September 16, 2012 std.parallelism and map questions | ||||
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std.parallelism uses the foreach loop for parallel(). As such, how might I implement a parallel while-loop? Can I use an ordinary for-loop with parallel()? Also, how can I map array elements with a conditional like if()? |
September 16, 2012 Re: std.parallelism and map questions | ||||
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Posted in reply to freeman | On 09/15/2012 08:12 PM, freeman wrote: > std.parallelism uses the foreach loop for parallel(). As such, > how might I implement a parallel while-loop? That doesn't sound right to me because the while loop condition is normally a result of the operations inside the loop itself. And that's a race condition, violating a fundamental rule of parallelism that the operations are indepentent (having no side-effects). Perhaps I am wrong; then I would like to learn about the answer. > Can I use an > ordinary for-loop with parallel()? I think this works: import std.stdio; import std.parallelism; import core.thread; void foo(size_t i) { writefln("Working on %s", i); Thread.sleep(dur!("msecs")(500)); } void main() { auto workers = new TaskPool(2); for (size_t i = 0; i != 10; ++i) { if (i != 7) { auto t = task!foo(i); workers.put(t); } } workers.finish(); } > Also, how can I map array elements with a conditional like if()? You can pass the return range of std.algorithm.filter to map: import std.stdio; import std.parallelism; import std.range; import std.algorithm; int tenTimes(int i) { return i * 10; } void main() { auto result = taskPool.map!tenTimes(iota(10).filter!(a => a % 2)(), 5); writeln(result); } Ali |
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