FIT 14.6.8 – BrotliLeaks

14.6.8 is a maintenance release with improvements, bug fixes and third party updates.

For the folks operating FIT servers, we are happy to finally ship a solution for the „BrotliLeaks“ issue causing excessive memory use due to brotli compression. It turned out that neither mod_brotli nor libbrotli were leaking memory. However, the way libbrotli malloc()s and free()s leaves behind a fragmented heap that libc is not willing to return the OS. With the right parameters, we could tune the allocator to avoid this memory bloat, reducing memory usage by 500 MB per httpd process on Red Hat based systems (and up to 100 MB on Ubuntu or SLES).

From time to time, one needs to clear the HTTP cache, e.g. when resources in the origin change. Instead of deleting all cached files, fitadmin maintenance clearcache --http now sets a reference file that instantaneously invalidates all files. The origin then may send lightweight 304 responses to revalidate the existing caches, resulting in faster warmup while often not a single byte will be retransferred.

After another round of data crunching we have tuned the parameters for our image quality prediction algorithm in order to obtain smaller files with Image Compression.

The changelog provides a thorough list of what has changed.