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Posted on 14 Мар 201819

Github - cgaebelpipe a simple thread-safe fifo in c

Github - cgaebelpipe a simple thread-safe fifo in c
Since the two processes are decoupled by a fast in-memory pipe (which is implemented with simple memcpy's), when one thread lags behind, the other one is free to continue its operation. If the producer is lagging, the consumer will block until there is data. If the consumer is lagging, requests will just pile up in the queue to .

Tweaking --------------- There are a few things you can do to get the most speed out of the pipe. For example, the Actor model has no explicit locking at all. Emptying the pipe frequently tends to be faster and use less memory. NUMTHREADS 20 /* number of threads to create */ typedef struct node node; typedef struct queue queue; struct node { char *name; node *next; }; struct queue { node *head; node *tail; }; /* pop: remove and return first name from a queue */ char *pop(queue *q) { if (q->head == NULL) return NULL; char *name = q->head->name; node *tmp = q->head; q->head = q->head->next; free(tmp); return name; } /* push: add name to the end of the queue */ int push(queue *q, char *name) { node *new = malloc(sizeof(node)); if (new == NULL) return -1; new->name = name; new->next = NULL; if (q->tail != NULL) q->tail->next = new; q->tail = new; if (q->head == NULL) /* first value */ q->head = new; return 0; } /* printname: get a name from the queue, and print it. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. I have used multithreading library before in Python, but this is the first time I am trying threading in C. In the disk thread, it will read from the pipe, dumping any data onto the disk *without blocking the networking thread*. It is not thread-safe since multiple threads may modify the pointers in the linked list at the same time, potentially corrupting it. It implements the queue with a single god-mutex which is simple in practice, but is not the most concurrent design decision.

In turn, these workers supposed to push to or pop from queue. If you have successfully tested it on any of these, feel free to let me know by dropping me an email Microsoft Windows 7 If you _must_ use Windows, try to only support windows Vista and onwards. Imagine we had a locking mechanism whereby threads could synchronize their behaviour, such that only one thread at a time could execute the code in the lines 1 to 4, e. If you are always pushing predictable amounts of data into the pipe (such as 1000 elements at a time), you should consider using `pipe_reserve` to keep the pipe from needlessly growing and shrinking. When the disk starts spinning up, you don't want your download to slow down! To solve this problem, we introduce a new data structure called a pipe. Feel free to set it to zero to disable spin locking altogether and just use the native lock implementation. NULL) pthread_exit(NULL); printf("%s\n",name); pthread_exit(NULL); } int main() { size_t i; int rc; pthread_t threads[NUMTHREADS]; char *names[] = { "yasar", "arabaci", "osman", "ahmet", "mehmet", "zeliha" }; queue *q = malloc(sizeof(queue)); q->head = NULL; q->tail = NULL; /* number of elements in the array */ size_t numelems = sizeof(names) / sizeof(char *); for (i = 0; i < numelems; i++) /* push each name */ push(q, names[i]); for (i = 0; i < NUMTHREADS; i++) { /* fire up threads */ rc = pthread_create(&threads[i], NULL, printname, (void *)q); if (rc) { printf("Error, return code from pthread is %d\n", rc); exit(-1); } } pthread_exit(NULL); } I tried above code, and it always printed each name exactly once. If you can combine a whole bunch of elements into a single struct, it will be faster to push and pop one large struct at a time rather than a push/pop of many small structs. No matter how many producers or consumers you have, pipe will behave predictably (although not necessarily fairly). C is so pervasive, I hope to see these concepts leaking into other languages and libraries, hopefully being expanded upon and becoming a building block of the next generation of concurrent programming.

Github - petercronastsqueue simple thread safe queue in c
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- The code is not thread safe. The push and pop functions are not thread safe. In the code, the push is only being executed by a single thread, so it doesn't matter, but the pops are being executed by multiple threads. Char *name = q->head->name; 2. Node *tmp = q->head; 3.

GNU/Linux i686 * GNU/Linux x86-64 * Windows 7 x64 (Cross-compiled from GNU/Linux with mingw64) * Windows 7 (Compiled with mingw) * Windows 7 i686 (Cygwin) * OSX 10. Use it! Concurrency Specifications --------------------------- For more details on this list, see: Type of queue: Multi-producer/Multi-consumer Underlying data structure: Array-based Maximum size: Bounded/Unbounded can be selected at runtime Overflow behavior: Block until there is room Requirement for garbage collection: None Support for priorities: No Ordering guarantees: per-producer FIFO Behavior on empty queue: Block until elements arrive Compatibility -------------- pipe. Tweaking --------------- There are a few things you can do to get the most speed out of the pipe. If the producer is lagging, the consumer will block until there is data. If you want to use pipe in your code, you want to checkout this branch.

Emptying the pipe frequently tends to be faster and use less memory. Avoid limiting the size of the pipe unless you get serious memory issues. Promise! Things I'd love to see are speed improvements (especially those which reduce lock contention), support for more compilers/platforms, a better makefile (the current one is pitiful), and any algorithmic improvements. Imagine thread A executes up to and including line 2. It is not enough merely to sychronize execution; at the same time, we must also ensure the writes performed by a core become visible to other cores. Read through the source code, and find bottlenecks! Don't forget to submit changes upstream, so the rest of the world can be in awe of your speed-hackery. On the other hand, I am not sure how thread safe this queue implementation is. It is "done" in terms of the only new code going into it is bugfixes and performance tweaks. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. GitHub is home to over 20 million developers working together to host and review code, manage projects, and build software together. NUMTHREADS 20 /* number of threads to create */ typedef struct node node; typedef struct queue queue; struct node { char *name; node *next; }; struct queue { node *head; node *tail; }; /* pop: remove and return first name from a queue */ char *pop(queue *q) { if (q->head == NULL) return NULL; char *name = q->head->name; node *tmp = q->head; q->head = q->head->next; free(tmp); return name; } /* push: add name to the end of the queue */ int push(queue *q, char *name) { node *new = malloc(sizeof(node)); if (new == NULL) return -1; new->name = name; new->next = NULL; if (q->tail != NULL) q->tail->next = new; q->tail = new; if (q->head == NULL) /* first value */ q->head = new; return 0; } /* printname: get a name from the queue, and print it. When the disk starts spinning up, you don't want your download to slow down! To solve this problem, we introduce a new data structure called a pipe. It is not thread-safe since multiple threads may modify the pointers in the linked list at the same time, potentially corrupting it. I have used multithreading library before in Python, but this is the first time I am trying threading in C.

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