Critical section refers to either a piece of code that will run concurrently in several threads accessing global data or resources (requiring synchronisation), or a user-level spinlock combined with a mutex object under the Windows operating system. A critical section in the latter sense is functionally identical to a mutex that it cannot shared with a different process and that it is several orders of magnitudes faster in the non-congested case.
Questions tagged [critical-section]
529 questions
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"Pausing" A Thread With A Property
I have a TThread object and want to be able to start/stop the thread via a button on the main form of the program. I've been looking into ways to do this and so far I have the following ideas:
Terminate and Free the thread when the user clicks stop…
user1970794
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Why do the threads run serially in this console application?
I'm creating an console application which needs to run several threads in order to accomplish a task. My problem is that threads are running one after another (thread1 start -> work -> end and ONLY then start thread2) instead of running all in the…
RBA
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How can I implement a thread-safe list wrapper in Delphi?
I have a list wrapper that maintains two Tstringlists and a TClassList
I need this to be thread safe, such that:
Concurrent writes are not allowed (wait state of some sort should be entered)
Reading while writing (or vice versa) is not allowed…
Graza
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using dispatch_sync as a mutex lock
Here is what I need to do.
I hope dispatch_sync would be the best way to do it using GCD
I have a certain piece of critical section code that is placed in the applicationDidBecomeActive callback in Appdelegate..
I am wrapping up that method inside a…
Mr.Anonymous
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Do I need a fence or barrier or something when mutex locks/unlocks are buried deep in function calls?
I recently learned that compilers will optimize your code by rearranging instructions, and that this can be controlled by using barriers.
IIRC, locking a mutex makes a barrier, and unlocking a mutex also makes a barrier, to keep code inside the…
Verdagon
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Can a Windows CRITICAL_SECTION object be configured to deny recursive access?
By default, a CRITICAL_SECTION object is recursive. Can this behaviour be configured like a pthread mutex to enable or disable recursive thread access?
To clarify in response to the comments: I am referring specifically to a Windows CRITICAL_SECTION…
x-x
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What happen if 2 threads do EnterCriticalSection and thread 1 do DeleteCriticalSection
I am hunting a possible deadlock in my program and im suspecting the following.
What happen if 2 threads at the same time calls EnterCriticalSection and thread #1 calls DeleteCriticalSection right after entering, what happen to thread #2 which is…
user1727542
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Critical Sections leaking memory on Vista/Win2008?
It seems that using Critical Sections quite a bit in Vista/Windows Server 2008 leads to the OS not fully regaining the memory.
We found this problem with a Delphi application and it is clearly because of using the CS API. (see this SO question) …
Francesca
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VC++ 2010: Weird Critical Section error
My program is randomly crashing in a small scenario I can reproduce, but it happens in mlock.c (which is a VC++ runtime file) from ntdll.dll, and I can't see the stack trace. I do know that it happens in one of my thread functions, though.
This is…
dario_ramos
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C++: Concurrency and destructors
Suppose you have an object which can be accesed by many threads. A critical section is used to protect the sensitive areas. But what about the destructor? Even if I enter a critical section as soon as I enter the destructor, once the destructor has…
dario_ramos
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Fair critical section (Linux)
On a multi-threaded Linux application I use a mutex for critical sections. This works very well except for the fairness issue. It can happen that a thread leaving a critical section and re-entering right away does not give any other thread a chance.…
Frank
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When should I use critical sections?
Here's the deal. My app has a lot of threads that do the same thing - read specific data from huge files(>2gb), parse the data and eventually write to that file.
Problem is that sometimes it could happen that one thread reads X from file A and…
pop32
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Why did CRITICAL_SECTION performance become worse on Win8
It seems like CRITICAL_SECTION performance became worse on Windows 8 and higher. (see graphs below)
The test is pretty simple: some concurrent threads do 3 million locks each to access a variable exclusively. You can find the C++ program at the…
Rom098
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Does Mutex call a system call?
CRITICAL_SECTION locking (enter) and unlocking (leave) are efficient because
CS testing is performed in user space without making the kernel system call that
a mutex makes. Unlocking is performed entirely in user space, whereas ReleaseMutex…
Benjamin
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Unable to enter critical section
Why is it imposible to enter critical section without Sleep(1)?
type
TMyThread = class(TThread)
public
procedure Execute; override;
end;
var
T: TMyThread;
c: TRTLCriticalSection;
implementation
procedure TForm1.FormCreate(Sender:…
Snus Mumrik
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