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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - omp cancel parallel not working as expected"
href="https://bugs.llvm.org/show_bug.cgi?id=50129">50129</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>omp cancel parallel not working as expected
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>All
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>OpenMP
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>michael.p.rice@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>The following test shows 'omp cancel' is not working as expected. Run with:
OMP_CANCELLATION=true ./a.out
It should quickly print:
Cancel happened as you would expect!
Clang will not cancel.
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <unistd.h>
// Run with environment variable: OMP_CANCELLATION=true
int main(int argc, char **argv) {
int* array;
int nthreads, i, j;
#pragma omp parallel
#pragma omp single nowait
nthreads = omp_get_num_threads();
array = (int*)malloc(sizeof(int)*nthreads);
for (i = 0; i < nthreads; ++i)
array[i] = 0;
assert(omp_get_cancellation() && "Need to set OMP_CANCELLATION=true");
#pragma omp parallel
{
int tid = omp_get_thread_num();
if (tid == 0) {
// Master signals other threads that cancellation is in order
// This thread will go to end of parallel right here
// not at the cancellation point below
#pragma omp cancel parallel
}
// Have worker threads sleep here for "long enough"
usleep(1000000);
#pragma omp barrier
array[tid] = 1;
}
int errors = 0;
for (i = 0; i < nthreads; ++i) {
if (array[i] != 0) {
printf("Thread %d made it through unexpectedly!\n", i);
errors++;
}
}
if (errors) {
printf("%d errors occurred!\n", errors);
exit(1);
}
printf("Cancel happened as you would expect!\n");
return 0;
}</pre>
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