Talk:Thread (computing)

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Untitled

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

Renaming

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

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)

Authors

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

Website: http://www.clearthought.info

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

System call for a context switch?

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)

Books

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)

Windows services and processes

Could you explain what category MS Windows Services fit into this? I've seen descriptions of Windows services as "processes" themselves.

I take it that in Windows Task Manager, what are described as "Services" are actually processes in general computing lexicon, and Task Manager's "Processes" are ?super-processes or programs. "Threads" as such are not displayed in Task Manager (understandably - a too low level of detail outside of technical work/debugging).

If I'm wrong about this, then I'm clearly more confused than I thought! — Preceding unsigned comment added by 80.189.81.20 (talk) 13:11, 3 July 2019 (UTC)

To quote "Service Programs" in Microsoft's documentation:

A service program contains executable code for one or more services. A service program created with the type SERVICE_WIN32_OWN_PROCESS contains the code for only one service. A service program created with the type SERVICE_WIN32_SHARE_PROCESS contains code for more than one service, enabling them to share code. An example of a service program that does this is the generic service host process, Svchost.exe, which hosts internal Windows services. Note that Svchost.exe is reserved for use by the operating system and should not be used by non-Windows services. Instead, developers should implement their own service hosting programs.

and

A service runs as a background process that can affect system performance, responsiveness, energy efficiency, and security.

So a given service can run within a single process, or several services can run within a process. A service process can be multi-threaded, as per "Multithreaded Services" in Microsoft's documentation. A server for a network protocol running over a connection-oriented transport layer, for example, might have a thread for each connection (that might be done with separate processes per connection on a UN*X system).

Windows 7's Task Manager's "Processes" appear to be processes in the general computing lexicon, in that they are associated with a particular executable image. Windows 10's Task Manager's "Processes" appears to show groups of processes, with individual processes under it; perhaps that's what you're referring to as "super-processes". The "Details" view in the W10 Task Manager is similar to the "Processes" view in W7's Task Manager, showing processes in the general computing lexicon - and Windows API - sense. Guy Harris (talk) 19:11, 3 July 2019 (UTC)