On 4/2/13 1:07 PM, Danny Munera wrote:
Hello Vijay,
Thank you for your fast reply.
I have implemented the code that you send me, but I have yet another
problem. Because, regardless of the number of threads that I have in
each place (X10_NTHERADS), the first async task (with the parallel
function) ends first than the async task with the kill variable
update. Then, the algorithm always waits for the end in all places.
I guess that is how the x10 activities scheduler works, unfortunately
with this behavior I don't have any speedup with the parallelism.
You should probably call Runtime.probe() in between the computing calls,
thus. This will give the runtime an opportunity to run and handle
incoming asyncs, such as the one that will set killed to true.
Note that in general one must be careful when calling Runtime.probe().
At this time any incoming activity may be scheduled. If you have written
your code already in such a way that your data structures are safe even
if there are other concurrent activities then you should not have a
problem.
class C {
var killed:Boolean=false;
static def compute() {
val roots= PlaceLocalHandle.make[C](Dist.makeUnique(), ()=> new C());
finish for (p in Place.places()) at(p)async{
sol = roots().parallel_function();
val home =here;
for (p in Place.places() if (home.id <http://home.id> != p.id
<http://p.id>) at(p) async root().killed=true;
}
}
def parallel_function() {
while (! killed) {
continueComputing();
Runtime.probe();
}
// store the result of computing in state on C, now retrieve it
return result();
}
}
An example of code using Runtime.probe is in the UTS application in the
benchmarks directory:
http://x10.svn.sourceforge.net/viewvc/x10/benchmarks/trunk/PERCS/UTS/
Best,
Vijay
Is there a way for this part of the code creates a priority async task?
for (p in Place.places() if (home.id <http://home.id/> != p.id
<http://p.id/>) at(p) async root().killed=true;
Regards,
Danny Múnera
On Tue, Apr 2, 2013 at 1:04 PM, Vijay Saraswat <vi...@saraswat.org
<mailto:vi...@saraswat.org>> wrote:
On 4/2/13 5:06 AM, Danny Munera wrote:
Hello all,
I'm trying to implement an algorithm in parallel. The idea is
using each place as an algorithm independent instance, then,
finishing the program when the first place reaches the solution.
So far, I have something like this:
finish for (p in Place.places()) at(p)async{
sol = parallel_function();
//kill other places
}
Currently, I don't have any idea about how to kill the other
place, I have searched in x10 tutorials, language specification
and the API, and I have not found anything.
Do you have any idea to how to do that?
You don't "kill" a place, you kill the activities running at a
place. Have them periodically check for a variable being set. e.g.
class C {
var killed:Boolean=false;
static def compute() {
val roots= PlaceLocalHandle.make[C](Dist.makeUnique(), ()=>
new C());
finish for (p in Place.places()) at(p)async{
sol = roots().parallel_function();
val home =here;
for (p in Place.places() if (home.id <http://home.id> != p.id
<http://p.id>) at(p) async root().killed=true;
}
}
def parallel_function() {
while (! killed) continueComputing();
// store the result of computing in state on C, now retrieve it
return result();
}
}
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