lifelock guarantee

　　Tolerance). 　　Consistency refers to the ability to read the most recent written data or errors for each read operation. 　　Availability is the ability to get a timely, non-error response for each request, but does not guarantee that the result of the request is based on the latest written data. Partition fault tolerance, refers to the network problem between nodes, even if some messages to the packet or delay, the entire system can continue to provi

existence of the MESI protocol or multicore system does not weaken our existing memory model at all.Well, here we are (roughly) talking about the native Mesi protocol (and the CPU that uses it, such as arm). Other processors use the Mesi extended variant. Common extensions include the "O" (owned) state, which is similar to the e-state and a means to guarantee consistency between caches, but it directly shares the contents of the dirty segments withou

First, start with the atomic operationStart with a relatively simple atomic (Java.util.concurrent is a queue-based contract and the queue, in many cases, uses the atomic operation, so begin here first).In many cases we just need a simple, efficient, thread-safe increment-decrement scheme. Note that there are three conditions: Simple, means that the programmer as little as possible to operate the underlying or to achieve a relatively easy; High efficiency means less consumption of re

Switch 1100 offers 12 or 24 10M Ethernet switching ports + 2 10/100m Ethernet adaptive ports. The feature is that stackable--superstack II Switch 3300/1100 can mix 4 devices and provide 8Gbps of non-blocking exchange capacity; Extensible--superstack II Switch 3300/1100, each device has an extensible slot, can provide Gigabit Ethernet module (SX/LX/TX), 100base-fx fiber module, the third layer switching module and stacking module; Third-tier exchange is supported, which provides users with more

operations.That is, only a simple read, assignment (and must assign a number to a variable, the reciprocal assignment of a variable is not an atomic operation) is the atomic operation.But here's one thing to note: Under 32-bit platforms, the reading and assignment of 64-bit data is done by two operations and cannot be guaranteed to be atomic. But it seems that in the latest JDK, the JVM has guaranteed that reading and assigning 64 bits of data is also atomic.As can be seen from the above, the J

backup process, the data is read-only and all write requests are blocked. for MySQL database, the current mainstream backup software mainly has mysqldump and xtrabackup two kinds. mysqldumpThe mysqldump is a mysql-brought backup tool that exports data from a database to a . sql file by using SQL statements such as CREATE TABLE, drop table, and insert INTO. Because the file is readable, it is called a logical backup. To ensure the consistency of the backup data,mysqldump provides the foll

different points of view in detail. But we're not going to involve too many consistency theories and concurrency models, because this is beyond the scope of this article, and I'll just use a few simple features that make up a streamlined system. Read/write consistency. From a read-write standpoint, the basic goal of the database is to make the replica converge as short as possible (i.e., the time that the update is passed to all replicas) to ensure eventual consistency. In additi

[B] Three ways to ensure thread safety: [/b]Do not access shared variables across threadsTo make a shared variable the final typeTo synchronize the operation of a shared variableIt's easier to design a class as thread-safe from the start than to fix it later.Write multithreaded programs, first of all to ensure that it is correct, and then consider the performance.Stateless or read-only objects are always thread-safe.Do not expose a shared variable to a multithreaded environment (no synchronizati

segments have no space, we will skip this step. 5. Can we steal any expired extent from other online segments? 6. If there is any automatically extended datafile in the tablespace, we will expand the data file in the tablespace to allocate space. Skip this step if there is no automatically extended datafile in the tablespace 7. If retention is guaranteed, we cannot automatically tune undo, and an error will be thrown. 8. We try to use a low UNDO_RETENTION value to confirm: Can we release so

, we can assume that the entire step is atomic, but in a multithreaded environment, Java only guarantees that the basic data type of variables and assignment operations is atomic ( Note: In a 32-bit JDK environment, the reading of 64-bit data is not atomic operations *, such as Long, Double). To ensure atomicity in a multi-threaded environment, it can be ensured by locks and synchronized. Volatile is no guarantee of the atomicity of composite

, thus increasing the CPU's computational speed.Memory Order conflicts: Memory sequence conflicts are generally caused by false sharing, which means that multiple CPUs simultaneously modify different parts of the same cache line and cause one of the CPUs to be invalid, and the CPU must empty the pipeline when this memory sequence conflict occurs. How the processor implements atomic operationsThe 32-bit IA-32 processor uses atomic operations between multiple processors using a method based on cac

progress after a finite number of steps, and the completion O F The method is signalled via some additional mechanism (it might is a registered callback, a future, or a message).A synchronous API may use the blocking to implement Synchrony, but this is not a necessity. A very CPU intensive task might give a similar behavior as blocking. In general, it's preferred to use asynchronous APIs, as they guarantee, the system was able to progress. Actors is

, $callback); Using this code we can is sure that even if you kill a worker using CTRL + C while it is processing a message, nothing would Be lost. Soon after the worker dies all unacknowledged messages would be redelivered. With this code we can guarantee that God's horse will never be lost, even if you drop it with CTRL + C while the worker is handling the message. If the worker is killed, soon All unconfirmed messages will be re-dispatched. F

. You will be charged for the transfer of copies. You also have the right to choose to provide a guarantee in exchange for a certain fee. 2. You can modify one or several copies of a program or any part of the program to form a program-based work. As long as you meet all of the following conditions, you can copy and publish the modified program or work as required in the first section. A) You must include a clear description in the modified file: You

=" height= "class=" Amd-center "src=" http://img.orchome.com:8888/group1/M00/00/01 /kmcudlf7d-oaejy8aaboxglnmi4173.png "alt=" screenshot "/>2 Kafka cluster hosts 4 partitions (P0-P3), 2 consumer groups, consumer group A has 2 consumer instances, and consumer group B has 4.As with traditional messaging systems, Kafka guarantees that the order of messages is constant. Just a few more words. The traditional queue model keeps messages, and ensures that their sequencing remains the same. However, alt

retention is guaranteed, we cannot automatically tune undo, and an error will be thrown. 8. We try to use a low undo_retention value to confirm: Can we release some space through doing any hinted shrinking of segments without violating any retention guarantee? 9. If we still have no space and are guaranteeing retention (are guaranteeing retention), an error will be thrown. 10. We use auto tuned and cannot guar