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Launched in 2001, ionCube PHP Accelerator (PHPA) was the first freely available PHP accelerator to compete with the commercial Zend Cache product. Created before ionCube Ltd. was founded and at a time when the performance of PHP was regarded as lackluster when compared to other popular web programming languages, [citation needed] PHPA showed that PHP can compete with other languages ...
On Linux, the CPU affinity of a process can be altered with the taskset(1) program [3] and the sched_setaffinity(2) system call. The affinity of a thread can be altered with one of the library functions: pthread_setaffinity_np(3) or pthread_attr_setaffinity_np(3). On SGI systems, dplace binds a process to a set of CPUs. [4]
A hash-rehash cache and a column-associative cache are examples of a pseudo-associative cache. In the common case of finding a hit in the first way tested, a pseudo-associative cache is as fast as a direct-mapped cache, but it has a much lower conflict miss rate than a direct-mapped cache, closer to the miss rate of a fully associative cache.
In contrast, in most traditional hash tables, a change in the number of array slots causes nearly all keys to be remapped because the mapping between the keys and the slots is defined by a modular operation. Consistent hashing evenly distributes cache keys across shards, even if some of the shards crash or become unavailable. [3]
In systems that rely on a backoff mechanism (e.g. exponential backoff), the clients will retry failed calls by waiting a specific amount of time between consecutive retries. In order to avoid the thundering herd problem, jitter can be purposefully introduced in order to break the synchronization across the clients, thereby avoiding collisions.
A cache has two primary figures of merit: latency and hit ratio. A number of secondary factors also affect cache performance. [1] The hit ratio of a cache describes how often a searched-for item is found. More efficient replacement policies track more usage information to improve the hit rate for a given cache size.
Database caching is a process included in the design of computer applications which generate web pages on-demand (dynamically) by accessing backend databases.. When these applications are deployed on multi-tier environments that involve browser-based clients, web application servers and backend databases, [1] [2] middle-tier database caching is used to achieve high scalability and performance.
In software engineering, a spinlock is a lock that causes a thread trying to acquire it to simply wait in a loop ("spin") while repeatedly checking whether the lock is available. Since the thread remains active but is not performing a useful task, the use of such a lock is a kind of busy waiting .