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
, you don't know what to do with the taskbar, the taskbar becomes wider, and sometimes it just disappears. So Win7 's taskbar suddenly widened. How do I narrow the taskbar? The following small series for everyone to introduce the details, will not friends can come to refer to, to see
Whether intentionally or unintenti
Solution One1, right click on the taskbar selection properties, remove the "lock taskbar" before the check, according to the application (if you have removed the lock this option is not set up).2, with the mouse along the top of the wide edge, when the mouse to form a double arrow, with the left press and hold on, the
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
As Windows 7 uses more time, it is becoming increasingly difficult to find a very awkward problem, with the taskbar space getting smaller. Because accustomed to the Windows 7 taskbar lock icon function, inadvertently put a variety of program icons into the taskbar up. Although we can use the
As Windows 7 uses more time, it is becoming increasingly difficult to find a very awkward problem, with the taskbar space getting smaller. Because accustomed to the Windows 7 taskbar lock icon function, inadvertently put a variety of program icons into the taskbar up. Although we can use the
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
How to restore the taskbar to a major problem, can be a difficult problem of cattle anti-virus toolbox easy to solve.
Believe in Daily computer operation, you will also encounter this situation: Windows taskbar widening, or dislocation. In fact, these situations generally exist in the use of most users. Recently a large number of netizens have proposed how to restore the
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
The function and use of the Windows operating system taskbar is convenient for us to operate, and the computer in use will inevitably encounter some difficult problems, recently, a user in the Win7 64-bit flagship system found that the taskbar display abnormal, white or other colors, taskbar program icon also shows the exception, it is very affecting the system b
Windows 7 During the first use, many friends felt that the taskbar had changed. " No. " , Not suitable. They often ask in groups or in soft media forums: Windows 7 Quick Start of the taskbar below (Quick Launch) Where did the region go? Those Quick Start IE Browser Why are there no small icons?After all, the operating system and common software have a habit. Microsoft has always been Windows Does t
Win7 's Super taskbar brings a lot of convenience to the user, allowing the computer to operate more quickly, but to give full play to the role of the Super taskbar, but also to speak a little skill.
Steps/Methods
1, the common software locked in the taskbar. To run the software you want to lock down, click the "Righ
icon in the taskbar, the icon displays a preview thumbnail of the open file, and when you move the mouse over any of the thumbnails, the window is displayed on the desktop, the mouse is removed, the window disappears, and the desktop is restored.
If the user clicks a program icon in the taskbar with the mouse, the program icon displays a thumbnail that can be paused, moves the mouse over any of the thumbn
, so we should delete all the eye-catching icons first; 4. Right-click the taskbar, remove the check mark before "Lock the taskbar", and then right-click the created Quick lauch, remove the check boxes before "Show title" and "Show text. Right-click the location of Quick lauch and select "View" to set the Icon size. 5. OK, now you can drag and drop the remaining
1. As shown in the following illustration, our computer taskbar runs to the right, and I now right click on the taskbar on the right side of the screen as shown in the picture:2. Then in the pop-up menu we hand-held to the "lock the taskbar" to click on it to cancel the "lock
The Win7 system canceled the Quick start, but the fast start function is still available, you can put the commonly used programs in the taskbar, when it is convenient to open
① Add the program you want to the taskbar: (Right-click the program or shortcut, and choose to lock into the taskbar.) You can also drag the pro
When we drag the Windows 7 taskbar to the vertical display of the window edge, we will find that the height of the Windows taskbar is too wide, occupying a lot of screen area. However, no matter how we drag the taskbar, it cannot be further reduced. Even if we can hide it, it cannot change the situation where the height of the
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