我一直在开发一个小程序，该程序使用 OpenMP 计算给定图中每个顶点的最短路径，以在多个线程之间拆分计算，而不是一次执行一个顶点。虽然我当前的实现有效，但我想这样做，以便我可以从格式为“vertex1 vertex2 weight”的文件中读取图形数据，这样图形就不会被硬编码到程序中。
来源在这里： http: //pastebin.com/bkR7QysB
编译如下：
g++ -fopenmp GraphTest.cpp WeightedGraph.cpp -o dijkstra
使用以下数据作为输入：
foo derp 50
narf balls 30
foo balls 20
balls derp 60
derp narf 40
derp cox 30
foo narf 50
narf pie 99
cox pie 15
cox narf 10
我的输出是：
Enter filename: lol.out
Printing all edges currently in graph:
(foo, derp) : cost 50
(narf, balls) : cost 30
(foo, balls) : cost 20
(balls, derp) : cost 60
(derp, narf) : cost 40
(derp, cox) : cost 30
(foo, narf) : cost 50
(narf, pie) : cost 99
(cox, pie) : cost 15
(cox, narf) : cost 10
[thread:0] Showing single-source shortest path run for source vertex balls. Format is (start, end) : cost.
(balls, balls : cost 0)
(balls, derp : cost 60)
[thread:0] Showing single-source shortest path run for source vertex cox. Format is (start, end) : cost.
(cox, cox : cost 0)
(cox, narf : cost 10)
[thread:1] Showing single-source shortest path run for source vertex derp. Format is (start, end) : cost.
(derp, derp : cost 0)
(derp, cox : cost 30)
[thread:1] Showing single-source shortest path run for source vertex foo. Format is (start, end) : cost.
(foo, foo : cost 0)
(foo, narf : cost 50)
[thread:2] Showing single-source shortest path run for source vertex narf. Format is (start, end) : cost.
(narf, narf : cost 0)
(narf, cox : cost 10)
[thread:2] Showing single-source shortest path run for source vertex pie. Format is (start, end) : cost.
(pie, pie : cost 0)
(pie, cox : cost 15)
这显然是不正确的——它应该打印从一个顶点到图中每个其他顶点的最短路径，但在这里它只打印到自身的最短路径（始终为 0）以及到其直接相邻的一个的路径邻居。它根本没有遍历图表。然而，最奇怪的部分是取消注释 GraphTest.cpp 末尾附近的那个大块并注释掉文件处理代码，以便将图形数据硬编码到程序中，一切正常：
Printing all edges currently in graph:
(foo, derp) : cost 50
(narf, balls) : cost 30
(foo, balls) : cost 20
(balls, derp) : cost 60
(derp, narf) : cost 40
(derp, cox) : cost 30
(foo, narf) : cost 50
(narf, pie) : cost 99
(cox, pie) : cost 15
(cox, narf) : cost 10
[thread:0] Showing single-source shortest path run for source vertex balls. Format is (start, end) : cost.
(balls, balls : cost 0)
(balls, foo : cost 20)
(balls, narf : cost 30)
(balls, cox : cost 40)
(balls, pie : cost 55)
(balls, derp : cost 60)
[thread:0] Showing single-source shortest path run for source vertex cox. Format is (start, end) : cost.
(cox, cox : cost 0)
(cox, narf : cost 10)
(cox, pie : cost 15)
(cox, derp : cost 30)
(cox, balls : cost 40)
(cox, foo : cost 60)
[thread:1] Showing single-source shortest path run for source vertex derp. Format is (start, end) : cost.
(derp, derp : cost 0)
(derp, cox : cost 30)
(derp, narf : cost 40)
(derp, pie : cost 45)
(derp, foo : cost 50)
(derp, balls : cost 60)
[thread:1] Showing single-source shortest path run for source vertex foo. Format is (start, end) : cost.
(foo, foo : cost 0)
(foo, balls : cost 20)
(foo, derp : cost 50)
(foo, narf : cost 50)
(foo, cox : cost 60)
(foo, pie : cost 75)
[thread:2] Showing single-source shortest path run for source vertex narf. Format is (start, end) : cost.
(narf, narf : cost 0)
(narf, cox : cost 10)
(narf, pie : cost 25)
(narf, balls : cost 30)
(narf, derp : cost 40)
(narf, foo : cost 50)
[thread:2] Showing single-source shortest path run for source vertex pie. Format is (start, end) : cost.
(pie, pie : cost 0)
(pie, cox : cost 15)
(pie, narf : cost 25)
(pie, derp : cost 45)
(pie, balls : cost 55)
(pie, foo : cost 75)
老实说，我不知道这里发生了什么。我唯一能想到的是某处的东西太早超出范围并导致我的图形对象行为异常，但如果这是真的那么两个输出应该是错误的......希望比我更聪明的人可以运行这并帮助我找出问题所在。