major performance problem with gcc2 version of STL

[augiedoggie]

There seems to be a problem with the gcc2 version of std::ostringstream. In certain cases the gcc2 version is up to 300 times slower than with gcc4. I'm attaching some sample code which demonstrates the problem.

[augiedoggie]

Apparently this is a known problem with many versions of the stl. The problem is that ostringstream only increases the buffer by a very small amount at a time(1 char?) which causes a lot of allocations and memory copies.

The problem code with our headers is at: ​http://dev.haiku-os.org/browser/buildtools/trunk/legacy/gcc/libstdc++/sstream#L109

The line that reads:

stream_len += 1;

should probably be replaced by something which examines the length of the incoming buffer similar to what the gcc4 version does.

[augiedoggie]

This ticket can be closed. After combing through many bug reports on the subject it seems the only solution was to replace libstdc++ with a newer version which would probably break binary compatibility for us.