shared-memory

In my code I do the following initialization : struct PipeShm myPipe = { .init = 0 , .flag = FALSE , .mutex = NULL , .ptr1 = NULL , .ptr2 = NULL , .status1 = -10 , .status2 = -10 , .semaphoreFlag = FALSE }; int initPipe() { if (!myPipe.init) { myPipe.mutex = mmap (NULL, sizeof *myPipe.mutex, PROT_READ | PROT_WRITE,MAP_SHARED | MAP_ANONYMOUS, -1, 0); if (!sem_init (myPipe.mutex, 1, 0)) // semaphore is initialized to 0 { myPipe.init = TRUE; } else perror ("initPipe"); } return 1; // always successful } I can have multiple processes that can be invoked from main() (note the fork ) . Thanks AFAICS

I am trying to use boost::interprocess to allocate a very simple data structure in shared memory but I cannot quite figure out how to use the boost interprocess allocators to perform the memory allocations/deallocations within the shared memory segment which I allocate as follows using namespace boost::interprocess; shared_memory_object::remove("MySharedMem"); mSharedMemory = std::make_unique<managed_shared_memory>( open_or_create, "MySharedMem", 65536); I previously asked a similar question but unfortunately I never got any answers. MyStruct below is essentially an array with a length field

How do you change the size of the shared memory folder /dev/shm in an App Engine Flexible app? By default it is set to 64M, too low to run many apps (e.g., chrome). I don't see any way to change it. There are ways to change it if you have access to the docker run command , but we don't have such access when launching app engine flexible apps. A: No. Unfortunately this isn't possible (yet?) with appengine. More than a few people have run into this issue. For some reason, the container default for /dev/shm is crazy small. ...but there are other options If the process you want to run has the

I'm a little bit confused about the terminology of Boost Library (for windows). What I'm trying to do is simply; create a file on disk (a big file >50 GB) do some mapping for write and read operations seperately. For example first map 1 gb portion for writing & after that flush it to the hard drive take a new portion and so on, while the reader applications maps different parts of the file and do the reading stuff without changing anything (no edit). I'm reading the documentation of boost (1.47.0 version since we allowed to use this one) and I don't understand exactly when to use Memory Mapped

By examing several DLLs I have in my windows machine (for instance KERNEL32.DLL) I've notice that none of their sections, not even the read only data section have the IMAGE_SCN_MEM_SHARED flag set. DLLs are mapped from the .dll file so only when you read a page of the file it is copied to physical memory but still, if the same page of let's say kernel32.dll is accessed by both process A and process B then the page will exist twice in physical memory. I am asking for the veracity of this last statement. If the .text or the .rodata segment where shared they would get copied to physical memory