memory-mapped-files

问题 Please excuse me if this is a poor question as I am not good with memory mapped files. I am using memory mapped files in my project. I am tracking the files in progress and the file that has already processed in memory mapped files. I have two memory mapped files. In the first memory mapped file, I keep track of processed files and in the second memory mapped file, I keep track of files under processing. So when the processing is complete on a particular file, I make an entry in the first

问题 Please excuse me if this is a poor question as I am not good with memory mapped files. I am using memory mapped files in my project. I am tracking the files in progress and the file that has already processed in memory mapped files. I have two memory mapped files. In the first memory mapped file, I keep track of processed files and in the second memory mapped file, I keep track of files under processing. So when the processing is complete on a particular file, I make an entry in the first

问题 Background : in Java I'm memory mapping a file (shared). I'm writing some value at the address 0 of that file. I understand the corresponding PAGE in the PAGE CACHE is flagged as DIRTY and will be written later depending on the dirty_ratio and the like settings. So far so good. But I'm wondering what is happening when writing once more at the address 0 while the kernel is writing back the dirty page to the file. Is my process blocked somehow waiting for the writeback to be completed? 回答1: It

问题 Background : in Java I'm memory mapping a file (shared). I'm writing some value at the address 0 of that file. I understand the corresponding PAGE in the PAGE CACHE is flagged as DIRTY and will be written later depending on the dirty_ratio and the like settings. So far so good. But I'm wondering what is happening when writing once more at the address 0 while the kernel is writing back the dirty page to the file. Is my process blocked somehow waiting for the writeback to be completed? 回答1: It

问题 I'm writing windows program with C and Visual Studio. I have to map a file than access it from it's 750th byte. I tried pFile = (char *) MapViewOfFile(hMMap,FILE_MAP_ALL_ACCESS,0,(DWORD) 750,0) open file with this but it returns error 1132. ERROR_MAPPED_ALIGNMENT 1132 (0x46C) The base address or the file offset specified does not have the proper alignment. How can resolve this? 回答1: The documentation of MapViewOfFile is pretty clear that the offset has to be a multiple of the allocation

问题 Exactly as the question says. I want to use shared memory to communicate between two lisp processes. Any pointers on how to do that? I can see some tutorials on doing this in clozure at :- http://ccl.clozure.com/manual/chapter4.7.html Can someone point me to a similar library to do this with sbcl? 回答1: For a portable implementation, you might want to use the osicat library, which provides a CFFI wrapper for many POSIX calls in the osicat-posix package. There is a very nice and short article

问题 I am memory mapping a large file (~200GB) into a single region/view and sequentially writing to it. Every now and then I perform a boost::interprocess::mapped_region::flush(last, current, false) . After a while the process uses up the entire system memory. Which, from what I understand, is normal as it will be releasing the memory as other process request memory. This works well on Windows 8. However, running on Windows 7 it doesn't seem to play well with the drivers for AJA video cards and

问题 I try to write following struct to a memory mapped file, but I still have problem with the array (writing throws exception that the struct can not contain reference) [StructLayout(LayoutKind.Explicit)] struct IndexEntry { [FieldOffset(0)] public byte key; [FieldOffset(4)] public int lastValueIdx; [FieldOffset(8)] [MarshalAs(UnmanagedType.ByValArray, SizeConst = Constants.PART_ENTRY_SIZE)] public long[] values; } I use this calling for writing: UnmanagedMemoryAccessor.Write<IndexEntry>(0, ref

问题 Lest I provide an XY problem, my goal is to share a memory-mapped file between multiple goroutines as recommended. Each goroutine needs to iterate over the file line by line so I had hoped to store the complete contents in memory first to speed things up. The method I tried is passing a pointer to a bufio.Scanner , but that is not working. I thought it might be related to needing to set the seek position back to the beginning of the file but it is not even working the very first time and I

问题 We need to share very efficiently block of constantly changing information between two processes. Information fits in 64bits block of memory - so inside one process we'd be able to use Interlocked operations (or probably even just ordinary reads/writes) to ensure lock-free access to correct state of information (not just partially written). How can we write and ready block of 64bit data into MMF without locking and synchronization in order to make sure that we don't read partially written