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 test
cd test
mkdir da
echo foo > da/foo
echo foo > foo
hg ci -Ambase -d '0 0'
hg serve -p $HGPORT -d --pid-file=hg.pid
echo % manifest
("$TESTDIR/get-with-headers.py" localhost:$HGPORT '/file/tip/?style=raw')
("$TESTDIR/get-with-headers.py" localhost:$HGPORT '/file/tip/da?style=raw')
kill `cat hg.pid`