So far, this is the only way I've figured out that works:
(defn try-fib [n]
(let [ch (timeout 1000)
th (Thread. #(!! ch (fib n)))
_ (.start th)
answer (!! ch)]
(if answer answer
(do (.stop th) nil
But there are a couple bazillion sources that say you
You can put the computation into a future, and cancel the future after the
timeout.
BTW is it idiomatic to write to the timeout channel? I thought one should
use something like (alts!! [c (timeout 1000)]).
JW
On Wednesday, January 22, 2014 11:30:23 AM UTC+1, puzzler wrote:
So far, this is
On Wed, Jan 22, 2014 at 2:51 AM, Jozef Wagner jozef.wag...@gmail.comwrote:
You can put the computation into a future, and cancel the future after the
timeout.
I experimented with that, but it didn't seem to work. I suspect that
canceling a future doesn't really do what I think it should do.
What is the task doing? If it is in a tight loop, it must check explicitly
whether the interrupt flag is set and abort. If it is waiting on some
resource, it will receive InterruptedException.
Regards,
Praki Prakash
On Wed, Jan 22, 2014 at 11:20 AM, Mark Engelberg
mark.engelb...@gmail.comwrote:
I think the fib example is a good one in the sense that you are dealing
with an already function that takes a long time, and isn't written as a
loop.
But in general, I want to solve the problem for an arbitrary long-running
computation, for example, a call into a library that you don't control.
If you want to be able to control an arbitrary long-running function, a
safe way is to run it in a separate process. That way you can safely
terminate it anytime you want. Of course this opens up a lot of other
issues :)
On Wed, Jan 22, 2014 at 9:15 PM, Mark Engelberg
Is there a convenient way within Clojure to launch a Clojure function or
Java call in a separate process as opposed to a separate thread? Only way
I know of is to literally shell out to the command prompt and launch a new
executable.
On Wed, Jan 22, 2014 at 12:19 PM, Jozef Wagner
On Thursday, 23 January 2014 02:37:43 UTC+5:30, puzzler wrote:
Is there a convenient way within Clojure to launch a Clojure function or
Java call in a separate process as opposed to a separate thread? Only way
I know of is to literally shell out to the command prompt and launch a new
So I guess this gets back to my earlier question: when is it safe to
terminate a thread?
I know that I often hit Ctrl-C in the REPL to terminate a long running
function, and I've never really worried about it screwing things up.
On Wed, Jan 22, 2014 at 1:29 PM, Shantanu Kumar
It's not safe if the thread is holding any locks. It *may* also leak native
resources if the thread is holding those, but native resources held by a
heap-allocated Java object are supposed to be cleaned up by the finalizer
if the object is GC'd, and I think Thread.stop properly removes that
For processes, there is a https://github.com/Raynes/conch but I haven't
used it yet so I don't know how mature it is.
On Wed, Jan 22, 2014 at 10:45 PM, Cedric Greevey cgree...@gmail.com wrote:
It's not safe if the thread is holding any locks. It *may* also leak
native resources if the thread
I took a stab at it in pure core.async, unfortunately, it does not work; I
would be curious if anyone could explain why.
(use '[clojure.core.async :only [timeout ! go !! alts!]])
(defn fib [n tmout]
(let [res (go (if ( n 2)
n
(let [r1 (! (fib (- n 1)
Consider the really slow fib function:
(defn fib [n]
(if ( n 2) n (+ (fib (dec n)) (fib (- n 2)
Now, let's say I want to compute the fib of some number n and timeout and
return nil if it takes longer than a second.
(defn try-fib [n]
(let [ch (timeout 1000)]
(go (! ch (fib n)))
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