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10267 :: FMU library - fmi2FreeInstance

• mantielero (orginal) [2023-06-12T20:36:12+02:00] view original

  Now the simulation runs fine, but it is not finishing nicely.

  In the C, there are many commands freeing the memory:

  void fmi2FreeInstance(fmi2Component c) {
      ModelInstance *comp = (ModelInstance *)c;
      if (!comp) return;
      if (invalidState(comp, "fmi2FreeInstance", MASK_fmi2FreeInstance))
          return;
      FILTERED_LOG(comp, fmi2OK, LOG_FMI_CALL, "fmi2FreeInstance")
      
      if (comp->r) comp->functions->freeMemory(comp->r);
      if (comp->i) comp->functions->freeMemory(comp->i);
      if (comp->b) comp->functions->freeMemory(comp->b);
      if (comp->s) {
          int i;
          for (i = 0; i < NUMBER_OF_STRINGS; i++){
              if (comp->s[i]) comp->functions->freeMemory((void *)comp->s[i]);
          }
          comp->functions->freeMemory((void *)comp->s);
      }
      if (comp->isPositive) comp->functions->freeMemory(comp->isPositive);
      if (comp->instanceName) comp->functions->freeMemory((void *)comp->instanceName);
      if (comp->GUID) comp->functions->freeMemory((void *)comp->GUID);
      comp->functions->freeMemory(comp);
  }
  Run

  Given that I keep ModelInstance as a Nim object and I am passing ModelInstanceRef (a ref object) across all functions fmi2xxx functions, how should I clean the memory properly?

  I tried the following:

  1. Assigning nil:

  proc fmi2FreeInstance(comp: ModelInstanceRef) =
      echo "ENTERING: fmi2FreeInstance"
      comp = nil
  Run

  but it fails to compile:Error: 'comp' cannot be assigned to.

  2. If I do:

  proc fmi2FreeInstance(comp: var ModelInstanceRef) =
      echo "ENTERING: fmi2FreeInstance"
      comp = nil
  Run

  it compiles and runs fine, but it finish with a seg fault:

  
  [INFO][FMUCHK] Simulation finished successfully at time 1
  ENTERING: fmi2FreeInstance
  munmap_chunk(): invalid pointer
  ./build.sh: line 8: 694837 Segmentation fault      (core dumped) ./fmuCheck.linux64 inc.fmu
  Run

  How should I remove the reference to the object?

  Should I also implement =destroy for the ModelInstance object?

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• mantielero (orginal) [2023-06-13T08:56:58+02:00] view original

  Well, I fixed it with:

  proc fmi2FreeInstance*(comp: ModelInstanceRef) =
      `=destroy`(comp[])
      GC_fullCollect()
  Run

  I hope this helps others.

  Valgrind says:

  
  ==716751==
  ==716751== HEAP SUMMARY:
  ==716751==     in use at exit: 0 bytes in 0 blocks
  ==716751==   total heap usage: 243 allocs, 243 frees, 459,502 bytes allocated
  ==716751==
  ==716751== All heap blocks were freed -- no leaks are possible
  ==716751==
  ==716751== For lists of detected and suppressed errors, rerun with: -s
  ==716751== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
  Run

  So this looks good.

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