Hi, Dave,
You're accessing a field (or calling a method) of a remote object
reference. If you ran the compiler with the -STATIC_CALLS flag,
you would have gotten a compile-time error. As it is, the
compiler inserts a dynamic check for you, which then fails at
runtime.
Try compiling your program with -STATIC_CALLS, and see what the
compiler reports.
Hope this helps,
Igor
P.S. Judging by your stack trace, you seem to be running on a Mac.
There was a bug with printing Mac stack traces in X10 2.0.5 which
is fixed in SVN HEAD (so it will work better in the next release).
Dave Hudak <dhu...@osc.edu> wrote on 07/29/2010 12:53:18 PM:
> Hi All,
>
> I took Igor's advice on using a cell to pass results back to the
> calling place. I recoded my function for translating a distarray into
> a string as follows. The "boo/hoo" statements are line counters:
>
> public def place_str(): String
> {
> Console.OUT.println("hoo");
> var s : String = ""; //var is mutable
> Console.OUT.println("hoo1");
> var first : Boolean = true; //var
> declaration must include type
> Console.OUT.println("place_str "+here.id);
> for (pt in a_prefix_sum | here) {
> if (first) {
> first = false;
> }
> else {
> s += ", ";
> }
> Console.OUT.println("place_str point = "+pt);
> s += a_prefix_sum(pt).toString(); //works because
> toString is global
> }
> return s;
> }
>
> public def str():String
> {
> var s : String = ""; //var is mutable
> for (p in a_prefix_sum.dist.places()) {
> Console.OUT.println("str "+p.id);
> val z = new Cell[String](null);
> Console.OUT.println("boo");
> val h = here;
> Console.OUT.println("boo2");
> at (p) {
> Console.OUT.println("boo3");
> val q = place_str();
> Console.OUT.println("boo4");
> at (h) z.set(q);
> Console.OUT.println("boo5");
> }
> s += z();
> if (p.id != (Place.MAX_PLACES - 1)) {
> s += ", ";
> } //if
> Console.OUT.println("s = "+s);
> } //for i
> return s;
> }
>
> I am causing an exception when I call the place_str method from any
> place other that place 0. Here is the output:
>
> dhu...@oscnet166 77%> mpirun -np 8 Driver
> <...snip>
> str 0
> boo
> boo2
> boo3
> hoo
> hoo1
> place_str 0
> place_str point = (1)
> place_str point = (2)
> place_str point = (3)
> place_str point = (4)
> boo4
> boo5
> s = 1, 2, 3, 4,
> str 1
> boo
> boo2
> boo3
> Uncaught exception at place 0: x10.lang.ClassCastException (home==1):
> DistPrefixSum{self.home==here}
> x10.lang.ClassCastException (home==1): DistPrefixSum{self.home==here}
> at x10::lang::Throwable::fillInStackTrace()
>
> Any ideas?
>
> Thanks,
> Dave
> On Jul 28, 2010, at 8:05 PM, Igor Peshansky wrote:
>
> > Igor Peshansky/Watson/i...@ibmus wrote on 07/28/2010 07:15:02 PM:
> >
> >> Dave Hudak <dhu...@osc.edu> wrote on 07/28/2010 02:37:22 PM:
> >>
> >>> Hi All,
> >>>
> >>> I am trying to write a class that will do a prefix sum on an array.
I
> >>> have written the single-place version and a single-place version
that
> >>> uses multiple activities to compute the sums. I am now trying to
> >>> write the distributed version. Both classes are included (I will
> >>> eventually write an interface for these classes).
> >>>
> >>> I have been able to write the constructors and call them without
run-
> >>> time exceptions occurring. Now, I want to write a function that
> >>> returns a single string representation of a dist array. I wrote a
> >>> function that should create a string representation of all dist
array
> >>> elements at a given location (I called it place_str), and then I
want
> >>> to loop over all places:
> >>>
> >>> (from DistPrefixSum.x10):
> >>>
> >>> public def str():String
> >>> {
> >>> var s : String = ""; //var is mutable
> >>> for (var place_id:int=0; place_id<Place.MAX_PLACES; place_id++)
> > {
> >>> s += at (Place.places(place_id)) place_str();
> >>> if (place_id != (Place.MAX_PLACES - 1)) {
> >>> s += ", ";
> >>> } //if
> >>> } //for i
> >>> return s;
> >>> }
> >>>
> >>> My error occurs on the at statement:
> >>>
> >>> dhu...@oscnet166 35%> x10c++ -O -o Driver Driver.x10 PrefixSum.x10
> >>> AsyncPrefixSum.x10 DistPrefixSum.x10
> >>>
> >>
> >
>
/Users/dhudak/osc/research/x10/tutorial/examples/GoodPrefixSum/src/DistPrefixSum.
> >>> x10:49: Local variable "place_id" is accessed from an inner class or
a
> >>> closure, and must be declared final or shared.
> >>> 1 error.
> >>>
> >>> Does anyone have any recommendations? Creating a single string from
a
> >>> dist array of integers is a reduction just like finding the sum or
max
> >>> of the entries, so I figure its well understood...
> >>
> >> Dave,
> >>
> >> This is a bug in the typechecking of at expressions. You can work
> > around
> >> this by changing the body of the for loop to
> >>
> >> val z = new Cell[String](null);
> >> val h = here;
> >> at (Place.places(place_id)) { val q = place_str(); at (h)
> > z.set(q);
> >> }
> >> s += z();
> >> if (place_id != (Place.MAX_PLACES - 1)) {
> >> s += ", ";
> >> } //if
> >>
> >> The above code is less efficient, but it should work.
> >> I've opened a JIRA issue:
http://jira.codehaus.org/browse/XTENLANG-1632
> > .
> >> Please watch that issue for updates on the fix.
> >> Igor
> >
> > Dave,
> >
> > The fix turned out to be simple. This is now fixed in SVN HEAD
(r15224),
> > and will be available in the next X10 release (or you can build from
SVN
> > to pick up the fix).
> > Igor
--
Igor Peshansky (note the spelling change!)
IBM T.J. Watson Research Center
X10: Parallel Productivity and Performance (http://x10-lang.org/)
XJ: No More Pain for XML's Gain (http://www.research.ibm.com/xj/)
"I hear and I forget. I see and I remember. I do and I understand" --
Confucius
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