Hey, BrowersUK, some of your objections are just bizarre.
They're not available from Perl.
What
"epoll doesn't work with timers, signals... yes, there are the calls signalfd(), and timerfd_create()... they don't help much"
??? BTW, none of the IO multiplexers (to my knowledge) do anything useful with hard disk files.
"epoll maybe O(1) for event notifications, but it remains O(n) for modifications to the interest set"
you found that a problem in practice? Tell me more...
fast changing, dynamic descriptor sets require many and calls into the kernel for epoll_ctl(), which gets expensive.
"fast" compared to what? compared to the speed of CPUs, or compared to the speed of IO that you're presumably doing on these descriptors in between opening and closing them?
kqueue addresses most of that, but retains one major flaw in modern systems: Per process interest sets.
Now, I haven't actually used kqueue (since that's a BSD thing). But you said "retains", and that's wrong: you can create as many epoll instances (sets) as you like, and monitor them separately (using threads, if you like). Actually, kqueue man page says: 
The kqueue() system call fails if:
     [ENOMEM]    The kernel failed to allocate enough memory for the k
+ernel queue.
     [EMFILE]    The per-process descriptor table is full.
     [ENFILE]    The system file table is full.

[download]
Where does it say "you already have one queue in this process and can't get more"?
Basically, it hasn't caught up with the advent of the multi-core architectures that are now ubiquitous; which means you can't easily split your loads across those multiple cores by using multiple thread running separate event loops.
Sure you can, if that's what you want to do, for some reason...

Really, your points look pretty strange to me, except maybe for adding more than one fd at a time to epoll instance. Well, that looks like it wouldn't be difficult to implement, but it wasn't, so I guess other people didn't feel the need for it either.

In reply to Re^6: Allowing user to abort waitpid by Anonymous Monk
in thread Allowing user to abort waitpid by lab007

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