Re:OS/2 2.0, Summer ’91 Edition
by JdeBP on Monday April 10, 2017 @01:24AM
(#14076265)
> OS/2 also had a single threaded event queue
This is another myth, long since debunked (I saw this one debunked in the early 1990s.) to resurface here all of these years later.
OS/2 had multithreaded input handling. Every application had its own event queue. Indeed, Presentation Manager allowed every thread in every application, that actually used Presentation Manager, to have its own event queue. A PM thread first created an "anchor block", then using (its handle to) that anchor block created a message queue.
What OS/2 had was synchronous input handling. Windows NT has desynchronized input handling.
The idea that "OS/2 had a single input queue" whereas "Windows NT has multiple input queues" is an erroneous one based upon an erroneous description of the twain. In fact, both Windows NT and OS/2 have a single system input queue. In Windows NT, this is called the raw input queue, and by the same erroneous logic that OS/2 "had a single input queue" so too does Windows NT, because the queue that people point to as the supposed reason that OS/2 had one queue is the OS/2 equivalent of that raw input queue.
It is not the number of queues, and never has been the number of queues. Presentation Manager had multiple event queues. It is the synchronous nature of processing input events versus the desynchronized way of processing them. This deals not in the number of queues at all, but in how the GUI model copes with things that need synchronization amongst multiple applications, such as (for example) all of the messages that fly about under the covers (amongst those multiple queues) as part of a keyboard focus change.
This is another myth, long since debunked (I saw this one debunked in the early 1990s.) to resurface here all of these years later.
OS/2 had multithreaded input handling. Every application had its own event queue. Indeed, Presentation Manager allowed every thread in every application, that actually used Presentation Manager, to have its own event queue. A PM thread first created an "anchor block", then using (its handle to) that anchor block created a message queue.
What OS/2 had was synchronous input handling. Windows NT has desynchronized input handling.
The idea that "OS/2 had a single input queue" whereas "Windows NT has multiple input queues" is an erroneous one based upon an erroneous description of the twain. In fact, both Windows NT and OS/2 have a single system input queue. In Windows NT, this is called the raw input queue, and by the same erroneous logic that OS/2 "had a single input queue" so too does Windows NT, because the queue that people point to as the supposed reason that OS/2 had one queue is the OS/2 equivalent of that raw input queue.
It is not the number of queues, and never has been the number of queues. Presentation Manager had multiple event queues. It is the synchronous nature of processing input events versus the desynchronized way of processing them. This deals not in the number of queues at all, but in how the GUI model copes with things that need synchronization amongst multiple applications, such as (for example) all of the messages that fly about under the covers (amongst those multiple queues) as part of a keyboard focus change.