[Ipopt-tickets] [Ipopt] #245: Crash on Java when calculating gradient using multi-threading

[Ipopt]

#245: Crash on Java when calculating gradient using multi-threading
---------------------------------+------------------------
Reporter:  shouji                |      Owner:  ipopt-team
    Type:  defect                |     Status:  new
Priority:  normal                |  Component:  Ipopt
 Version:  3.3                   |   Severity:  blocker
Keywords:  Java multi-threading  |
---------------------------------+------------------------
 I use IPOPT by the Java interface (3.3.2). I understand that the IPOPT
 itself is not thread-safe, so I tried to calculate the gradient of the
 target function by multi-threading as a work-around. Part of my IPOPT code
 in Java is listed below.

 For input with large number of variables ( n is about 7300), it seems to
 run smoothly. However, for small input with small n (about 50), it
 frequently crashed at different points. I would like to know if there is a
 way to fix that. Thanks.




 @Override
         protected boolean eval_grad_f(int n, double[] x, boolean new_x,
                         double[] grad_f) {
                 try {
                         assert n == this.n;
                         ExecutorService executor = Executors
                                         .newFixedThreadPool(numberOfCpu);

                         Collection<Future<?>> futures = new
 LinkedList<Future<?>>();
                         for (int i = 0; i <= n - 1; i++) {
                                 futures.add(executor.submit(new
 GradientCalculationTaskNew(
                                                 namfisOptimizerInputData,
 grad_f, i)));
                         }
                         executor.shutdown();

                         for (Future<?> future : futures) {
                                 future.get();
                         }

                         return true;

                 } catch (InterruptedException e) {
                         e.printStackTrace();
                         return false;
                 } catch (ExecutionException e) {
                         e.printStackTrace();
                         return false;
                 }
         }

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Ticket URL: <https://projects.coin-or.org/Ipopt/ticket/245>
Ipopt <http://projects.coin-or.org/Ipopt>
Interior-point optimizer for nonlinear programs.