added some more information about Mojo::IOLoop scalability

mojolicious · May 2, 2014 · 949ef4b · 949ef4b
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diff --git a/Changes b/Changes
@@ -1,5 +1,5 @@
 
-4.98  2014-05-02
+4.98  2014-05-03
   - Removed deprecated get_line function from Mojo::Util.
   - Removed deprecated content_xml, replace_content, text_before, text_after
     and to_xml methods from Mojo::DOM.

diff --git a/lib/Mojo/IOLoop.pm b/lib/Mojo/IOLoop.pm
@@ -299,6 +299,17 @@ L<Mojo::IOLoop> is a very minimalistic event loop based on L<Mojo::Reactor>,
 it has been reduced to the absolute minimal feature set required to build
 solid and scalable non-blocking TCP clients and servers.
 
+Note that depending on operating system, the default per-process and
+system-wide file descriptor limits are often very low and need to be tuned for
+better scalability. The C<LIBEV_FLAGS> environment variable should also be
+used to select the best possible L<EV> backend, which usually defaults to the
+not very scalable C<select>.
+
+  LIBEV_FLAGS=1   # select
+  LIBEV_FLAGS=2   # poll
+  LIBEV_FLAGS=4   # epoll (Linux)
+  LIBEV_FLAGS=8   # kqueue (*BSD, OS X)
+
 The event loop will be resilient to time jumps if a monotonic clock is
 available through L<Time::HiRes>. A TLS certificate and key are also built
 right in, to make writing test servers as easy as possible. Also note that for