automic

();//The system will ensure that a thread is always doing the task for you, and if that thread dies, the system creates another thread instead. Create a thread pool for timed processing: Executors.newscheduledthreadpool (3). Schedule () Method Note: For threads that have completed all tasks, the wait state is required, so the last The shutdown method of the executors class destroys the thread that finishes the task. * */Executorservice Pool=executors.newfixedthreadpool

, which leads us to be unable to guarantee that their invocation is carried out in the correct order, possibly in the Newcharacter () Paintcomponent () method has been redrawn canvas before the method was invoked. Competition, in addition to the two methods to access the same data, and they are not automic related. When we were in junior high, we learned that atoms were once considered to be the smallest unit, not to be divided, even if it has now pr

once. Do () Implementation of the idea, ONCE.M is a mutex, in the Do () operation, the mutual exclusion operation; Once.done is a flag variable that indicates whether do () is performed. The specific implementation of Do () is as follows: Func (o *once) do (f func ()) { If atomic. LoadUint32 (o.done) = = 1 { Return } O.m.lock () Defer O.m.unlock () If O.done = = 0 { Defer automic. StoreUint32 (o.done, 1) F () } } The implementation idea is basical

////Dog.h//oc2_ Reference Count////Created by zhangxueming on 15/6/18.//Copyright (c) 2015 zhangxueming. All rights reserved.//#import@interfacedog:nsobject{NSString*_name; Nsinteger _age;} @property (copy, nonatomic) NSString*Name: @property (nonatomic) Nsinteger age;@end////DOG.M//oc2_ Reference Count////Created by zhangxueming on 15/6/18.//Copyright (c) 2015 zhangxueming. All rights reserved.//#import "Dog.h"@implementationDog@end////main.m//oc2_ Reference Count////Created by zhangxueming on

Synchronization: Shared resources are called by multiple threads and are synchronized in several ways: (Scenario: Selling train tickets)1 syncnizerd Keywords2 Reentrantlock Row It lock3 volatile keyword modifier variable;Async: Changing the state of the thread itself, there are several async methods: (Scenario: Producer consumer mode)1 wait notify, the wake mechanism of Object;2 await asign; Two methods of Condition objects;3 Block Queue Bolckqueue, its bottom is still condition;After JDK 5, for

Chinese Wyl 20021015 Xmloutputter outputter = new Xmloutputter ("", True, "GB2312"); out = new Bufferedoutputstream (new FileOutputStream (tempfile)); Increase this row so that the XML file has no blank lines. Wyl 20021030 Outputter.settextnormalize (TRUE); Outputter.output (Doc, out); } catch (Exception e) { E.printstacktrace (); There were errors so abort replacing the old property file. Error = TRUE; } finally { try {out.close (); } catch (Exception e) { E.printstacktrace (); Error = TRUE; }

() method. This competition requires synchronous locks to be implemented. We must obtain the lock to make sure that the condition is checked and set to Automic, that is, the inspection and setting must be in the lock range. As we mentioned above, the Wait () method releases the lock and then retrieves the lock, so is there any competition happening during this period? Theoretically there will be, but the system will prevent this. The wait () method

the same situation in the future, I have recorded the solution in the manual! (Warning: Due to raid settings on the server, please use it with caution. Restoring the default settings by mistake is very likely to cause data loss !) This is because we have a new machine and no data! Haha 1. Press F2 at startup to enter BIOS settings 2. Light up the three lights on the keyboard by capsulelock, num lock, and scrol lock respectively. 3. press Alt + e to clear NVRAM and press Alt + F. Then, the syste

Upgrade the current replication to GTIDs and replicationgtids.Upgrade current replication to GTIDsPut all the master and slave1. Put all the master and slaveSet @ global. read_only = on; or set global read_only = on;2. Put all the master and slaveService mysql stop3. Enable GTIDs for all master and slaveTo enable GTIDs, you must configure gtid-mode, log-bin, and log-slave-updates on all machines,Enforce-gtid-consistency (before 5.6.9 is -- disable-gtid-unsafe-statement ),In addition, slave needs

1. @ property int age; In the case of a compiler, it will automatically compile and expand: Point syntax is P. Age > -(Void) setage :( INT) age; -(INT) age; 2. Likewise: @ property int _ age; In the case of a compiler, it will automatically compile and expand: -(Void) set_age :( INT) age; -(INT) _ age; Generally, use 1 instead of 2. @ Synthesize age = _ age; Access the member variable "_ age". If the member variable "_ age" does not exist, the system will automatically generate the member

of context switching 1) Use the profiling tool LMBENCH3 to measure the duration of the context switch 2) Use Vmstat to measure the number of context switches 3) Use the Jstack command to view the dump information for the thread(3) How to reduce context switching 1) No lock concurrent programming: Multi-threaded competition lock causes context switching, using lock-free programming to reduce context switching by avoiding the use of locks 2) CAS algorithm: CAS operation using

description of the class, the system defaults to the setter method of the variable to take a assign approach. In the header file. h typically has a defined instance variable in {}Example:. h @property (automic,retain) nsstring * ABC;. m @sythesize ABC; In the case of @sythesize ABC, the system will not automatically generate the instance variable "_ABC", directly through the variable name ABC, that is, directly using the variable name in the assignm

let the communicator back with the letter, the content is (Accepted);14) Staff Officer 1 received at least 2 generals (accepted) content, confirming that the attack time has been accepted by the majority.Four. Zookeeper Zab protocol Zookeeper automic Broadcast (ZAB), or Zookeeper atomic broadcast, is the Paxos Classic Implementation Terms: Quorum: A collection of more than half the cluster1. Nodes in ZAB (zookeeper) are divided into four states looki

Database Transactions (Database Transaction) refers to a series of operations performed as a single logical unit of work, either completely or completely out of execution.Open transaction: Start transaction;ROLLBACK TRANSACTION (if the transaction cannot be rolled back after commit): rollback;Commit TRANSACTION: Commit;4 major features of the transaction:1. atomicity (automic): Multiple sets of operations in the same transaction cannot be split, must

,},'Defaultopexception' =>{'Exitfunction' => "seh ",'Initialautorunscript' => 'migrate-F ',},'Platform' => 'win ','Targets' =>[['Automic ', {}],['Ie 6 on Windows XP SP3 ', {'max' => '0x40000', 'offset '=> '0x500'}],['Ie 7 on Windows XP SP3 ', {'max' => '0x40000', 'offset '=> '0x500'}]],'Privileged' => false,'Disclosuredate' => "Feb 17 2012 ",'Defaulttarget' => 0 ))Register_options ([OptBool. new ('obfuscate', [false, 'Enable JavaScript obfuscation'])]

/copy. Otherwise, you will receive a warning. Atomicity and non-atomicity can be specified. If it is retain/copy, an internal lock is automatically used to implement atomicity when automic is not specified. If you use the garbage collection mechanism, you can specify whether the reference is a strong reference or a weak reference, but this is informal. @ Synthesize firstname, lastname, age = yearsold; Attribute declaration with instance vari

Roots directory.• Auto Reload (automic reload): The resources in context are monitored by tomcat, and when the resource changes, Tomcat automatically reloads the resource file. While this feature is useful in the development process, it is very expensive to operate in a production environment and often requires a restart of the product application.Context ConfigurationThe context is unique, primarily because its configuration contains multiple option

assigned a pointer to the new memory area! Assign: It means that only the pointer to the target memory area is assigned to the variable, and the reference counter of that memory area does not change! 1, 22 points do not explain, 3 of retain, copy, assign all refers to, in the automatic generation of setter function, the compiler needs to identify a description of the word to generate corresponding setter function! It is important to note that if you do not add the class descriptor, the system

is assigned a pointer to the new memory area! Assign: It means that only the pointer to the target memory area is assigned to the variable, and the reference counter of that memory area does not change! 1, 22 points do not explain, 3 of retain, copy, assign all refers to, in the automatic generation of setter function, the compiler needs to identify a description of the word to generate corresponding setter function! It is important to note that if you do not add the class descriptor, the syste

prepare for the same situation in the future, I will be the description of the solution to record down!(Warning: Because there are RAID settings on the server, please use it carefully, and the default settings can cause data loss!) Because we are new machines, no data, so ignore! Oh1. Press F2 to enter BIOS setting when booting2. Press Capsulelock, Num Lock, Scrol lock to light the three lights on the keyboard respectively.3, first press alt+e combination, clear the NVRAM, and then press ALT+F