I am curious about threads on iPhone. Are they easy to establish and to maintain? How does it work on the iPhone? Is it real multithreading?
It's certainly possible to develop on a Windows machine, in fact, my first application was exclusively developed on the old Dell Precision I had at the time :)
There are three routes;
- Install OSx86 (aka iATKOS / Kalyway) on a second partition/disk and dual boot.
- Run Mac OS X Server under VMWare (Mac OS X 10.7 (Lion) onwards, read the update below).
- Use Delphi XE4 and the macincloud service. This is a commercial toolset, but the component and lib support is growing.
The first route requires modifying (or using a pre-modified) image of Leopard that can be installed on a regular PC. This is not as hard as you would think, although your success/effort ratio will depend upon how closely the hardware in your PC matches that in Mac hardware - e.g. if you're running a Core 2 Duo on an Intel Motherboard, with an NVidia graphics card you are laughing. If you're running an AMD machine or something without SSE3 it gets a little more involved.
If you purchase (or already own) a version of Leopard then this is a gray area since the Leopard EULA states you may only run it on an "Apple Labeled" machine. As many point out if you stick an Apple sticker on your PC you're probably covered.
The second option is more costly. The EULA for the workstation version of Leopard prevents it from being run under emulation and as a result, there's no support in VMWare for this. Leopard server, however, CAN be run under emulation and can be used for desktop purposes. Leopard server and VMWare are expensive, however.
If you're interested in option 1) I would suggest starting at Insanelymac and reading the OSx86 sections.
I do think you should consider whether the time you will invest is going to be worth the money you will save though. It was for me because I enjoy tinkering with this type of stuff and I started during the early iPhone betas, months before their App Store became available.
Alternatively, you could pick up a low-spec Mac Mini from eBay. You don't need much horsepower to run the SDK and you can always sell it on later if you decide to stop development or buy a better Mac.
Update: You cannot create a Mac OS X Client virtual machine for OS X 10.6 and earlier. Apple does not allow these Client OSes to be virtualized. With Mac OS X 10.7 (Lion) onwards, Apple has changed its licensing agreement in regards to virtualization. Source: VMWare KnowledgeBase
Updated with Jörg's Sept 2011 comment
You seem to be confusing two very different things here: the Ruby Programming Language and the specific threading model of one specific implementation of the Ruby Programming Language. There are currently around 11 different implementations of the Ruby Programming Language, with very different and unique threading models.
(Unfortunately, only two of those 11 implementations are actually ready for production use, but by the end of the year that number will probably go up to four or five.) (Update: it's now 5: MRI, JRuby, YARV (the interpreter for Ruby 1.9), Rubinius and IronRuby).
The first implementation doesn't actually have a name, which makes it quite awkward to refer to it and is really annoying and confusing. It is most often referred to as "Ruby", which is even more annoying and confusing than having no name, because it leads to endless confusion between the features of the Ruby Programming Language and a particular Ruby Implementation.
It is also sometimes called "MRI" (for "Matz's Ruby Implementation"), CRuby or MatzRuby.
MRI implements Ruby Threads as Green Threads within its interpreter. Unfortunately, it doesn't allow those threads to be scheduled in parallel, they can only run one thread at a time.
However, any number of C Threads (POSIX Threads etc.) can run in parallel to the Ruby Thread, so external C Libraries, or MRI C Extensions that create threads of their own can still run in parallel.
The second implementation is YARV (short for "Yet Another Ruby VM"). YARV implements Ruby Threads as POSIX or Windows NT Threads, however, it uses a Global Interpreter Lock (GIL) to ensure that only one Ruby Thread can actually be scheduled at any one time.
Like MRI, C Threads can actually run parallel to Ruby Threads.
In the future, it is possible, that the GIL might get broken down into more fine-grained locks, thus allowing more and more code to actually run in parallel, but that's so far away, it is not even planned yet.
JRuby implements Ruby Threads as Native Threads, where "Native Threads" in case of the JVM obviously means "JVM Threads". JRuby imposes no additional locking on them. So, whether those threads can actually run in parallel depends on the JVM: some JVMs implement JVM Threads as OS Threads and some as Green Threads. (The mainstream JVMs from Sun/Oracle use exclusively OS threads since JDK 1.3)
IronRuby implements Ruby Threads as Native Threads, where "Native Threads" in case of the CLR obviously means "CLR Threads". IronRuby imposes no additional locking on them, so, they should run in parallel, as long as your CLR supports that.
Rubinius implements Ruby Threads as Green Threads within its Virtual Machine. More precisely: the Rubinius VM exports a very lightweight, very flexible concurrency/parallelism/non-local control-flow construct, called a "Task", and all other concurrency constructs (Threads in this discussion, but also Continuations, Actors and other stuff) are implemented in pure Ruby, using Tasks.
Rubinius can not (currently) schedule Threads in parallel, however, adding that isn't too much of a problem: Rubinius can already run several VM instances in several POSIX Threads in parallel, within one Rubinius process. Since Threads are actually implemented in Ruby, they can, like any other Ruby object, be serialized and sent to a different VM in a different POSIX Thread. (That's the same model the BEAM Erlang VM uses for SMP concurrency. It is already implemented for Rubinius Actors.)
Update: The information about Rubinius in this answer is about the Shotgun VM, which doesn't exist anymore. The "new" C++ VM does not use green threads scheduled across multiple VMs (i.e. Erlang/BEAM style), it uses a more traditional single VM with multiple native OS threads model, just like the one employed by, say, the CLR, Mono, and pretty much every JVM.
MacRuby started out as a port of YARV on top of the Objective-C Runtime and CoreFoundation and Cocoa Frameworks. It has now significantly diverged from YARV, but AFAIK it currently still shares the same Threading Model with YARV. Update: MacRuby depends on apples garbage collector which is declared deprecated and will be removed in later versions of MacOSX, MacRuby is undead.
Cardinal is a Ruby Implementation for the Parrot Virtual Machine. It doesn't implement threads yet, however, when it does, it will probably implement them as Parrot Threads. Update: Cardinal seems very inactive/dead.
MagLev is a Ruby Implementation for the GemStone/S Smalltalk VM. I have no information what threading model GemStone/S uses, what threading model MagLev uses or even if threads are even implemented yet (probably not).
Unfortunately, only two of these 11 Ruby Implementations are actually production-ready: MRI and JRuby.
So, if you want true parallel threads, JRuby is currently your only choice – not that that's a bad one: JRuby is actually faster than MRI, and arguably more stable.
Otherwise, the "classical" Ruby solution is to use processes
instead of threads for parallelism. The Ruby Core Library
Process module with the
method which makes it dead easy to fork off another Ruby
process. Also, the Ruby Standard Library contains the
Distributed Ruby (dRuby / dRb) library, which allows Ruby
code to be trivially distributed across multiple processes, not
only on the same machine but also across the network.
- The difference between a process and a thread
- C# – How to update the GUI from another thread
- Ios – How to sort an NSMutableArray with custom objects in it
- Java – Difference between wait() and sleep()
- Python – How to use threading in Python
- Java – How do servlets work? Instantiation, sessions, shared variables and multithreading
- Ios – Passing data between view controllers
- C++11 introduced a standardized memory model. What does it mean? And how is it going to affect C++ programming