Phusion Passenger 4.0.57: better Ruby 2.2 support, Nginx 1.7.9 support

We've just released version 4.0.57 of the Phusion Passenger application server for Ruby, Python and Node.js. This release fixes two minor but important issues.

Phusion Passenger 4 is the current stable branch, in which we release bug fixes from time to time. At the same time there is also Phusion Passenger 5, which is the not-yet-ready-for-production development branch, with major changes and improvements and terms of performance application behavior visibility. Version 5.0 beta 3 will soon be released, but until the 5.x branch is considered stable, we will keep releasing bug fixes under the 4.x branch.

Phusion Passenger also has an Enterprise version which comes with a wide array of additional features. By buying Phusion Passenger Enterprise you will directly sponsor the development of the open source version.

Improved Ruby 2.2 support

Version 4.0.56 already introduced Ruby 2.2 support, but due to an issue in the way we compile the Phusion Passenger native extension, it didn't work with all Ruby 2.2 installations. In particular, 4.0.56 worked with Ruby 2.2 installations that were compiled with a shared libruby, which is the case if you installed Ruby 2.2 with RVM or though operating system packages. But it did not work with Ruby 2.2 installations that were compiled with a static libruby, which is the case if you installed manually from source, or using rbenv and chruby, or when you are using Heroku.

At first, we suspected a bug in Ruby 2.2's build system, but after feedback from the MRI core developers, it turned out to be an issue in our own build system. The issue is caused by a commit from 4 years ago, GH-168, which attempted to fix a different issue. It seems there is no way to fix Ruby 2.2 compatibility while at the same time fixing GH-168, so we had to make a choice. Since GH-168 is quite old and was made at a time when Ruby 1.8.6 was the latest Ruby version, we believe that the issue is no longer relevant. We reverted GH-168 in favor of Ruby 2.2 compatibility.

Many thanks to the different users who have supplied feedback. You can read the discussions at the Github issue tracker.