- pthread_once_t in dynamically allocated (and freed) memory? - 3 Updates
- MIT AGI: Future of Intelligence (Ray Kurzweil) - 1 Update
- Theresa May Speaks Artificial Intelligence at World Economic Summit in Davos, Switzerland - 1 Update
- 2018 Isaac Asimov Memorial Debate: Artificial Intelligence - 1 Update
- AI Developers Are Getting Desks Next to Their Bosses - 1 Update
- Read again, i correct about my Threadpools - 1 Update
- Regression Testing Strategies: an Overview - 1 Update
| dave@boostpro.com: Feb 25 11:09AM -0800 Hi, I want to dynamically allocate memory, then once, on demand, thread-safely initialize part of that memory, and potentially free the memory. Then later I want to repeat the process with what is potentially the same memory block (and thus the same address of pthread_once_t) that has been returned from the allocator. Does this a. "just work" as long as it is set up with PTHREAD_ONCE_INIT, or b. do I need to do insert some kind of fence to ensure that all threads see the re-initialized memory, or c. never work; don't do that! d. something else I haven't thought of? I ask because all the examples I can find store the pthread_once_t in static storage and never re-initialize it. Thanks in advance, Dave |
| Kaz Kylheku <217-679-0842@kylheku.com>: Feb 26 02:29AM > b. do I need to do insert some kind of fence to ensure that all threads see the re-initialized memory, or > c. never work; don't do that! > d. something else I haven't thought of? It must work. Firstly, POSIX says that PTHREAD_ONCE_INIT is a constant. Thus it may be used in assignment. This is important because, by contrast, the PTHREAD_MUTEX_INITIALIZER is described as a macro that can be used for initialization, and not a constant. Secondly, there is a storage restriction on the phread_once_t control variable: namely, it may not be defined in automatic storage (i.e. non-static local variable). There is no restriction against pthread_once_t being in dynamic storage. > I ask because all the examples I can find store the pthread_once_t in > static storage and never re-initialize it. However, if that is in a shared library, it's dynamic anyway. The dynamic case is effectively exercised any time a shared library is dlopen'ed that has a file scope pthread_once_t. |
| dave@boostpro.com: Feb 25 10:10PM -0800 On Sunday, February 25, 2018 at 6:29:49 PM UTC-8, Kaz Kylheku wrote: > > c. never work; don't do that! > > d. something else I haven't thought of? > It must work. Well, I realize that's what the docs seem to imply, but… > Thus it may be used in assignment. This is important because, by > contrast, the PTHREAD_MUTEX_INITIALIZER is described as a macro > that can be used for initialization, and not a constant. Sure, but when I assign it, I am doing nothing to ensure that assignment is visible to all threads before they call pthread_once on it. Therefore it seemed plausible that another core's cache still contains some other value for that memory location, and a thread running on that core and calling pthread_once would see the uninitialized value instead of PTHREAD_ONCE_INIT, and skip calling the initialization function, which would be a problem… > However, if that is in a shared library, it's dynamic anyway. The > dynamic case is effectively exercised any time a shared library is > dlopen'ed that has a file scope pthread_once_t. Hm, you make a good point. But you know how tricky races are; I wouldn't count on all that exercise to have flushed out a bug if this issue wasn't totally considered. |
| computer45 <computer45@cyber.com>: Feb 25 06:36PM -0500 Hello.. Read this.. Here is a very interesting video: MIT AGI: Future of Intelligence (Ray Kurzweil) https://www.youtube.com/watch?v=9Z06rY3uvGY Thank you, Amine Moulay Ramdane. |
| computer45 <computer45@cyber.com>: Feb 25 04:42PM -0500 Hello.. Read this: UK Prime Minister is criticizing the far-right and the far-left for there incapacity to recognize the benefits of globalization of economy etc. please listen to UK Prime Minister in the following video (because she is really smart) to understand more: Theresa May Speaks Artificial Intelligence at World Economic Summit in Davos, Switzerland https://www.youtube.com/watch?v=tNhsm0oDkSw Thank you, Amine Moulay Ramdane. |
| computer45 <computer45@cyber.com>: Feb 25 03:56PM -0500 Hello... Read this: 2018 Isaac Asimov Memorial Debate: Artificial Intelligence Read more here: https://www.youtube.com/watch?v=gb4SshJ5WOY Thank you, Amine Moulay Ramdane. |
| computer45 <computer45@cyber.com>: Feb 25 03:20PM -0500 Hello.. Read this: AI Developers Are Getting Desks Next to Their Bosses Read more here: https://www.developer.com/daily_news/ai-developers-are-getting-desks-next-to-their-bosses.html Thank you, Amine Moulay Ramdane. |
| computer45 <computer45@cyber.com>: Feb 25 03:08PM -0500 Hello... Read this: More precision about my efficient Threadpools that scale very well, my Threadpools are much more scalable that the one of Microsoft, in the workers side i am using scalable counting networks to distribute on the many queues or stacks, so it is scalable on the workers side, on the consumers side i am also using lock striping to be able to scale very well, so it is scalable on those parts, on the other part that is work stealing, i am using scalable counting networks, so globally they scales very well, and since work stealing is "rare" so i think that my efficient Threadpools that scale very well are really powerful, and they are much more optimized and the scalable counting networks eliminate false sharing, and they work with Windows and Linux And i have updated the html tutorials inside the zip files, please read them. You can download them from: https://sites.google.com/site/aminer68/an-efficient-threadpool-engine-that-scales-very-well and from: https://sites.google.com/site/aminer68/an-efficient-threadpool-engine-with-priorities-that-scales-very-well Thank you, Amine Moulay Ramdane. |
| computer45 <computer45@cyber.com>: Feb 25 03:03PM -0500 Hello.... Regression Testing Strategies: an Overview Read more here: https://www.infoq.com/articles/regression-testing-strategies Thank you, Amine Moulay Ramdane. |
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