Multithreading on Mac OS X

Question

Level 1

1 points

Multithreading on Mac OS X

I've recently read somewhere on the Web that Mac OS X has no concept of multithreadiing. I'm assuming from this that OS X uses some form of coarse-grained scheduling based on task/process. How does the Java VM run on OS X? Java apps rely on multithreading within the VM.

Thanks.

Windows Vista

Posted on Jun 2, 2009 8:35 AM

Reply

Answer 1

a brody

Level 10

84,771 points

Jun 2, 2009 12:04 PM in response to IPEnthusiast

IPEnthusiast,

When you open the Terminal, you can type

ps -ax

and list all the processes in Mac OS X as individual threads.

When you read the website from Apple Developer, any programmer following Apple's guidelines will make at least Posix compliant threads if not Cocoa. There are naturally some issues with Carbon programming, stated here:

http://www.macintouch.com/m10carbon.html

So as long as you are running all non-legacy code, you should be good to go.

Reply

Answer 2

Jun 2, 2009 12:23 PM in response to IPEnthusiast

IPEnthusiast wrote:
Well, simply because Mac OS X is based on UNIX, it can't be assumed that the OS is multithreaded. Multithreading is a concept that came around way after the first UNIX OSes were developed.

Multithreading is mandated by Posix, and OS X 10.5 is fully Posix compliant. In fact it is UNIX 03 registered, and therefore it is Unix. See Mac OS X Leopard: Technology for more.

If you want to know more about threads in OS X, try

man 3 pthread

And this actually manifested itself in earlier versions of the Linux kernel that simulated threads by actually launching a whole process in place of a thread, to take advantage of the process scheduler. Linux was firmly based on old UNIX code, I believe the implementation was called Minix.

On the other hand, Linux and Minix were, and are, not Unix. Neither were "based on" old Unix code.

Reply

Answer 3

a brody

Level 10

84,771 points

Jun 3, 2009 8:45 AM in response to a brody

I might ammend this post saying, there is a Developer forum where you can ask what Mac OS X does support, or how it supports a certain feature, rather than off the bat assume it does not support it. It is found here:

http://discussions.apple.com/forum.jspa?forumID=727

Additionally you can search the resources at http://developer.apple.com/

I found the above link about Thread Local Storage though with the help of Google.

I would encourage to you dispell any myths you've heard, by asking how to approach a technical issue, instead of saying it does not support XYZ.

Reply

Answer 4

a brody

Level 10

84,771 points

Jun 2, 2009 8:44 AM in response to IPEnthusiast

Mac OS 8 and 9 were multithreading in many tasks, but the application switching was not. Mac OS X offers multithreading at the application level. To see the extent of the threading, your Activity Viewer/Monitor utility (it was renamed with a certain version of Mac OS X) will show you all the separate tasks.

Reply

Answer 5

Courcoul

Level 6

18,594 points

Jun 2, 2009 9:13 AM in response to IPEnthusiast

Since you sound like a knowledgeable programmer, I will assume you have installed or will install soon the Developer Tools package. When that is done, go into the /Developer/Applications/Performance Tools/ folder and run Thread Viewer. You will either attach it to an already-running application or use it to start a new application, after which you will get a window where you can see in real time all the threads being used by the chosen application, down to the specific code being executed. Knock yourself out... 😀

Side note: I'd suggest you register yourself on the [Apple Developer Connection|http://developer.apple.com> (there's a free registration option) so you can download the very latest version of the Developer Tools, as well as many other development goodies.

Reply

Answer 6

Jun 2, 2009 9:15 AM in response to IPEnthusiast

Hi IPEnthusiast;

With OS X being based on Unix, I would have to say that it is multithreaded. It is most certainly more capable of multithreading then anything from M$.

In the years of IT support that I have done, I can't believe how poorly Windows is at multithreading and utilizing multiple CPUs. So many times the customer would for Windows and later we would run Unix on the same server hardware and get significantly better perform simply by migrating off of Windows.

Allan

Reply

Answer 7

Jun 2, 2009 9:28 AM in response to IPEnthusiast

OS X is a fully multithread-aware operating system. The latest version of Java runs on it, and multithreaded java programs and applets are all fully functional, provided they dont require some OS-specific or hardware-specific resource.

Reply

Answer 8

a brody

Level 10

84,771 points

Jun 2, 2009 10:00 AM in response to Topher Kessler

The latest version of Java runs on it,

Not quite true:

http://www.javatester.org/version.html

says the latest version for Mac OS X is:

1.6.0_07-b06-153

Yet

1.6.0_14 is most current. Not that it matters in terms of multithreading, but facts are important.

Reply

Answer 9

varjak paw

Level 10

182,536 points

Jun 2, 2009 10:06 AM in response to a brody

The latest version of Java does run on Mac OS X 10.5. The fact that the latest version is not yet publicly available is a different matter. Just to clarify that it's an issue of release, not technical capability of the OS. As you say, facts are important.

Reply

Answer 10

IPEnthusiast Author

Level 1

1 points

Jun 2, 2009 11:25 AM in response to Allan Eckert

Well, simply because Mac OS X is based on UNIX, it can't be assumed that the OS is multithreaded. Multithreading is a concept that came around way after the first UNIX OSes were developed. And this actually manifested itself in earlier versions of the Linux kernel that simulated threads by actually launching a whole process in place of a thread, to take advantage of the process scheduler. Linux was firmly based on old UNIX code, I believe the implementation was called Minix.

Reply

Answer 11

Jun 2, 2009 11:40 AM in response to IPEnthusiast

Hi IPEnthusiast;

You can have any opinion you want. It doesn't matter to me.

I believe as do the others who have posted in reply to your question that Mac OS X is multithreaded. So unless you can produce some proof the the contrary, I am sticking by my original statement.

Allan

Reply

Answer 12

IPEnthusiast Author

Level 1

1 points

Jun 2, 2009 12:50 PM in response to Allan Eckert

And the robust combination of Windows Server/SQL Server has not figured atop the TPC OLTP benchmark with a poorly designed OS. While SQL Server itself uses its own scheduler, the underlying OS plays a very crucial part in how the database engine performs. Since the introduction of distributed partitioned views in SQL Server 2000, Microsoft has consistently blown the top off of the TPC benchmark. You just have to know how to tune these products.

Reply

Answer 13

Jun 2, 2009 8:19 PM in response to IPEnthusiast

Hi IPEnthusiast;

And your point is???

Like any of us really care two cents about anything at all from Microsloth here.

Personally Winders can fall of the edge of the world and I would not care in the least.

Allan

Reply

Answer 14

IPEnthusiast Author

Level 1

1 points

Jun 3, 2009 6:56 AM in response to Allan Eckert

Actually, what OS X does not support is Thread Local Storage. At the extremity, if you need to spin off a bunch of threads that are based on the same function/method and if you don't have any need to share state between those threads, TLS simply makes each thread look like an independent method. But sharing state is the more common scenario in multithreading, so the OS can lend a very helping hand through its implementation of TLS there as well.

Reply

Answer 15

Jun 2, 2009 8:42 AM in response to IPEnthusiast

Don't know where you got your information from, but Apple operating systems have been multithreaded since at least OS 8.

Reply

Quick Links

Multithreading on Mac OS X