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Function `std.parallelism.TaskPool.workerIndex`

Gets the index of the current thread relative to this TaskPool. Any thread not in this pool will receive an index of 0. The worker threads in this pool receive unique indices of 1 through this.size.


						
				ulong workerIndex() nothrow @property @safe const;

This function is useful for maintaining worker-local resources.

Example

// Execute a loop that computes the greatest common
// divisor of every number from 0 through 999 with
// 42 in parallel.  Write the results out to
// a set of files, one for each thread.  This allows
// results to be written out without any synchronization.

import std.conv, std.range, std.numeric, std.stdio;

void main()
{
    auto filesHandles = new File[taskPool.size + 1];
    scope(exit) {
        foreach (ref handle; fileHandles)
        {
            handle.close();
        }
    }

    foreach (i, ref handle; fileHandles)
    {
        handle = File("workerResults" ~ to!string(i) ~ ".txt");
    }

    foreach (num; parallel(iota(1_000)))
    {
        auto outHandle = fileHandles[taskPool.workerIndex];
        outHandle.writeln(num, '\t', gcd(num, 42));
    }
}

Authors

License

Boost License 1.0