gzdeflate and file_get_contents memory leak?

I have a download script that streams the contents of multiple files into a zip archive before passing it on the to browser to be downloaded.  The script uses file_get_contents() and gzdeflate() to loop over multiple files to create the archive.  Everything works fine, except I have noticed that for a large number of files, this script will exceed the php memory limit.  I have used memory_get_peak_usage() to narrow down the source of the high memory usage and found it to be the two above methods.  The methods are used in a loop and the variable containing the file data is unset() and not referenced in between calls.  The script peak memory usage for the script should be a function of the single largest file that is included in the archive, but it seems to be the aggregate of all files. Here is the pseudo-code for this loop: header( /* specify header to indicate download */ ); foreach( $files as $file ) { echo zip_local_header_for($file); $data = file_get_contents( $file )   $zdata = gzdeflate( $data ); unset($data); unset($zdata); } echo zip_central_dir_for($files); If I remove either the gzdeflate and replace the file_get_contents() with a fread() based method, the script no longer experiences memory problems. Is this behavior as designed for these two functions (because PHP scripts are usually short lived)? Is there a way to get them to release memory? Is there something I'm missing? Thanks. -- Ryan