lifelock guarantee

is MySQL purge log simple?simple: The Purge log function is simple, purge master logs to specify a binlog, then delete the Binlog file on the previous file system and update the Binlog.index file.Complex: need to guarantee purge atomic operation, how to guarantee that there is a crash recovery?I didn't read the code before and thought about the problem with the code implementation:1: If you delete more file

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 addition to this weaker

;} public synchronized int Getsomewithsync () {return some;} public void Setsome (int v) {some = V;} Public synchronized void Setsomewithsync (int v) {some = V;}}Let's analyze one thread to write and another to read in four scenarios. The initial situation is a = new A (), and no other threads are considered.Scenario One: Read and write are not synchronized. Thread1 Thread2 (1) a.setsome (13) (2) A.getsome () In this case

processor, but it is not flushed to main memory, or there is an old (or invalid) value in the cache of the read processor. The memory model determines when a thread can reliably "see" the Write to a variable by another thread . In particular, the memory model defines the semantics of volatile , synchronized , and final that guarantee the visibility of memory operations across threads. (in particular, the memory model defines semantics for volat

method will not be executed again, so the second code's self-help operation failed. In particular, the above description of the Finalize () method of the object's death may have tragic artistic overtones, and I do not encourage you to use this method to save the object. Instead, I recommend that you try to avoid using it, because it is not a destructor in C + +, but a compromise that is made easier for C + + programmers to accept when Java is first born. It is expensive, uncertain, and does not

total memory.This partitioning of memory space is based on the existence of only a small number of objects if, for each garbage collection, most objects are garbage. If an exception is encountered, the object that survived in a garbage collection exceeds the total size of the reserved survior space, which relies on other memory allocations (for the collection, which is also described in the previous narrative as a new generation method).Tag GroomingNormal tag cleanup leaves memory fragmentation

written from memory at any time, it will greatly reduce the running speed of the program, so there is a cache:While the program is running, the data required for the operation is copied from memory to the CPU's cache, and when the CPU is calculated, it can read and write data directly from its cache. After the operation is finished, the data in the cache is then written to memory.Let's go back and look at the four lines of code just now:int x=1;//给x赋值为1，这个操作会直接将10写入内存中int y=x;//这其实是两个操作,先读取x的值,

This article records the policy of ensuring concurrency security--invariance.(Note: It is immutable, not invariant!)Organizing a sequence of behaviors into an atomic operation to guarantee invariance conditions, or using a synchronization mechanism to guarantee visibility, to prevent reading of invalid data or objects from becoming inconsistent, is due to the sharing of mutable data.If we can

. Ensure the accuracy of data reading. But the reason for the lock is the least efficient. Not really applied. 9. Volatile does not guarantee the atomicity of the operation but ensures the visibility of the memory. That is, the data that is accessed between different threads is up-to-date. To ensure atomicity, you must use the Atomic class. This ensures that the read-write is atomic at the hardware level, unlike the normal int type, which is executed

guarantee that the Boolean expression evaluates to true; if the value is False, the program is already in an incorrect state. The system will give a warning or exit. Generally speaking, assertion is used to guarantee the most basic and critical correctness of a program. Assertion checks are typically opened during development and testing. To improve performance, the assertion check is usually turned off af

replace (String key,object value, Date expiry); /*** The data is stored asynchronously, now returned immediately, and later stored in the data* @param key* @param value*/public void Asynput (String key,object value);/*** Asynchronous decrement counter, does not guarantee the exhaustion success* @param key* @param DECR*/public void Asynaddordecr (String key,long decr);/*** Asynchronous cumulative counter, does not

of the next class. Now cows want to know which courses you can apply to minimize the amount of physical energy you spend moving between classrooms, and ask you to help him find the minimum. Input Format The first line is a four integer n,m,v,e. n indicates the number of time periods in the semester; M indicates the maximum number of classes the cow can apply for changing classrooms; v indicates the amount of classrooms in the cattle and cattle schools; e indicates the number of roads in the sch

into Cenozoic and old age, according to the age of the most appropriate algorithm; In the new generation, a large number of objects are found dead in every garbage collection, with little survival, with a replication algorithm (copying those that are alive, populating them into the memory space of the objects to be reclaimed, To set aside more contiguous memory areas); In the old age, because of the high survival rate of the object, there is no extra space to allocate it to

or a multiple-CPU system. Multitasking and multithreading are a good way to make the most of a multiprocessor system. Multithreading allows you to design more loosely coupled (more loosely-coupled) applications. Basic Threads The easiest way to create a thread is to inherit java.lang.Thread. This class has made the necessary configuration for the creation and operation of threads. Run () is the most important method of thread, and if you want the thread to do it for you, you must override th

protocol appears) The lower level provides services for the upper floors, each layer of their respective responsibilities, what they have done each layer, we are here only to say the network layer and above. The network layer is responsible for addressing, ensuring that data is delivered to the destination. When the data arrives, how the data is transmitted, how it interacts, whether the data is incorrect, and whether it is reliable, is guaranteed by the transport layer. Transport layer is divi

to be completed before the write operation succeeds. Visible O_sync do more than O_dsync. The Open () Referense also has a o_async, which is used primarily for terminals, pseudoterminals, sockets, and Pipes/fifos, which are signal-driven IO and send a signal when the device is read/write (SIGIO) , the application process captures the signal for IO operations. Both O_sync and o_direct are synchronous, meaning that only a successful write will return. Looking back, let's look at Inn

scenarios.However, we recommend that operations in a DB instance use local transactions to ensure consistency whenever possible, and a series of update operations across DB instances need to be done in different data sources based on transactional routing, and update operations between data sources need to be handled through distributed transactions .There are three main types of distributed transaction solutions: Two-phase commit protocol, maximum effort g