Processes and Isolates

Processes

Fletch supports running multiple processes concurrently. Each of the processes has its own heap and they only interact with other processes through message passing. Fletch can schedule a very large amount of processes across a much smaller set of native threads. Blocking a process does not block the native thread the process is currently executing on. Fletch is currently able to run ~450,000 processes concurrently on a 32-bit machine and schedule them on a number of native threads that match the number of cores in the system.

Here's a simple example that illustrate how to spawn processes in Fletch:

main() {
  for (int i = 0; i < 50000; i++) {
    Process.spawn(fib, 12);
  }
}

int fib(n) {
  if (n <= 1) return 1;
  return fib(n - 1) + fib(n - 2);
}

Isolates

Isolates work at a slightly higher level than processes. The isolate APIs allow programmers to pause, resume, and kill isolates from the outside - and we expect to be able to build this on top of the lower level processes. So far, we haven't implemented support for the dart:isolate library in Fletch yet.