| aminer68@gmail.com: Jul 09 05:59PM -0700 Hello, Lockfree bounded LIFO stack and FIFO queue version 1.01 Author: Amine Moulay Ramdane is the inventor of the Lockfree LIFO stack and he has corrected and enhanced the Lockfree FIFO queue Description: A fast Lockfree FIFO queue and a fast lockfree LIFO Stacks, they are bounded, the Lockfree FIFO queue was corrected and enhanced by Amine Moulay Ramdane and it doesn't have false sharing, also Amine Moulay Ramdane has invented a lockfree LIFO stack that doesn't need ABA prevention and it doesn't need Hazard pointers and it is not complicated and it doesn't have false sharing, please look at its source code inside LockfreeStackBounded.pas. Wait-free and lock-free algorithms enjoy more advantages derived from their definitions: Thread-killing Immunity: Any thread forcefully killed in the system won't delay other threads. Signal Immunity: The C and C++Standards prohibit signals or asynchronous interrupts from calling many system routines such as malloc. If the interrupt calls malloc at the same time with an interrupted thread, that could cause deadlock. With lock-free routines, there's no such problem anymore: Threads can freely interleave execution. Priority Inversion Immunity: Priority inversion occurs when a low-priority thread holds a lock to a mutex needed by a high-priority thread. Such tricky conflicts must be resolved by the OS kernel. Wait-free and lock-free algorithms are immune to such problems. An unbounded queue can hold infinite number of messages, while bounded - up to some predefined limit. If the limit is reached further enqueue operations fail. Note that array-based queue are always bounded. On first sight unbounded queues are more attractive (because they allow you to not care). But they are not. They are dangerous. What will happen if your queue will grow up to 10^6 messages? 10^7? 10^8? 10^9? What? It should not happen? So why you put an unbounded queue in the first place? In 95% of cases you need a bounded queue, because it will enforce what you think should happen, and will save you from bad things, it is the same for Stacks. Read the following paper: https://arxiv.org/pdf/1311.3200.pdf This paper suggests a simple solution to this problem. We show that, for a large class of lock- free algorithms, under scheduling conditions which approximate those found in commercial hardware architectures, lock-free algorithms behave as if they are wait-free. In other words, programmers can keep on designing simple lock-free algorithms instead of complex wait-free ones, and in practice, they will get wait-free progress. It says on the Analysis of the Class SCU(q, s): "Given an algorithm in SCU(q, s) on k correct processes under a uniform stochastic scheduler, the system latency is O(q + s*sqrt(k), and the individual latency is O(k(q + s*sqrt(k))." So i think lockfree algorithms are very interesting to work with, and the lockfree algorithms inside my zipfile are of the SCU(q, s) Class of Algorithms, so they are powerful. The size of the queue and the stack must be passed to the constructor and it must be the power of 2. You can download them from my website here: https://sites.google.com/site/scalable68/lockfree-bounded-lifo-stack-and-fifo-queue Language: FPC Pascal v2.2.0+ / Delphi 7+: http://www.freepascal.org/ Operating Systems: Windows, Mac OSX , Linux on (x86)... Required FPC switches: -O3 -Sd -Sd for delphi mode.... Required Delphi switches: -$H+ {$DEFINE CPU32} and {$DEFINE Windows32} for 32 bit systems {$DEFINE CPU64} and {$DEFINE Windows64} for 64 bit systems Thank you, Amine Moulay Ramdane. |
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