 7/7
0/0 1/1 8/8 3/3 3/3
1/1 3/3 7/7 3/3 3/3
1/1 4/4 6/6 4/4 3/3
1/1 3/3 5/5 2/2 2/2
1/1 1/1 6/6 2/2 2/2
1/1 1/1 1/1 8/8 9/9
0/0 1/1 1/1 2/2 2/2
1/1 0/0 1/1 2/2 2/2
5/5 4/4 1/1 2/2 3/3
9/9 8/8 5/5 5/5 4/4
3/2 7/7 5/4 6/6 4/4
3/2 9/9 8/8 7/7 5/5
3/3 2/2 8/8 4/4 4/4
2/2 2/2 2/2 2/2 3/3
2/2 9/9 2/2 2/2 3/3
8/8 6/6 2/1 2/1 2/1
2/1 2/1 2/1 2/1 2/1

45. Expand / Contract Edge Vectors

46. Parallelism
 Master / worker
 Master submits computations
 Workers run computations on tiles and report back
 Updated inundation height tiles
 Edge vectors

47. Master / Worker
Master Process
(Work Queue)
Worker Worker Worker Worker…

48. Master / Worker
 Uses Work Queue from Notre Dame
 Roughly one worker per core
 Can be deployed on:
 One machine
 A cluster
 Across heterogeneous resources

49. Parallelism
 Continuous flow of computations rather than map reduce
style
 Eliminates some resource starvation
 Locks tiles to prevent race conditions
 Master limits tasks to one per tile

50. Experiments
 Single layer for the NGDC dataset
 Parallelization on single machine with 1, 2, 4, 8, 12 cores and
with half degree, one degree, and two degree tile sizes
 Parallelization on XSEDE Stampede with 32, 64, 128 cores and
with half degree, one degree, and two degree tile sizes
 West coast and entire NGDC dataset

51. Experiments—Single Layer for the NGDC
dataset
 Merged all of the NGDC dataset
 Computations did not fit into memory
 Had to cut down data size (West Coast) to run serially

52. West Coast Experiment

53. 0
1000
2000
3000
4000
5000
6000
1-0.5 1-1.0 1-2.0 2-0.5 2-1.0 2-2.0 4-0.5 4-1.0 4-2.0 8-0.5 8-1.0 8-2.0 12-0.5 12-1.0 12-2.0
RunningTime(s)
Number of Workers - Tile Size (dd)
Serial Method
West Coast Experiment Running Times

54. West Coast Experiment Data

55. Entire NGDC Dataset Experiment
 Could not run serial version on available hardware
 Ran on single machine with 1, 2, 4, 8, 12 cores
 Ran on Stampede with 32, 64, 128 cores
 Ran with half degree, one degree, and two degree tile sizes

56. Stampede
 XSEDE (Extreme Science and Engineering Discovery
Environment) resource
 Housed at Texas Advanced Computing Center
 2+ petaFLOPs for main cluster
 6400 Compute Nodes
 Lustre file system (parallel file storage)
 Decommission began in January 2017

57. Stampede Deployment
M W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
W W
…
Lustre
Parallel File
Storage

58. 1 2 4 8 12 31 63 127
Half Degree 13499 6828 3461 2290 2280 861 556 1486
One Degree 13077 6675 3402 2324 2259 905 1573 1455
Two Degree 13575 6944 3509 2474 2397 964 626 510
0
2000
4000
6000
8000
10000
12000
14000
16000
RunningTime(seconds)
Number of Workers
Half Degree One Degree Two Degree
Experiment Results

59. Conclusions
 Dijkstra’s algorithm allows us to calculate inundation height
from DEM
 Heap data structures significantly improve the efficiency
 Parallel implementation addresses scale up Dijkstra’s
algorithm
 Running time
 Memory footprint
 Parallelization can be applied to supercomputing resources

60. Future Work
 Overcome new bottlenecks in parallelization method
 Other resource may be more appropriate (such as TACC’s Wrangler)
 New framework for parallelization spatially dependent
calculations