Re: Cygwin can't handle huge packfiles?

Hi,

On Mon, 3 Apr 2006, Kees-Jan Dijkzeul wrote:

I'm trying to get Git to manage a 5Gb source tree. Under linux, this
works like a charm. Under cygwin, however, I run in to difficulties.
For example:

$ git-clone sgp-wa/ sgp-wa.clone
fatal: packfile
./objects/pack/pack-56aa013a0234e198467ed37ae5db925764a6ee98.pack
cannot be mapped.
fatal: unexpected EOF
fetch-pack from '/cygdrive/e/Projects/sgp-wa/.git' failed.

To figure out what is happening, I printed the value of errno, which
turns out to be 12 (Cannot allocate memory). I'm not sure how mmap is
implemented in cygwin, but if they allocate memory and load the file
into it, then this error is not surprising, as the pack file in
question is 1.5Gb in size.

The problem is not mmap() on cygwin, but that a fork() has to jump through 
loops to reinstall the open file descriptors on cygwin. If the 
corresponding file was deleted, that fails. Therefore, we work around that 
on cygwin by actually reading the file into memory, *not* mmap()ing it.

Hth,
Dscho