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@@ -85,22 +85,41 @@
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   return Qnil;
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 }
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+const struct timeval idle_timeout = { tv_sec: 0, tv_usec: 50000 };
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+
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 static void
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 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) {
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+  /* How to let other Ruby threads run while we're in this blocking C call */
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+
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+  /* TODO: For Ruby 1.9 I should use rb_thread_blocking_region() instead of 
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+   * this hacky idle_cb
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+   */
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+  
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   if(clients_in_use_p()) {
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+    /* If ruby has control of any clients - that means there are some requests
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+     * still being processed inside of threads. We need to allow Ruby some
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+     * time to work on these threads so we call rb_thread_schedule()
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+     * I don't use rb_thread_select() here because it is very slow.
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+     */
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     rb_thread_schedule();
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+
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   } else if(!rb_thread_alone()) {
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-    /* if you have another long running thread running besides the ones used
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-     * for the webapp's requests you will run into performance problems in 
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-     * ruby 1.8.x because rb_thread_select is slow. 
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-     * (Don't worry - you're probably not doing this.)
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+    /* If no clients are in use, but there are still other Ruby threads then
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+     * some other thread is running in the Ruby VM which is not a request.
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+     * This is a sub-optimal situation and we solve it by calling 
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+     * rb_thread_select() to wait for the server fd to wake up.
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+     * One should try to avoid entering this state.
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      */
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-    struct timeval select_timeout = { tv_sec: 0, tv_usec: 50000 };
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     fd_set server_fd_set;
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     FD_ZERO(&server_fd_set);
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     FD_SET(server->fd, &server_fd_set);
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-    rb_thread_select(server->fd+1, &server_fd_set, 0, 0, &select_timeout);
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+    rb_thread_select(server->fd+1, &server_fd_set, 0, 0, &idle_timeout);
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   } else {
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+    /* Otherwise there are no other threads. We can detach the idle_watcher
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+     * and allow the server_process_connections() to block until the 
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+     * server fd wakes up. Because we don't use rb_thread_select() this
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+     * is quite fast.
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+     */
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     detach_idle_watcher();
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   }
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 }