atomic

问题 Is a single row INSERT atomic (for an external reader)? Imagine it happens on a table with 1M columns. While executing a single INSERT statement (namely, the "single row" kind), is it possible for a read operation (maybe using the 'Read uncommitted' isolation level) occurring at the same time to only read some of the values (columns) ? I'm particularly interested in MS SQL Server's behaviour, although I assume this is similar for all major vendors. Bonus cred points for a link to official

问题 I have a piece of serial code which does something like this if( ! variable ) { do some initialization here variable = true; } I understand that this works perfectly fine in serial and will only be executed once. What atomics operation would be the correct one here in CUDA? 回答1: It looks to me like what you want is a "critical section" in your code. A critical section allows one thread to execute a sequence of instructions while preventing any other thread or threadblock from executing those

问题 I have a piece of serial code which does something like this if( ! variable ) { do some initialization here variable = true; } I understand that this works perfectly fine in serial and will only be executed once. What atomics operation would be the correct one here in CUDA? 回答1: It looks to me like what you want is a "critical section" in your code. A critical section allows one thread to execute a sequence of instructions while preventing any other thread or threadblock from executing those

问题 I have a piece of serial code which does something like this if( ! variable ) { do some initialization here variable = true; } I understand that this works perfectly fine in serial and will only be executed once. What atomics operation would be the correct one here in CUDA? 回答1: It looks to me like what you want is a "critical section" in your code. A critical section allows one thread to execute a sequence of instructions while preventing any other thread or threadblock from executing those

问题 The "Treiber Stack" is generally one of the simplest lock-free data structures, and so it is often used when teaching introductions to lock-free algorithms. I've seen many implementations of Treiber Stacks using C++ atomics. The algorithm itself is trivial, so the real challenge is handling all the other incidental details of lock-free data-structures, such as providing some way of performing safe memory reclamation, avoiding the ABA problem, and allocating nodes in a lock-free manner. This

问题 Does OpenMP support an atomic minimum for C++11? If OpenMP has no portable method: Is there some way of doing it using a x86 or amd64 feature? In the OpenMP specifications I found nothing for C++ but the Fortran version seems to support it. See 2.8.5 of the v3.1 for the details. For C++ it states binop is one of +, *, -, /, &, ^, |, <<, or >>. but for Fortran it states intrinsic_procedure_name is one of MAX, MIN, IAND, IOR, or IEOR. In case you are interested in more context: I am looking for

问题 Does OpenMP support an atomic minimum for C++11? If OpenMP has no portable method: Is there some way of doing it using a x86 or amd64 feature? In the OpenMP specifications I found nothing for C++ but the Fortran version seems to support it. See 2.8.5 of the v3.1 for the details. For C++ it states binop is one of +, *, -, /, &, ^, |, <<, or >>. but for Fortran it states intrinsic_procedure_name is one of MAX, MIN, IAND, IOR, or IEOR. In case you are interested in more context: I am looking for

问题 Does OpenMP support an atomic minimum for C++11? If OpenMP has no portable method: Is there some way of doing it using a x86 or amd64 feature? In the OpenMP specifications I found nothing for C++ but the Fortran version seems to support it. See 2.8.5 of the v3.1 for the details. For C++ it states binop is one of +, *, -, /, &, ^, |, <<, or >>. but for Fortran it states intrinsic_procedure_name is one of MAX, MIN, IAND, IOR, or IEOR. In case you are interested in more context: I am looking for

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . I'm looking for some nice real-world examples of the ABA-problem causing trouble in multithreaded code. The ABA-problem occurs in

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . I'm looking for some nice real-world examples of the ABA-problem causing trouble in multithreaded code. The ABA-problem occurs in