专业网站建设优势,企业管理网课,Seo建设网站的步骤,怎么样免费做网站为什么用rsync删除大量文件的时候比用rm快今天研究怎么在Linux下快速删除大量文件#xff0c;搜到很多人都说可以用rsync来删除大量文件#xff0c;速度比rm要快很多#xff0c;但是没有人说为什么#xff0c;仔细研究了一下原因#xff0c;总结起来大概就是#xff0c;一…为什么用rsync删除大量文件的时候比用rm快今天研究怎么在Linux下快速删除大量文件搜到很多人都说可以用rsync来删除大量文件速度比rm要快很多但是没有人说为什么仔细研究了一下原因总结起来大概就是一个是列出文件的时候在文件非常多的时候会导致慢 另外就是删除导致B树rebanlance导致开销rsync减少了这种开销所以速度比rm要快转rm on a directory with millions of filesWhen a directory needs to be listed readdir() is called on thedirectory which yields a list of files. readdir is a posix call,but the real linux system call being used here is calledgetdents. Getdents list directory entries by filling a buffer isentries.The problem is mainly down to the fact that that readdir()uses a fixed buffer size of 32Kb to fetch files. As a directorygets larger and larger (the size increases as files are added) ext3gets slower and slower to fetch entries and additional readdirs32Kb buffer size is only sufficient to include a fraction of theentries in the directory. This causes readdir to loop over and overand invoke the expensive system call over and over.。。。。I revisited this today, because most filesystems store theirdirectory structures in a btree format, the order of which youdelete files is also important. One needs to avoid rebalancing thebtree when you perform the unlink.As such I added a sort before deletes occur. The program willnow (on my system) delete 1000000 files in 43 seconds. The closestprogram to this was rsync -a --delete which took 60 seconds (whichalso does deletions in-order, too but does not perform an efficientdirectory lookup).Efficiently delete large directory containing thousands offileslinux-快速删除五十万文件的方法linux下面快速删除大量文件及快速复制大量小文件
