svnwrap: use custom StringIO class in get_file() The wrappers were calling ra.get_file() with a cStringIO object. Empirically, svn 1.7.5 is writing 16kB blocks to the stream object, and cStringIO reallocates its internal buffer and doubles its size whenever it is filled. With large committed files this requires two large memory blocks at the same time. SimpleStringIO implements the mimimum StringIO interface used by ra.get_file() but instead stores all the blocks and "join" them at the end. It means more fragmentation but requires only one large block, without overallocation. Also, 16kB blocks should be friendly to most allocators. In practice, this simple change let me convert a revision containing multiple moderately large files, the largest being around 450MB, with a 32-bits Windows setup, python 2.7, swig svn 1.7.5, in stupid mode, while it was previously aborting with "not enough memory". The same revision still fails in replay mode.

#!/bin/sh
#
# Generate mergeexternals.svndump
#

mkdir temp
cd temp

mkdir project-orig
cd project-orig
mkdir trunk
mkdir branches
cd ..

svnadmin create testrepo
svnurl=file://`pwd`/testrepo
svn import project-orig $svnurl -m "init project"

svn co $svnurl project
cd project/trunk
mkdir d1
echo a > d1/a
mkdir d2
echo b > d2/b
mkdir -p common/ext
echo c > common/ext/c
svn add d1 d2 common
svn ci -m addfiles
svn up
svn propset svn:externals '^/trunk/common/ext ext' d1
svn propset svn:externals '^/trunk/common/ext ext' d2
svn ci -m addexternals
cd ..
svn up
svn cp trunk branches/branch
cd branches
svn ci -m addbranch
cd branch
mkdir d3
echo d > d3/d
svn add d3
svn propset svn:externals '^/trunk/common/ext ext3' d3
svn ci -m touchbranch
cd ../../trunk
svn merge '^/branches/branch'
svn up
svn ci -m 'merge'
cd ../..

svnadmin dump testrepo > ../mergeexternals.svndump