logo
Tags down

shadow

Waiting on multiple semaphores or multiple message queues


By : user2174456
Date : October 18 2020, 08:10 AM
I hope this helps you . ,
Is there a better way to handle this?
code :


Share : facebook icon twitter icon

Waiting on multiple semaphores without busy-waiting (C/C++ Linux)


By : user3650598
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , Here (developers.sun.com, via the Internet Archive) is a short paper from Sun about how they implemented their WaitForMultipleObjects emulation in Solaris. The basic idea is to associate a list of condition variables to a handle (protected by a mutex), and signal all of the condition variables whenever the handle is signaled. Each time you call the emulated WaitForMultipleObjects, a new condition variable is created and added to the list of all handles you are interested in. In the WaitForMultipleObjects emulation, you block on the condition variable, and check each of your handles when you wake up.
The reason why there is a list of condition variables (and not a single one) is that you may have two threads blocking on handles: thread 1 is blocked on A and B, and thread 2 is blocked on A and C. Signaling B should not wake up thread 2. Since each call to WaitForMultipleObjects create a new condition variable, in this scenario, B and C will have one distinct condition variable each, and A will have both condition variables.

Linux Message Queues - Multiple receivers


By : 许思涵
Date : March 29 2020, 07:55 AM
will be helpful for those in need The short answer is that the kernel decides.
The long answer is that this is handled by the do_msgrcv() call within the Linux kernel. If there is no message available, the caller gets put on a queue until a message is available. It's not guaranteed to go back and forth like you describe, since it all depends on the timing of each msgrcv() call, but in your case, it will probably behave that way virtually all of the time.

s3 - file uploaded - message in multiple sqs queues


By : Andy Zhao
Date : March 29 2020, 07:55 AM
it fixes the issue You can configure a SNS topic which will get the message when there is a upload to s3 bucket.
Then subscribe all the SQS queues to that SNS topic. See this.

Creation of Multiple Message Queues, with Unique Keys for the queues


By : Liam
Date : March 29 2020, 07:55 AM
it should still fix some issue We create multiple queues for message passing from one process to other. But sometimes the keys of the message queues get overlapped ( same keys for separate queues). In order to avoid this I thought of using IPC_PRIVATE with the function msgget() which is used in the creation of Message queues. ,
Please tell me the syntax for msgget with IPC_PRIVATE
code :
int flags = /* ... permission bits ... */;
int my_mq = msgget(IPC_PRIVATE, flags);

Propagating message's through multiple queues


By : Hendra Aditya
Date : March 29 2020, 07:55 AM
I wish this helpful for you When you think about propagation, it's kinda logical that when you propagate message to another queue, it enqueue's it to that queue and that should trigger propagation to third queue. However, when you better think about how propagation works, it's kinda logical that propagation to third queue shouldn't get triggered. If you do not specify recipients during enqueue proccess of the message, propagation takes default agents that is subscribed to that aq table and sends messages to them, so it enqueues message to second queue with recipient being that queue, and so message cannot be propagated to third queue because that queue is not a recipient. Workaround for this would be adding callback procedure for when message is enqueued to second queue to dequeue that message and enqueue it to third queue. Or simply creating a job, that would run every couple of seconds, dequeue new messages and enqueue them to third queue.
If i am wrong about this please, let me know.
Related Posts Related Posts :
  • Why does this program for checking if a line is a palindrome return a segfault?
  • How add a message optional parts in the ASN.1 generated C codes
  • How to use mutex in multithreading with C on Linux
  • Problem compiling C/Fortran code together with pgi on windows: "main already defined"
  • How does printf %f work on a 32-bit float
  • Segmentation fault when opening files
  • UARTs & Registers
  • trying to understand recursion in C
  • Why in a bidimensional static array arr, arr is the same thing as *arr
  • How can we produce the number x.y, where x and y are the two arguments or a function?
  • What does printf return c but getting an error
  • C, dividing a string in half
  • How can resort a string array in C using pointers only
  • warning: assignment makes pointer from integer without a cast [-Wint-conversion]
  • Passing typedef function pointer as an argument problem
  • Checking 5 ints in an array if 3 are the same
  • Conflicting types error and pointer from integer without cast warning C
  • Simple IF Else, but crashes the Command Box when I try to generate an error
  • MACRO execution steps in C
  • How to save pointer in JavaScript and retrieve further
  • Value of local static variable changes between function calls
  • Invalid number comes when accessing member structures
  • C program forcing me to have return type but I don't need it.!
  • fgets reads newline character from prompt
  • shadow
    Privacy Policy - Terms - Contact Us © voile276.org