lightweight-processes

I found an answer to the question here . But I don't understand some ideas in the answer. For instance, lightweight process is said to share its logical address space with other processes. What does it mean? I can understand the same situation with 2 threads: both of them share one address space, so both of them can read any variables from bss segment (for example). But we've got a lot of different processes with different bss sections and I dunno how to share all of them. From MSDN, Threads and Processes : Processes exist in the operating system and correspond to what users see as programs or

I've been reading the "Real World Haskell" book, the chapter on concurrency and parallelism. My question is as follows: Since Haskell threads are really just multiple "virtual" threads inside one "real" OS-thread, does this mean that creating a lot of them (like 1000) will not have a drastic impact on performance? I.e., can we say that the overhead incurred from creating a Haskell thread with forkIO is (almost) negligible? Please bring pactical examples if possible. Doesn't the concept of lightweight threads prevent us from using the benefints of multicore architectures? As I understand, it is

Erlang's Characteristics From Erlang Programming (2009): Erlang concurrency is fast and scalable. Its processes are lightweight in that the Erlang virtual machine does not create an OS thread for every created process. They are created, scheduled, and handled in the VM, independent of underlying operating system. As a result, process creation time is of the order of microseconds and independent of the number of concurrently existing processes. Compare this with Java and C#, where for every process an underlying OS thread is created: you will get some very competitive comparisons, with Erlang