[Issue 12708] New: DMD threaded code running slower than single-threaded code

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=12708

          Issue ID: 12708
           Summary: DMD threaded code running slower than single-threaded
                    code
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: regression
          Priority: P1
         Component: DMD
          Assignee: nobody at puremagic.com
          Reporter: atila.neves at gmail.com

The program below runs slower with threads (no "-s" option) than in one thread
(with the "-s" option). The opposite happens when compiling with gdc, which is
the expected behaviour. Found with dmd 2.065 on Arch Linux 64-bit.

import std.parallelism;
import std.getopt;


import std.array;
import std.ascii;
import std.base64;
import std.bigint;
import std.bitmanip;
import std.concurrency;
import std.container;
import std.cstream;


alias TestFunction = void function();

auto getTests(Modules...)() {
    TestFunction[] tests;
    foreach(mod; Modules) {
        foreach(test; __traits(getUnitTests, mod)) {
            tests ~= &test;
        }
    }
    return tests;
}



void main(string[] args) {
    bool single;
    getopt(args,
           "single|s", &single
        );

    enum tests = getTests!(
        std.array,
        std.ascii,
        std.base64,
        std.bigint,
        std.bitmanip,
        std.concurrency,
        std.container,
        std.cstream,
        );

    if(single) {
        foreach(test; tests) {
            test();
        }
    } else {
        foreach(test; tests.parallel) {
            test();
        }
    }
}

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