3 Occasionally odd {issues}[link:ISSUES.html] arise without a transparent or
4 acceptable solution. Those issues are documented here.
6 * For notes on sandboxing tools such as Bundler or Isolate,
7 see the {Sandbox}[link:Sandbox.html] page.
9 * nginx with "sendfile on" under FreeBSD 8 is broken when
10 uploads are buffered to disk. Disabling sendfile is required to
11 work around this bug which should be fixed in newer versions of FreeBSD.
13 * Under Ruby 1.9.1, methods like Array#shuffle and Array#sample will
14 segfault if called after forking. This is fixed in trunk (r26936) and
15 should be backported to the next 1.9.1 stable release (after p378).
16 Until then, it is advisable to call "Kernel.rand" in your after_fork
17 hook to reinitialize the random number generator.
19 See http://redmine.ruby-lang.org/issues/show/2962 for more details
21 * When using "preload_app true", with apps using background threads
22 need to restart them in the after_fork hook because threads are never
23 shared with child processes. Additionally, any synchronization
24 primitives (Mutexes, Monitors, ConditionVariables) should be
25 reinitialized in case they are held during fork time to avoid
26 deadlocks. The core Ruby Logger class needlessly uses a MonitorMutex
27 which can be disabled with a {monkey patch}[link:examples/logger_mp_safe.rb]
29 * Rails 2.3.2 bundles its own version of Rack. This may cause subtle
30 bugs when simultaneously loaded with the system-wide Rack Rubygem
31 which Unicorn depends on. Upgrading to Rails 2.3.4 (or later) is
32 strongly recommended for all Rails 2.3.x users for this (and security
33 reasons). Rails 2.2.x series (or before) did not bundle Rack and are
34 should be unnaffected. If there is any reason which forces your
35 application to use Rails 2.3.2 and you have no other choice, then
36 you may edit your Unicorn gemspec and remove the Rack dependency.
38 ref: http://mid.gmane.org/20091014221552.GA30624@dcvr.yhbt.net
39 Note: the workaround described in the article above only made
40 the issue more subtle and we didn't notice them immediately.
42 * WONTFIX: code reloading and restarts with Sinatra 0.3.x (and likely older
43 versions) apps is broken. The workaround is to force production
44 mode to disable code reloading as well as disabling "run" in your
48 Since this is no longer an issue with Sinatra 0.9.x apps, this will not be
49 fixed on our end. Since Unicorn is itself the application launcher, the
50 at_exit handler used in old Sinatra always caused Mongrel to be launched
51 whenever a Unicorn worker was about to exit.
53 Also remember we're capable of replacing the running binary without dropping
54 any connections regardless of framework :)