[Bug-tar] "Cannot open: Too many open files" extraction error with --files-from option tar-1.15.90/91

[Ed Leaver]

Hi Sergey. I have been testing your --files-from option on tar-1.15.90 and tar-1.15.91. Last night I created a test tarfile that apparently causes a failure when extracting many small files to multiple directories in round-robin order. The source tarfile resides on disk.

To do this I have an externally stored table-of-contents for the tarfile, prepared in the order in which files were tarred when the tarfile was created. My extract command then looks like

tar -xzf  archive.tar.gz --files-from=filelist.txt

where filelist.txt has format

-C /dir0
file0
-C /dir2
file2
-C /dir3
file3
-C /dir4
file4
-C /dir0
file5
-C /dir1
file6
etc.

Looking at the actual stderr, the errors look like
tar: html/group__pangommEnums.html: Cannot open: Too many open files
tar: Skipping to next header
tar: html/group__PatternMatching.html: Cannot open: Too many open files
tar: Skipping to next header
tar: html/group__Random.html: Cannot open: Too many open files

...and so on. I do not see this problem if I do not use --files-from and just extract everything to one directory.  The problem also appears to be related to many small (1-10KB) files being extracted round-robin, so it may be a timing issue of some sort. I'm probably capable of doing a bit of test&debug myself, but would certainly appreciate a clue as to where to start. Thanks!