d的GC.free用法效果.

version=FREE;//快些,内存很少
version=COLLECT;//慢,但内存为0
import std.stdio;
import std.datetime.stopwatch;
import core.memory;
immutable int[] intZ = [1,2,3,4,4,6,6,8,8,65,8,23,76,2,57,264,23,4,4,6,6,8,8,65,8,23,76,2,57,264,23,4,4,6,6,8,8,65,8,23,76,2,57,264,23,4,4,6,6,8,8,65,8,23,76,2,57,264,23,4,4,6,6,8,8,65,8,23,76,2,57,264,23,4,4,6,6,8,8,65,8,23,76,2,57,264,23,4,4,6,6,8,8,65,8,23,76,2,57,264,23,4,4,6,6,8,8,65,8,23,76,2,57,264,23,4,4,6,6,8,8,65,8,23,76,2,57,264,23];
void main() {
    writeln(GC.stats);
    enum max = 100000;
    StopWatch sw;
    sw.start();
    foreach (i; 0 .. max) {
        bool doprint = !(i % (max/10));
        int[] z = intZ.dup;
        if (doprint) writef("%7d  ", GC.stats.usedSize);
        version(FREE) GC.free(cast(void*) z.ptr);
        version(COLLECT) GC.collect();
        if (doprint) writefln("%7d", GC.stats.usedSize);
    }
    sw.stop();
    writefln("Elapsed: %d ms", sw.peek.total!"msecs");
}

超时:

import std.concurrency;
import std.stdio;
import std.exception;
import core.thread;

//
// version = doTimeout;

void compute(int i) {
  version (doTimeout) {//注释掉时没问题
    writeln("The thread is napping.");
    Thread.sleep(2.seconds);
  }//未注释超时,则崩溃了.
  ownerTid.send(i + 1);
}

void main() {
  auto worker = spawn(&compute, 42);
  const received = receiveTimeout(
    1.seconds,
    (int result) {
      writefln!"收到: %s"(result);
    }
  );

  enforce(received, "超时");
}
//或者下面
import std.concurrency;
import std.stdio;
import std.exception;
import core.thread;

// Uncomment to see what happens upon time out.
version = doTimeout;

struct Done {
}

void computer() {
  bool done = false;
  while (!done) {
    receive(
      (Done _) {
        done = true;
      },

      (int i) {
        version (doTimeout) {
          writeln("The thread is napping.");
          Thread.sleep(2.seconds);
        }
        ownerTid.send(i + 1);
      }
    );
  }
}

void main() {
  // This time we use spawnLinked() so that we will receive
  // a LinkTerminated message. And the name is different and
  // the argument will be passed later with send().
  auto worker = spawnLinked(&computer);

  foreach (i; 0 .. 10) {
    worker.send(i);
    const received = receiveTimeout(
      1.seconds,
      (int result) {
        writefln!"Received the result: %s"(result);
      }
    );

    enforce(received, "Timed out.");
  }

  // Tell worker to stop.
  worker.send(Done());

  // Wait for worker to terminate.
  receiveOnly!LinkTerminated();
}