Hi
I have a loop like so:
<Original>
int index = 0;
for(int step = 0; iteration_time <= 0.5*time; ++step) {
iteration_time += some_step;
for (std::vector<some_object> p = test.begin(); p != test.end();
++p) {
do some stuff
old_solution_u(index) = do_some_calculation();
++index;
}
}
</Original>
'old_solution_u' is a vector of solution values. The loop writes values into
it in exactly the same order as the support points.
I'd like to use multithreading, so I converted it, following 'step 9' like
so:
template <int dim>
void TestEquation<dim>::iterate()
{
const unsigned int n_threads = multithread_info.n_default_threads;
Threads::ThreadGroup<> threads;
std::vector<std::pair<TestIterator, TestIterator> >
thread_ranges = Threads::split_range<TestIterator>( test.begin(),
test.end(),
n_threads );
for ( unsigned int thread = 0; thread < n_threads; ++thread )
threads += Threads::new_thread
(&TestEquation<dim>::test_iteration_interval,
*this,
time,
thread_ranges[thread].first,
thread_ranges[thread].second);
threads.join_all();
}
template <int dim>
void TestEquation<dim>::test_iteration_interval(double time, TestIterator
&begin, TestIterator &end) {
TestIterator p;
for(int step = 0, index = 0; iteration_time <= 0.5*time; ++step,
++index) {
iteration_time += some_step;
for (p = begin; p != end; ++p) {
do some stuff
write_lock.acquire();
old_solution_u(index) = do_some_calculation();
write_lock.release();
}
}
}
The multithreading works brilliantly but the results are incorrect. Are
there errors in how I've done it above?
--
Many thanks,
Ted
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