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cheap ;line .xml file configuration , If = = null ) {CharSequence pname ;if owner.pleased.InterlockedExchange ( &amp ;use synthetic ;} While wheel stop execution the use 值 ;set to true and retard if the original 值 ;true If the original 值 ;false the resources that have never additionally been acclimate Then set it as the use of If the aboriginal 值 ;true indicates that other threads are using this resource call the sleep to give up the phase slice scheduling Here assume that always use a rotating lock thread is running with the same priority But as a solo CPU system using a rotating bolt is of not significance The detection to the resource occupied the siesta to use can sleep a random time this alleviated on certain level the situation Spin lock namely assumed to be protected resources will only be occupied for a duration of period and a alternate to nucleus mode and wait this situation within a circulation access for efficiency will be higher Many developers will clarify the digit of cycles if it namely still incapable to course the resource afterwards the thread will switch to nucleus mode and has been waiting for to the resources easily This is the key duration of use In a multiple processor using spin bolt namely quite useful this namely because when a thread in a CPU running aboard repeatedly thread afresh CPU circular wait Again among a alone CPU system wheel bolt meaningless When CPU is read from the memory a byte it namely peruse from the memory a byte merely take a arsenal line Cache lines may be 32 bytes alternatively 64 bytes Depending aboard the cpu The warehouse line among order to amend the performance of This is forward to the procedures of the principle of locality If always the bytes among the storage line in the CPU does never absence path to the memory bus For multiprocessor environment the storeroom memory namely updated to acquaint more difficult :1: CPU1 reads one byte which makes the byte and its contiguous bytes to be read into the CPU1 storage 2: CPU2 reading to the same byte which makes the byte peruse CPU2 3: CPU1 aboard memory amid this byte is modified which makes the bytes to be written to the CPU1 told the storage and not written backward to memory 4: CPU2 read again to the same byte The byte namely among the CPU2 arsenal so CPU2 does not need to direction the memory But CPU2 can discern the bytes among memory surrounded the new 值 ;The situation namely quite wrong But CPU chip designers have considered this situation When a CPU modified arsenal line to a byte the vacation of the machine CPU ambition be notified and the warehouse line Therefore amid the earlier case CPU2 arsenal is invalid Cpu1 must be its cache namely written behind to the memory CPU2 must way the memory to fill its storage line We can perceive that although the arsenal can edit performance only aboard a multiprocessor machine it can likewise damage performance In order to edit the performance we ought according to the size of the arsenal to the application organization attach the data with a arsenal line siteline alignment And the data reading and writing data respectively Use the GetLogicalProcessorInformaiton function to get CPU cache line size We can use _declspec align ( # ) ) indicator to field alignment control Say so much measures only the best access namely to entire tell a CPU path data alternatively only allow a thread to access the data can entirely avert the storage line problem If we only absence to adjust a 值 atom ;so Interlock order function very well But surrounded maximum cases we need to process the data structure constantly than a easy 32 值 ;or 64 bit 值 ;more perplexing In order to enable atomic access to course complex data architecture using windows we can use other characteristics Using a rotating lock stop direction is quite wrong in some ways the best case namely while the thread to path the shared resource the thread have to call an operating system function differentiate the operating system itself for what resources If the resource is not easily the thread ambition enter the await state can not be scheduling If the operating system detects a resource namely accessible the system will this thread as scheduling status and way to this resource The volatile keyword tells the compiler that this variable may be applications outside of other things adaptation never aboard the variables to tell any form of optimization barely all read from memory within the 值 ;If it is not a variable with the volatile qualifier the compiler may have C+ ;+ ;code optimization as it aspiration be variable 值 ;is fraught into the enrol subsequent operations are aboard the register within the 值 ;operation and not repeated access memory For a architecture with volatile qualifier namely equivalent to the structure of forever of its members joined the volatile qualifier Critical section ( CriticalSection ) fussy section is a short code it forward execution requires preferential access to some shared resource In this way allows multiple lines of code with atomic access surrounded the fashionable thread to depart the fussy section onward any other thread scheduling system does not direction the opener partition For example surrounded a account management instance whether the account way namely never synchronized so a thread may be surrounded repeatedly thread surrounded the list of query to account join elements If two threads at the same time to account elements annexed among the situation want be even worse Use fussy section can mainly prevent the aboard circumstances To use fussy section 1st absence to define CRITICAL_SECTION structures Then any need to share the code aboard EnterCriticalSection and LeaveCriticalSection As Int g_a=0 ;CRITICAL_SECTION CS ;DWORD WINAPI ThreadProc1 ( PVOID ) {EnterCriticalSection ( &amp ,true religion 販売店;g_a ) as ( int ;i=0 ;i&lt ;g_a++ 100 ;i++ ) ;LeaveCriticalSection ( &amp ,moncler 新作;CS ) ;return 0 ;}DWORD WINAPI ThreadProc2 ( PVOID ) EnterCriticalSection ( &amp ;g_a ) ;for ( int i=0 ;i&lt ;100 ) ;i++ g_a++ ;LeaveCriticalSection ( &amp ;CS ) ;return 0 ; the authors accustom a quite vivid metaphor CRITICAL_SECTION building prefer a bathroom bathroom zone is to defend the resources At the same period only allows a person to enter the bathroom If there are multiple local needs protection can define multiple CRITICAL_SECTION architecture Incoming call EnterCriticalSection address of the CRITICAL_SECTION architecture this architecture identifier to access protected resources it namely equivalent to the bathroom When a man wants to go to the bathroom have to first retard the bathroom door on the occupation identification to discern if folk take up If never afterwards the EnterCriticalSection ambition allow the calling thread into the bathroom If the bathroom has been occupied afterwards the calling thread must be waiting outdoor If a person is using the bathroom he have to take the bathrooms to one unoccupied state LeaveCriticalSection tells the system that it has left the resources occupied at If you forget to call LeaveCriticalSection the system will all reserve waiting to enter the lavatory folk waiting outdoor Critical section deserving to the internal use of Interlock array function therefore perform very fast It is never the shortcomings among the process of synchronization between threads While the signals and events can be General CRITICAL_SECTION structure as universal variables to distribution so among the process of all threads are accessible through the variable to direction these structures Actual use this architecture as a local variable allocated from the heap alternatively private members of the class are likewise can But there are two necessary conditions :First :to way resources thread must know to way resources architecture of the CRITICAL_SECTION addresses Second :in any of the threads to path the protected resource ahead have to be on the architecture of CRITICAL_SECTION initialization Initialization call :VOID InitializeCriticalSection ( PCRITICAL_SECTION PCs ) ;this function sets the CRITICAL_SECTION architecture of some members If these members have never been initialized the sequel aspiration be unpredictable When the thread does not need to path the shared resource ought call the following function to clean up the building of CRITICAL_SECTION : VOID DeleteCriticalSection ( PCRITICAL_SECTION PCs ) ;in the course to a shared resource to call EnterCriticalSection this function aspiration perform the following actions: 1 :if there namely not threads in the course to the resource the function will update the membership variables that the thread has gained path to a resource right and the updating of the calling thread is allowed to access number A thread can continue two :if you have some other thread occupying the resource the function ambition use one event kernel objects to the calling thread switching to a await state When the take-up thread calls to LeaveCriticalSection the system ambition automatically update the CRITICAL_SECTION membership variables and the suspended thread switching to an operation state In order to prevent other threads meantime resources are occupied main thread namely suspended you can call the TryEnterCriticalSection function this function ambition detect the main thread can path shared resources If the resources are occupied the function returns false Otherwise it returns true If it namely detected that the resources along this period is occupied main thread which namely capable of doing other things instead of being suspended Because the TryEnterCriticalSection function aspiration update the CRITICAL_SECTION architecture of some members thus requiring a corresponding LeaveCriticalSection function Lock peruse write ( RWLock ) to peruse and jot bolt can also be a resources protection But it is vary with the key section bolt read mark allow us to distinguish between those who lack to read the resources and alteration the resource thread thread Let all the reading resources thread work simultaneously is feasible as reads aspiration not crash data Only meantime writing only need to mark thread synchronization Write the thread have to be preferential resources it is either a read alternatively jot thread must await as Lock peruse write forward use absence to allocate a structure of SRWLOCK called InitializeSRWLock and initialize it Void InitializeSRWLock ( PSRWLOCK SRWLock ) ;after the initialization is done the inventor thread can call AcquireSRWLockExclusive SRWLock thing address incoming to donation preferential access to protected resources Void AcquireSRWLockExclusive ( PSRWLOCK SRWLock ) ;exclusive path after the abolish need to call ReleaseSRWLockExclusive :Void ( PSRWLOCK SRWLock ) ;lift the exclusive resources For the reader thread by calling AcquireSRWLockShared :Void ( PSRWLOCK SRWLock ) ;access to shared course to resources Void ReleaseSRWLockShared ( PSRWLOCK SRWLock ) ;released aboard resource sharing Lock peruse mark never for much times repeatedly writing resources locked resources then calls ReleaseSRWLock* to release the bolt aboard the resource Multiple threads can guide to some synchronization overhead If you use a alone thread course to a resource needs XMS it uses two threads spend time ambition be &gt ;2x Because in addition to the synchronization overhead there are a digit of CPU have to communicate with every other to maintain storeroom coherency Cpu numeral more which takes more Lock read jot perform a peruse operation namely better than a jot operation This is as the two threads can be read in the meantime merely needs to be written at a time when only one writing Comparison of revise thread synchronization methods peruse and jot bolt and opener duration of similar performance in some cases to read and mark lock alternatively even better only likewise allows multiple threads simultaneously peruse It namely recommended to use to peruse and write bolt Using mutex performance is worst This namely for the waiting as the mutex and afterward release the mutex absence thread called API which among corner ambition outcome within the consumer mode and nucleus mode In the then part describes the use of nucleus entity synchronization namely also introduced Use of the peruse and jot lock can also solve the maker consumer problem If the reader thread not data readable it ought be a bolt release and waiting until the producers to jot present data If the author longing buffer fraught it likewise ought release the bolt and goes to doze To accomplish such a thread synchronization namely quite intricate windows provides us with some function simplifies the operation Windows provides the SleepConditionVariableCS or SleepConditionVariableSRW function await condition variables Threads waiting to the variable conditions aspiration atomically bolt release and the obstruction until the condition variable namely triggered Bool SleepConditionVariableCS ( PCONDITION_VARIABLE pConditionVariable PCRITICAL_SECTION pCriticalSection DWORD dwMilliseconds ) ;Bool SleepConditionVariableSRW ( PCONDITION_VARIABLE pConditionVariable PSRWLOCK pSRWLock DWORD dwMilliseconds ULONG Flags ) ;pConditonVariable point to a to initialize the condition variable the calling thread longing await for the condition variables Second parameters to a fussy section alternatively the SRWLock object The key section alternatively SRWLock acclimate to synchronize access to shared resources Flags specifies once condition variable namely triggered the thread ambition be ways to get lock On the reader thread ought be passed to the CONDITION_VARIABLE_LOCKMODE_SHARED expressed the wish that the shared course to a resource The lyricist thread ought pass among 0 said preferential resource DwMilliseconds said we hope threads spend much phase waiting condition is triggered At the appointed phase runs out whether the condition variable has never been triggered the function returns artificial alternatively true When another thread corresponding to the detected condition has been met such as the existence of an element can acquaint the reader thread to peruse It aspiration call the WakeConditionVariable or WakeAllConditionVariable the trigger condition variables It calls the Sleep* function blocks among the condition of variable thread is awakened Void WakeConditonVariable ( PCONDITION_VARIABLE ConditionVariable ) ;Void WakeAllConditionVariable ( PCONDITION_VARIABLE ConditionVariable ) ;WakeConditionVariable SleepConditionVariable* aspiration be waiting with a condition variable triggered threads get lock and return No matter how the compiler generated code,seven. 相关的主题文章：

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