Re: ThreadSafe Note Scheduling Code (Was Re: Threading)
Re: ThreadSafe Note Scheduling Code (Was Re: Threading)
- Subject: Re: ThreadSafe Note Scheduling Code (Was Re: Threading)
- From: Bill Stewart <email@hidden>
- Date: Fri, 8 Aug 2003 15:36:04 -0700
On Friday, August 8, 2003, at 01:46 AM, Urs Heckmann wrote:
Am Freitag, 08.08.03, um 03:41 Uhr (Europe/Berlin) schrieb Bill
Stewart:
In your Render call, you get the thread ID (pthread_self), of the
thread that you are being asked to render on.
In your API calls for starting and stopping notes you compare that
thread ID with the thread ID you are being called on to start/stop a
note, If it is the render thread, then you go through and do the work
immediately, if not, you queue a start/stop note
Thanks, this is fairly simple 8-)
But now I have another one:
- Imagine an intelligent host on a multiprocessor machine.
- It sees a bunch of Notes comming. Hence it takes its measures.
- It transfers the rendering from cpu A to cpu B, probably changing
thread ID of rendering, right?
No - each time you render you get the ID of the render thread.
Bill
- The Queue is called, still on cpu A, finds the right thread ID and
assumes safe immediate processing
- Some cycles thereafter rendering starts on cpu B, it alters the
thread ID, but too late...
- process interrupts queue, both work on same data -> leak, crash,
hanging note, whatever
Couldn't that happen?
Hence, shouldn't one always use the thread safe queue and never assume
safe to process immediately?
Cheers,
;) Urs
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