When can 64-bit writes be guaranteed to be atomic, when programming in C on an Intel x86-based platform (in particular, an Intel-based Mac running MacOSX 10.4 using the Intel compiler)? For example: unsigned long long int y; y = 0xfedcba87654321ULL; /* ... a bunch of other time-consuming stuff happens... */ y = 0x12345678abcdefULL; I...
In my multithreaded application and I see heavy lock contention in it, preventing good scalability across multiple cores. I have decided to use lock free programming to solve this. How can I write a lock free structure? ...
I am new to .net and would like to know whether .net has the java equivalent of AtomicInteger, ConcurrentLinkedQueue, etc? I did a bit of search and couldnt come up with anything. The lock free algorithms need some sort of a CAS instruction, which is provided through the undocumented Unsafe class in Java, does .net have anything equiva...
Hi im trying to write a lockless list i got the adding part working it think but the code that extracts objects from the list does not work to good :( Well the list is not a normal list.. i have the Interface IWorkItem interface IWorkItem { DateTime ExecuteTime { get; } bool Cancelled { get; } void Execute(DateTime now); } ...
Does anyone know if there are any lock-free container libraries available for .NET ? Preferably something that is proven to work and faster than the Synchronized wrappers we have in .NET. I have found some articles on the .NET, but none of them specify any speed benchmarking, nor do they inspire much confidence in their reliability. T...
If I have a deeply immutable type (all members are readonly and if they are reference type members, then they also refer to objects that are deeply immutable). I would like to implement a lazy initialized property on the type, like this: private ReadOnlyCollection<SomeImmutableType> m_PropName = null; public ReadOnlyCollection<SomeImmu...
I'm running into a situation where I need the atomic sum of two values in memory. The code I inherited goes like this: int a = *MemoryLocationOne; memory_fence(); int b = *MemoryLocationTwo; return (a + b) == 0; The individual reads of a and b are atomic, and all writes elsewhere in the code to these two memory locations are also loc...
The standard union/find or Disjoint-set data structure has very good running times (effectively O(1)) for single threaded cases. However what is it's validity/performance under multi-threaded cases? I think that it is totally valid even without locking or any atomic operations aside from atomic pointer sized writes. Does anyone see any ...
Windows provides a lockless singly linked list, as documented at this page: Win32 SList I'm wondering if there's an existing good C++ wrapper around this functionality. When I say good, I mean it exports the usual STL interface as much as possible, supports iterators, etc. I'd much rather use someone else's implementation than sit down ...
I'm in the process of designing a system which connects to one or more stream of data feeds and do some analysis on the data than trigger events based on the result. In a typical multi-threaded producer/consumer setup, i will have multiple producer threads putting data into a queue, and multiple consumer threads reading the data, and the...
I have got an in memory data structure that is read by multiple threads and written by only one thread. Currently I am using a critical section to make this access threadsafe. Unfortunately this has the effect of blocking readers even though only another reader is accessing it. There are two options to remedy this: use TMultiReadExclu...
I'm attempting to write a lock-free version of a call queue I use for message passing. This is not for anything serious, just to learn about threading. I'm relatively sure my code is correct, except if the instructions are re-ordered or done in registers. I know I can use memory barriers to stop re-ordering, but how can I ensure values ...
I'm implementing a lock-free mechanism using atomic (double) compare and swap instructions e.g. cmpxchg16b I'm currently writing this in assembly and then linking it in. However, I wondered if there was a way of getting the compiler to do this for me automatically? e.g. surround code block with 'atomically' and have it go figure it out...
I'm writing a program with a consumer thread and a producer thread, now it seems queue synchronization is a big overhead in the program, and I looked for some lock free queue implementations, but only found Lamport's version and an improved version on PPoPP '08: enqueue_nonblock(data) { if (NULL != buffer[head]) { return EWO...
Herlihy and Shavit's book (The Art of Multiprocessor Programming) solution to memory reclamation uses Java's AtomicStampedReference<T>;. To write one in C++ for the x86_64 I imagine requires at least a 12 byte swap operation - 8 for a 64bit pointer and 4 for the int. Is there x86 hardware support for this and if not, any pointers on ho...
I've found several implementations for single producer-single consumer, but none for multiple producer-single consumer. Does a lock-free queue for "multiple producers-single consumer" exist for Delphi? ...
I just found this: http://www.emadar.com/fpc/lockfree.htm at first glance it looks fine. Is anybody using it? Or maybe somebody already looked at it and found it unusable? ...
I've found following article: Use GCC-provided atomic lock operations to replace pthread_mutex_lock functions It refers to GCC Atomic Builtins. What the article suggest, is to use GCC atomic builtins instead of pthread synchronization tools. Is this a good idea? PS. The mysql post is obviously misleading. Atomic Builtins can't replac...
Is there any small library, that wrapps various processors' CAS-like operations into macros or functions, that are portable across multiple compilers? PS. The atomic.hpp library is inside boost::interprocess::detail namespace. The author refuses to make it a public, well maintained library. Lets reopen the question, and see if there ar...
I ve been googling quite a bit for a lock-free queue in C++. I found some code and some trials - but nothing that i was able to compile. A lock-free hash would also be welcome. SUMMARY: So far i have no positive answer. There is no "production ready" library, and amazingly none of the existent libraries complies to the API of STL contai...