kiosk lock

MySQL Lab 1 .? MySQL concurrency and Isolation Control Mechanism Meta-data metadata lock: Implemented in the tablecache cache, provides isolation operations for DDL (DataDefinitionLanguage. A special meta-data metadata type called NameLock. (SQL layer) table-level data lock (SQL layer) storage engine-specific mechanism ro MySQL Lab 1 .? MySQL concurrency and Isolation Control Mechanism Meta-data metadata

Lock a table of a databaseSELECT * from table with (HOLDLOCK)Note: The difference between a table that locks a databaseSELECT * from table with (HOLDLOCK)Other transactions can read the table, but cannot update the deleteSELECT * from table with (TABLOCKX)Other transactions cannot read tables, updates, and deletesFeature description for "Lock options" in SELECT statementsSQL Server provides a powerful and c

Tags: style io ar os using SP for data onOracle Lock table row-level lock table-level lock ----row is locked exclusively ----Other users cannot modify this line until a row's lock is released----use the commit or the rollback command to release the lock ----Oracle by using I

Tags: operation unique index nod implementation action hit principle BSP MySQL Lock process detailed (1)-Basics MySQL plus lock process details (2)-about MySQL read comprehension MySQL plus lock process details (3)-about MySQL read comprehension MySQL Lock process detailed (4)-select for Update/

One: Java multi-threaded mutex, and Java multithreading introduce the reason for the bias lock and lightweight lock? --->synchronized of the weight of the lock, that is, when the thread runs to the code block, the program's running level from the user state to the kernel state, to suspend all the threads, so that the CPU through the operating system instructions,

The exclusive lock is also called the Write lock ((eXclusive lock, précis-writers is the x lock), if the transaction T to the data object a plus x lock, then only allow T to read and modify a, no other transaction can be a plus any type of

First, Introduction Before we explain these lock concepts, we need to be clear that these locks are not equivalent to Reentratlock locks in the Java API, which are conceptually, the locking mechanisms that are created in JDK1.6 to optimize the synchronized synchronization keyword. The startup and shutdown policies for these locks can be set by setting the JVM startup parameters, and of course, in general, using the JVM default policy. second, Mark Wo

pessimistic lock, optimistic lock, only applicable to update operation In the actual production environment, if the concurrency is not small, can use pessimistic locking method, this method is very convenient and simple to use.However, if the concurrency of the system is very large, pessimistic locking can lead to very large performance problems, so choose optimistic locking method. Pessimistic locking ass

Shared lock "s lock"Also called a read lock, if the transaction T with the data object a plus s lock, then the transaction T can read a but cannot modify a, the other transaction can only a plus s lock, and cannot add x lock, unti

shared lock (S lock) and exclusive lock (x Lock) Category: Database 2008-11-07 10:53 4409 people read reviews (2) favorite report Shared lock "s lock"Also called a read lock, if the t

Java synchronized keyword usage and level of Lock: Method Lock, Object lock, Class lock Reproduced from: http://blog.csdn.net/le_le_name/article/details/52348314 Java built-in locks: Each Java object can be used as a lock that implements synchronization, and these locks be

Shared lock "s lock"Also called a read lock, if the transaction T with the data object a plus s lock, then the transaction T can read a but cannot modify a, the other transaction can only a plus s lock, and cannot add x lock, unti

1. Features:The thread that has acquired the lock requests the lock again, which can be obtained directly.2. Realize:Custom internal class Sync, inheriting Abstarctqueuedsynchronizer:2.1. Get lock : Lock ()A, Fair lock:Acquire (1)B, non-fair lock:if (compareandsetstate (0, 1))CAS, the current state is 0, the current th

One: Java multi-threaded mutex, and Java multithreading introduce the reason for the bias lock and lightweight lock? --->synchronized of the weight of the lock, that is, when the thread runs to the code block, the program's running level from the user state to the kernel state, to suspend all the threads, so that the CPU through the operating system instructions

Reentrantlock is a reentrant lock that can support a thread to repeatedly lock resources, and he also supports fair locking and unequal locking. The Synchronized keyword also implicitly supports re-enter, such as a recursive method of synchronized modification, when the method executes, The execution thread can still obtain the lock multiple times after acquiring

Original link: http://www.jb51.net/article/50047.htmPage level: Engine BDB.Table level: Engine MyISAM, understood to lock the entire table, can read at the same time, write NoRow level: Engine INNODB, single row of records plus lockTable level, which locks the entire table directly, and other processes cannot write to the table during your lock. If you are writing a loc