revlog: break up compression of large deltas Python's zlib apparently makes an internal copy of strings passed to compress(). To avoid this, compress strings 1M at a time, then join them at the end if the result would be smaller than the original. For initial commits of large but compressible files, this cuts peak memory usage nearly in half.

#!/bin/sh

hg init repo
cd repo
touch foo
hg add foo
for i in 0 1 2 3 4 5 6 7 8 9 10 11; do
    echo "foo-$i" >> foo
    hg ci -m "foo-$i" -d "0 0"
done

for out in "%nof%N" "%%%H" "%b-%R" "%h" "%r"; do
    echo "# foo-$out.patch"
    hg export -v -o "foo-$out.patch" 2:tip
done