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[1] [2] [3] The effect on application performance of opcode caching varies widely, depending on factors such as the inherent execution time of the PHP application and the percentage of source code actually executed on a given request, and whether additional optimization steps are performed.
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 ...
It also supports callbacks for many events such as library loads, system calls, signals/exceptions and thread creation events. In 2020, it received the Programming Languages Software Award from ACM SIGPLAN. [1] Pin performs instrumentation by taking control of the program just after it loads into the memory.
Thus, cache stampede reduces the cache hit rate to zero and keeps the system continuously in congestion collapse as it attempts to regenerate the resource for as long as the load remains very heavy. To give a concrete example, assume the page in consideration takes 3 seconds to render and we have a traffic of 10 requests per second.
It alerts the client to wait for a final response. The message consists only of the status line and optional header fields, and is terminated by an empty line. As the HTTP/1.0 standard did not define any 1xx status codes, servers must not [ note 1 ] send a 1xx response to an HTTP/1.0 compliant client except under experimental conditions.
– If there is a M copy in a cache, the transaction is stopped and wait until the M cache updates the MM, then the transaction can continue and the data is read from MM. Both caches are set S – else the data is read from MM. If the "shared line" is "on" the cache is set S else E 2 – MESI "Intervention" from M and E (e.g. Pentium (R) II [14])
The Linux kernel serializes responses for requests to a single file descriptor, so only one thread or process is woken up. [2] For epoll() in version 4.5 of the Linux kernel, the EPOLLEXCLUSIVE flag was added. Thus several epoll sets (different threads or different processes) may wait on the same resource and only one set will be woken up.
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]