Talk:Thread (computing)

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Computing (Rated Start-class)
WikiProject icon This article is within the scope of WikiProject Computing, a collaborative effort to improve the coverage of computers, computing, and information technology on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 ???  This article has not yet received a rating on the project's importance scale.
WikiProject Computer science (Rated Start-class, Mid-importance)
WikiProject icon This article is within the scope of WikiProject Computer science, a collaborative effort to improve the coverage of Computer science related articles on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 Mid  This article has been rated as Mid-importance on the project's importance scale.


substitute "the smallest" with "a" confidence level 5/10 — Preceding unsigned comment added by (talk) 04:15, 29 April 2013 (UTC)


Thanks for fleshing out the stub, Lee. I knew this stuff, but it wasn't on the tip of my tongue (one step further buried in the memory banks). User:Ed Poor


Just for note. I renamed the article to thread (computer science) because threading not necessarily only in software enginnering. -- Taku 16:14, Mar 28, 2004 (UTC)

Process creation cost[edit]

From the article:

"Systems like Windows NT, OS/2 and Linux (2.5 kernel or higher) are said to have "cheap" threads and "expensive" processes, while in other systems there is not so big a difference."

Eh? I though one major advantage of Linux was its relatively low process creation cost, and the new NPTL implementation of Linux threads is a 1:1 implementation where there is little difference between a thread and a process at the lowest level. -- The Anome 22:33, 22 Oct 2004 (UTC)

If you take a look at NetBSD 2.x or DragonFly BSD you will notice that they don't use 1:1, but instead N:M, which is a lot more efficient than Linux 1:1. I've added a link about NetBSD SA (Scheduler Activations) in this page that I advise you to look at. -- RuiPaulo 23:54, 24 Oct 2004 (UTC)


The section titled "Processes, Threads, and Fibers" and its subsections were started by Daniel Barbalace.


Thanks for the excellent work, Daniel. -- The Anome 14:59, 24 Oct 2004 (UTC)

System call for a context switch?[edit]

The article says "Typically fibers are implemented entirely in userspace. As a result, context switching between fibers in a process is extremely efficient: because the kernel is oblivious to the existence of fibers, a context switch does not require a system call." Why would a context switch require a system call in any situation? Is it talking about non-preemptive multitasking? If so, wouldn't it be better if the article mentioned it? If the article isn't intended to say that a system call is required for a context switch, then it would be better if it were cleared up in the article. It's misleading. It would help if the article (that section) is clearer anyway.

Yeah, it would be more clear to say "a context switch does not require a kernel entry" or some such. I'm not sure that it matters whether or not the thread implementation is preemptively scheduled or not: in a cooperatively scheduled implementation of kernel threads, there is still some kernel state associated with the currently-running thread, and so a kernel entry is some kind is required to switch that state, right? The point is somewhat academic, anyway, as cooperatively-scheduled kernel thread implementations are rare AFAIK. Neilc 04:23, 20 Jun 2005 (UTC)
I made that change. I was trying to figure out how to get something about pre-emptive scheduling of threads involving the kernel programming a hardware interrupt in order to stop the current thread, but couldn't figure out how to word that decently. :) Dianne Hackborn 05:51, 22 Jun 2005 (UTC)

Multiprocess vs. Multithreaded vs. Fibers[edit]

Would anyone mind if I did some cleanup of this table? It seems to me that all the long discussion about particular systems (especially the big one on AmigaOS) hides the comparison it is trying to make. What about moving discussion about specific operating systems to a section below?

Also, I kind-of disagree with the definition of multiprocess that is being implied here -- that it means something about more than one user-level "application" running. I think it should be much more tied to the idea of memory protection: that is, an OS with memory protection has multiple processes. From this perspective, for example, the traditional AmigaOS (pre-PPC) would be better classified as multi-threaded only, and would serve as a good example to illustrate the difference between that and processes.

Anyway, I don't want to step on anyone's toes. :)

Dianne Hackborn

Sounds good to me. Be bold! :) Neilc 05:00, 20 Jun 2005 (UTC)
Also, I want to say that the text in the table is really hard to read; not everyone has a big display. -- Taku 05:59, Jun 20, 2005 (UTC)

table changes[edit]

Personally I like the old table format more -- the new format is too compact and is difficult to read. Neilc 00:48, 23 Jun 2005 (UTC)

Okay, I made another attempt. What do you think? Dianne Hackborn 02:59, 23 Jun 2005 (UTC)
I noticed that "modern" operating systems (second-to-last row in the chart) are marked as supporting multiprocessing, multithreading but not fibers (Y Y N), but then it says that nearly all operating systems after 1995 support all three (Y Y Y). This seems to be self-contradictory; for example, Mac OS X is a modern operating system, and also (if I remember correctly) came out after 1995. Does it fall in the second-to-last category (supporting multiprocessing, multithreading but not fibers), or does it fall in the last category (supporting all three)? 04:14, 9 July 2006 (UTC)
Why is the fibers colomn even in this table? By definition, fibers can be implemented in a user program and thus don't rely on the existance of either threads or processes (so one could, say, implement them in DOS). I personally think the fibers column should be removed from the table entirely or changed to all Y letters. --NotQuiteEXPComplete 12:40, 14 July 2006 (UTC)
Indeed, some programming languages (those with coroutines or continuations) support "fibers" out of the box, with little effort. In other languages (like C), it requires some systems-level wizardry, but such can be hidden behind a library. About the only use of the fibers column is documenting which OS's provide API calls in the standard library; I can't think of any modern systems which do not. --EngineerScotty 23:30, 18 July 2006 (UTC)
Why is Microsoft Windows listed as "Y Y N"? There are native functions to create and schedule fibers (CreateFiber, ConvertThreadToFiber,SwitchToFiber), contained within kernel32.dll, and supported since Win9x. Goffrie 16:54, 20 July 2006 (UTC)

threads vs processes[edit]

Not always are processes provided only by operating system. Erlang programming language has support for processes in language - they are completely isolated from one another (while running within single OS process). Pavel Vozenilek 22:02, 29 July 2005 (UTC)

The question is, are these truly "processes" if not provided by the operating system? For instance .NET provides AppDomains that are very "process-like", but are not true processes. That is to say that the AppDomains provide memory isolation, context, and fault tolerance (in that it can be unloaded or ab-end without affecting other appdomains in the system). These are still not considered processes, however, because they still run in the same (although isolated) address space as the rest of the process. Is this the same thing with Erlang? Being that I've never worked with it at all, I couldn't make a valid argument one way or another. - Sleepnomore 15:53, August 26, 2005 (UTC)


I've added Three .NET threading resources - two of these are admittedly my own published works. I've added them only because there were no other .NET programming resources listed. Feel free to remove them if you feel they are inappropriate. Both of these books are out of print but you can still find them quite often at book stores and from secondary book stores. I have a fourth book published that is still on the market that I didn't list because it covers two other areas as well as threading. The title is Pro .Net 1. 1 Remoting, Reflection, and Threading and the ISBN is 1-590-59452-5. While it is more "current", the fact that it covers two other topics doesn't seem to make it appropriate for this article. Once again, feel free to add it if you feel otherwise. - Sleepnomore 15:46, August 26, 2005 (UTC)

Fiber, Fiber, Fiber?[edit]

Huh? Well, I'm no thread expert but I've never heard this term in this context before. Furthermore, it's spread all over the article, so one would think it's something widely known and used. However, when I search on the web, all I find is that it seems to be some seemingly unpopular concept used by Windows NT. It seems to be what I'd call user-level (or userland) threads e.g. GNU Pth or maybe it refers to anything thread-alike as used in programs with a main-loop which delegates/schedules short-lived tasks using state machines? So is "fiber" common terminology or just some marketing resp. product-specific term? -- 05:01, 4 December 2005 (UTC)

The fiber term seems to me very specific to the NT world indeed. The current article tends to say that user-level threads would be called fibers, but that is wrong: there are N:M user-level implementation of "threads" which are really threads, like PM2's Marcel library: they can be preempted, are scheduled by the library's scheduler, etc. They really behave like POSIX threads from the point of view of the application. The "fiber" concept introduced by NT is quite different: it's more about the application managing contextes. That could be compared to POSIX's makecontext/swapcontext. If nobody objects, I'd rather reword the whole page to fix the confusion between user-level threads and fibers. SamuelThibault 15:57, 1 December 2008 (UTC)
Fibers could also be compared with what a lot of programming environment implement: tasks SamuelThibault 15:59, 1 December 2008 (UTC)

Threads are also used by web servers[edit]

Many web servers use threads somehow, sure. However, I find those two paragraphs not very useful. In my opinion, it gives the wrong idea that either multi-threading or multi-processing is necessary for web servers and similar kind of servers in general. That's far from the truth. At least on single-CPU machines an approach using select, poll, kevent, epoll etc. is usually far more efficient and also a fairly popular approach for all kinds of servers at least in C/C++. Even in Java using tons of threads does not seem to scale very well and using non-blocking I/O instead is actually better even if the naive approach of one thread per connection - or in C/C++ even one process per connection (resp. client) - is easier to code.

The part about Apache 1.3 using multi-processing almost qualifies as FUD. At the very least a lot of context or explanations are missing and most of those "dangers" apply to multi-threading equivalently. In short, I think the article was better without those two paragraphs. -- 05:14, 4 December 2005 (UTC)

You should get more informed before calling this FUD. Personally having extensive server-side programming experience, I can say that depending on the application, one of the following is a best approach: 1) single threaded, single process, using non-blocking I/O (i.e. an IRCd, where many memory needs to be shared among clients without the overhead of locks, and without need for any CPU intensive tasks or expensive system calls other than non-blocking I/O) 2) multiple processes using a pool of processes (ideal when you need very solid production quality, avoiding memory leaks of system libraries, avoiding a client from crashing the whole application, using processes of various credentials, avoiding thread-related issues if the application is non-trivial and a fair number of syscalls and processing is needed to serve the clients. 3) a multithreaded approach, which is prone to some of the problems of (1), but is more powerful and can allow more processing to be done to serve a client, but without some obvious security protections of (2) (at least if not also using multiple processes). I had to program applications using all of these models. For every situation, one model is clearly superior over the others, these are not merely style or paradigm programming issues. Of course, this doesn't mean that you can't appropriately use both multiple processes and threads in an application. You just can't in any sanity avoid using multiple processes for some applications.
It should also be noted that the launching time of processes or threads is a less important factor (because pools can be used, and because process creation is usually light enough on modern OSs using Copy-on-write) than a) the stability/security implications, b) frequency of shared resources access and c) type of processing needed, which will generally define which of the models an application should ideally use. Also note that systems with Symmetric multiprocessing permit both multiple processes and multiple threads to utilize more than a single processor.
Back on topic with Apache and PHP, it took a fair amount of time for PHP to decently run under Apache 2 in multithreaded mode, and depending on the PHP extensions and OS you're using, you can still experience issues. This is partly caused by the fact that many libraries expect to run under a normal process and use blocking or process-wide affecting system calls, and most PHP extensions just map to those library calls. As for the OS-specifics, despite the POSIX thread standard, which defines a widely spread API, implementations widely vary. There shouldn't be much issues if on your particular operating system every system call is thread-friendly, and its C library uses all the necessary hacks to mutex-wrap thread-unfriendly functions (other than security/stability/memory leaks issues solved by multiple processes). The PHP wrappers can also limit problems lock-wrapping calls made to a non-reentrant C function (loosing the concurrency adventage of threads when using this function of course). Also, weither using threads provides greater concurrency than processes also depends on your OS and the thread's implementation.
A few real-world examples of implementation specifics: some of my own multithreaded applications couldn't properly run under LinuxThreads (while ran fine under Solaris and NetBSD) because LinuxThreads wasn't up to the POSIX standard, other than providing a compatible API). These now run fine under Linux 2.6 with the Native POSIX Thread Library. Still today, however, a number of people decide to keep 2.4 on their production servers for stability considerations. Another example, several years back, on NetBSD it was only possible to use user-space threads (what some call fibers), through the GNU PTh library, unproven-threads or unreal-threads libraries. Under these libraries, some system calls had to be avoided alltogether to avoid problems, and heavy processing loops had to be done in a separate process, or to explicitely yield control frequently back to the thread scheduler voluntarily, because these particular implementations did not use a preemptive scheduler (not worthwhile to provide without special kernel support). Another aspect is that POSIX did not properly define a relation between threads and the standard I/O subsystems of unix systems using file desriptors. For instance, while a thread may wait into select(2) or poll(2), it cannot at the same time use a more efficient mode of inter-thread messages based on shared memory queues and notification through conditional variables, without some hackery, like dedicating a thread to file descriptor polling and having that thread communicate in a thread-efficient manner with other threads of the process. Therefore, if your application heavily relies on interprocess communication because of a need like privilege separation, is using threads still worth it considering the hassle it adds? (an implementation of a test project I wrote to fusion inter-thread messages and file descriptor polling can be found at [1] (does not work with LinuxThreads or PTh). I am certain that there are many other examples and that many programmers can relate. As an ending note, interestingly, the Apache 1.3 branch isn't about to die, and is still being actively maintained and used worldwide. The very powerful Postgresql database also benefits from multiple processes, and there have been heated discussions about the process vs thread models between its community and that of MySQL. MySQL uses a MySQL_safe process which role is to restart the crashing main MySQL multithreaded process (not that it crashes often in my personal experience, though :) but an example where an extra process was required.
This was a lengthy reply, but points which are worthwhile to consider. I'll leave for others to relate and if necessary update the article if they consider it useful. It's probably sufficient to keep these notes on this discussion page, though. -- 03:36, 3 March 2006 (UTC)
I think all your questions are answered in the Process, Thread, Fiber Table that was deleted. Why the hell was that table deleted? It was the most useful part of the article.


A while ago I changed the example to a C# example that I believed showed purely the concept of multi-threading more clearly than our current example which would be more suited to Algorithms For Prime Number Generation ;) I just feel that the example should be very closely tied to threading as opposed to having an exterior purpose. Here is the reverted example I propsed before: [2] Any thoughts? Martin Hinks 17:43, 29 January 2006 (UTC)

The commentary pertaining to the example says, "of course, this problem [the race condition] is easily corrected using standard programming techniques" raises the question: How? 04:17, 9 July 2006 (UTC)

Getting It Str8[edit]

Ey people, i'm kind of a newbie to CPU's. The terminology used in this article (and most wikipedia articles) is kind of complex. So, i'm wondering if someone can tell me a little about it in plain english like;

1) What exactly are Threads, what do they do, and how do they work?

2) What is the difference between a thread, process, and the other thing?

3) What exactly does a kernel do? Is it embedded in an Operating System? Why 'Linux Kernel' and not just 'Linux'?

4) Tell me some other things i should know about this stuff please.

Any help would be greatly appreciated and if you do help me, ill make it worth a lot of other people's time by editing this main article into simpler words. Thanks. KittenKiller

It seems to me that the terminology used in most computer science wikipedia articles is kind of complex. However, the same cannot be said for most wikipedia articles. Care to comment? 04:21, 9 July 2006 (UTC)


"""while in other operating systems there is not so big a difference"""
What exactly are the other operating systems? Linux, BeOS. It's nice to be specific.
Probably most other commonly used operating systems, those that I know well being all of the BSDs, Linux, Solaris, MacOS (I did not use BeOS, but it well might be using COW (Copy-on-write) in fork(2) to avoid actually creating all pages of a newly created process too). I would not be surprised if IRIX, HPUX, Tru64 also do, but someone who knows should confirm this. -- 09:54, 3 March 2006 (UTC)

process--thread--fiber interrelation[edit]

The concept of a process, thread, and fiber are interrelated by a sense of "ownership" and of containment. .... A fiber can be scheduled to run in any thread in the same process.

There seems a contradiction. If a fiber can be run in any thread, then it's not cointained within any specific thread, nor owned by any specific thread. --tyomitch 15:25, 8 May 2006 (UTC)

For context enrichment, could be nice to add some thread history (OS related, but makes sense also into this context). --User:faragon 12:52, 7 Jun 2006 (GMT+1)

Fibers and NPOV[edit]

Yeah, this whole Fiber stuff needs rewriting, the term is not used for much outside of the NTcentric world. Also curious is the table. What the hell is the last entry? It says most OSs since 1995 use a proces/thread/fiber model. But above it, it says that OS X Win 2k etc (Major OSes released AFTER 1995) use a process/thread model. What came in 1995? Win95?? What about NT (released 93) or Macs which were stuck with classic MacOS (system 7, I believe) until OSX. Seems a little Windowscentric. So much for NPOV! —The preceding unsigned comment was added by (talkcontribs) 23:37, 15 June 2006 (UTC1)


I don't see around here (The referenced talk page) who added the {{contradict}} tag, and more to the point, why? 03:40, 18 July 2006 (UTC)

The tag appears to have been added in this edit by an anon user. If there's no obvious reason for it (and I don't see one) then I suggest we just remove the tag. --Allan McInnes (talk) 05:11, 18 July 2006 (UTC)
They are right though. The table is, in some cases, blatently wrong. Since fibers seem to be just a Windows name for userspace threads from what I can gather, it does appear to be wrong since one should be able to implement them in all of these systems in userspace or one's program. --NotQuiteEXPComplete 17:39, 18 July 2006 (UTC)
Ok. But wrong isn't the same as self-contradictory, which is think what caused some confusion. Nor did the person who did the tagging explicate their reasons here on the talk page, as they were supposed - was there a reason for the tagging, or was it just idle vandalism? If the table's wrong, then by all means fix it (personally I'd be in favor of cutting it completely, since I don't think it adds much value). --Allan McInnes (talk) 18:40, 18 July 2006 (UTC)
I think the contradiction is pointed out under the "Fibers and NPOV" header in the talk page. The last row of the table says "Almost all operating systems after 1995 fall into this category." but many operating systems after 95' are mentioned in previous rows. Maybe not completely self-contradictory, but at least confusing. And I agree with the people that think we should get rid of all this fiver stuff which makes no sense outside NT-land. --Lost Goblin 08:28, 19 July 2006 (UTC)
Yeah, I'm going to go ahead and kill the table. --NotQuiteEXPComplete 19:17, 26 July 2006 (UTC)

Article restructuring[edit]

Forgive me if this is a poorly stated ... I'm rather tired. I think a good restucturing would go a long way to improving this article. The section headers are also inapropriate in some places were the discussion strays from what the section header talks about. In general, I think there should be sections comparing (or at least saying a small amount before linking to another article) the entire spectrum of: (1) implementation: kernel-space vs. user-space, (2) for kernel space, the model for interfacing kernel-threads and user-threads: many-to-one, one-to-one, one-to-many, (3) co-operitve scheduling (i.e. by the process) vs. premptive sceduling (i.e. by the kernel) and showing how the desireable properties of threads, namely continuing to execute the process in the face of blocking calls and being able to run on multiprocessor machines, pretty much follow directly from these three things. The article mentions most of this stuff, but the flow and cohesiveness is pretty poor.--NotQuiteEXPComplete 06:46, 9 August 2006 (UTC)

Green threads[edit]

I don't think "green threads" came from SunOS. Instead, I think they came from the Green project:

Calling user-level threads "green threads" probably resulted from the early Java JDK using that name for the thread implementation inherited from the Green project.

Booskunk 06:53, 23 October 2006 (UTC)

Multithreaded programming in dual vs quad+ cores[edit]

Someone please address the issue of multithreaded programming in dual vs quad+ cores. Nowhere does it talk about whether or not it is more difficult for the programmer to create a program to take advantage of >2 processors. We understand from the article that you must write the application with multiple threads in mind BUT nowhere does it talk about the issue of programming difficulty or lake thereof for >2 processors.

Basically: Will a multithreaded program of today have to be modified for a computer with 4, 8, 32 cpus?

—The preceding unsigned comment was added by (talkcontribs) 10:54, 8 November 2006 (UTC)

In many cases, not if it's coded intelegently. See thread pool. Howerver, I think there are algorithms that only admit so much parallelization, so sometimes, it may only be possible to parallelize something so much.--NotQuiteEXPComplete 10:08, 20 June 2007 (UTC)
Correct, see Amdahl's Law. Regarding the question: it depends. If you are using multithreading as means to parallelize an algorithm (as opposed to using multiple machines with single CPUs via MPI) then you will have to adjust your algorithm for caching, shared memory, etc. If you're creating something to distribute workload (like a web server) then it shouldn't matter much how many processors you have since each request is essentially independent. Cburnett 12:54, 20 June 2007 (UTC)

Language error[edit]

Some sentences in the introduction do not seem to make grammatical sense:

"On a multiprocessor or multi-core system, which are beginning into general use, threading can be achieved via multiprocessing, wherein different threads and processes can run literally simultaneously on different processors or cores."

Should be replaced with something like "which are beginning to see general use"

Also "Absent that, programs can still implement threading by using timer..." is wrong. 11:27, 23 January 2007 (UTC)

Yes. Feel free to fix it. –EdC 12:00, 23 January 2007 (UTC)

C example[edit]

Can someone please provide an example in C? --Pradeep.v 06:43, 7 April 2007 (UTC)


Can someone add an explanation for 1×1, M×N, 1×M or 1:1, M:N, 1:M or whatever... —The preceding unsigned comment was added by Frap (talkcontribs) 21:26, 26 April 2007 (UTC).

I believe that the usage with a colon indicates whether there is a 1:1 correspondence between (user space) "threads" and (kernel space) lightweight processes. On OSes where LWPs are expensive, it can make sense for the language or threading library to create more "threads" than there are LWPs backing them, and juggle them as threads enter wait states. So M:1 indicates that there are M fibers per thread (LWP), while M:N indicates a situation where the process as a whole has N LWPs backing M fibers (where M > N). Evidently, in the latter case at most M fibers can be running concurrently - I suppose the rest must be yielded or (perhaps) engaged in simulated blocking I/O. Try this link: Understanding Threads. –EdC 20:11, 27 April 2007 (UTC)

Ambiguity in para 2.[edit]

Para 2 starts "Multiple threads can be executed in parallel on many computer systems."

I believe you mean this in the sense of: On many computer systems, multiple threads can be executed in parallel on a single processor.

and are not refering to multiprocessing. However the existing sentence can be read either way. —Preceding unsigned comment added by (talk) 23:19, 26 March 2008 (UTC)

Deleted it. Cburnett (talk) 23:24, 26 March 2008 (UTC)

Fiber performance[edit]

"Fibers are an even lighter unit of scheduling which are cooperatively scheduled: a running fiber must explicitly "yield" to allow another fiber to run"


"which makes their implementation much easier than kernel or user threads"

This is a little ambiguous to me. By reading the rest of the section I undestand that it means that it is easier for the OS to implement fibers when compared to threads. But at first I thought it meant that it was easier for the application programmer to use fibers instead of threads, which is not true. Threads are easier because you don't have to worry about scheduling.

"A fiber can be scheduled to run in any thread in the same process."

I don't think so. A fiber can only be scheduled to run in the thread that created it. You can however switch to a fiber that was created by a different thread, but still the fiber will run in the thread that created it.

"This permits applications to gain performance improvements by managing scheduling themselves, instead of relying on the kernel scheduler (which may not be tuned for the application)."

How can you get performance improvement by using fibers? Fibers can't run concurrently (unless they are fibers from different threads). If a fiber makes a blocking call, it won't be able to switch to another fiber until the call unblocks. If you have a single process and thread, just adding fibers won't improve performance.

"Parallel programming environments such as OpenMP typically implement their tasks through fibers."

OpenMP uses fibers? It must also use threads/processes or it wouldn't be able to use multiple processors/cores. Citation, please.

Check this out:

"In general, fibers do not provide advantages over a well-designed multithreaded application."

"From a system standpoint, a fiber assumes the identity of the thread that created it. For example, if a fiber accesses thread local storage (TLS), it is accessing the TLS of the thread that created it. In addition, if a fiber calls the ExitThread function, the thread that created it exits."

"You can call SwitchToFiber with the address of a fiber created by a different thread. To do this, you must have the address returned to the other thread when it called CreateFiber and you must use proper synchronization."

Italo Tasso (talk) 10:42, 9 January 2010 (UTC)

I agree. Fibers alone simply do not run in parallel and OpenMP is intended to exploit parallel systems. Intel is a prominent contributor/supported of the OpenMP project and a paragraph on this Intel page seems to cast further doubt on the connection: "In the Win32 threading API, there is a threading option called fibers that enables users to write their own thread scheduler and so exert fine-grained control over threading operations. This too is not possible in OpenMP."

JohnMcF (talk) 17:46, 11 February 2012 (UTC)

Thread join redirects here, but isn't mentioned in the article[edit]

Thread join, which is wiki-linked from some other synchronization articles, redirects to this article, but the article never mentions joining threads. I think it would be useful to have an explanation of that technique -- it would certainly have helped me. Npdoty (talk) 03:10, 29 April 2010 (UTC)

Daemon thread[edit]

Daemon threads are not mentioned in the article.--Wisamzaqoot (talk) 22:49, 8 October 2011 (UTC)


Recently there were attempts to insert sample of "how to create thread in Java" into this article. Personally, I don't think it belongs to this article (if providing only a sample of creating thread, and only in Java, it is pretty much useless for the article, and if going into all thread-related functions for all languages/OSs, it will become unmanageable), and also it is IMHO a borderline WP:NOTHOWTO, so I've removed the sample, but if there are arguments for including such samples - let's discuss them. If it would be an article about a feature of the programming language - it would be a different story, but for features which can be adequately explained without referring to specifics of the language - IMHO it is unnecessary to introduce such samples. Ipsign (talk) 07:27, 14 September 2011 (UTC)


As a reader, a history section would be useful here. Who first proposed the concept? Who first implemented it? — Preceding unsigned comment added by (talk) 06:48, 17 November 2011 (UTC)

Absolutely agree. When I started off big systems had processes, and little ones didn't. Unix had fork() which created processes. Then I went off into Windows-only for a few years, and while I was there threads got invented as a concept. They'd always been there of course - except that a process was a VM with a single thread. — Preceding unsigned comment added by Number774 (talkcontribs) 10:36, 18 November 2013 (UTC)

Analogy with cooking[edit]

The text mentions an analogy, namely:

To give an analogy, multiple threads in a process are like multiple cooks reading off the same cook book and following its instructions, not necessarily from the same page.

Would the next one be better to clarify the differences between multithreading and multitasking?

To give an analogy, multiple threads in a process are like multiple cooks reading off the same cook book, sharing their ingredients and following its instructions (not necessarily from the same page). Multitasking would be multiple cooks reading off their own cook book and each one has with its own ingredients.

What do you think? --Mattias.Campe (talk) 11:21, 16 April 2012 (UTC)

Missing word ?[edit]

In the article "Thread (computing)" -

There may be a word missing. Reference the third paragraph from the top...

Original... Many modern operating systems directly support both time-sliced and multiprocessor threading with a process scheduler. The kernel of an operating system allows programmers to manipulate threads via the system call interface. Some implementations are called a kernel thread, whereas a lightweight process (LWP) is a specific type of kernel thread that shares the same state and information. (This last sentence does not make sense. "... shares the same and information with what?")

Looks like the last fragment (quotation), which may actually be an editorial comment, is missing the word "state" after the word "same". It also mistakenly ends the quotation after "with what" which is NOT part of the original statement. (talk) 15:00, 5 September 2012 (UTC)

Event-driven programming and Verilog[edit]

Could somebody with expertise clarify/elaborate this final part? It's not clear to me in this context what application-level event-driven programming and hardware description languages like Verilog have to do with threading in general, or with each other.

Skwuent (talk) 01:33, 13 August 2014 (UTC)