[gcc r16-8938] libstdc++: Reduce iterations in PSTL test for Debug Mode

[Jonathan Wakely]

https://gcc.gnu.org/g:40e11138dbfbf1a155372f737bf41358b3cb7d70

commit r16-8938-g40e11138dbfbf1a155372f737bf41358b3cb7d70
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Sun May 17 19:27:11 2026 +0100

    libstdc++: Reduce iterations in PSTL test for Debug Mode
    
    This test often times out, especially on machines with a large number of
    cores when the tests are run with a lot of parallel jobs. I suspect that
    TBB creates a lot of threads due to std::hardware_concurrency() being a
    large number, but because most cores are already busy running other
    tests (due to `make -jN check` with large N) the system gets
    oversubscribed. In Debug Mode, the testcase runs much slower, and often
    times out.
    
    It's probably fine to just test with fewer iterations when Debug Mode is
    active.
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/25_algorithms/pstl/alg_sorting/minmax_element.cc:
            Reduce iterations for debug mode.
    
    (cherry picked from commit 6df1f865272fc95f386f5448f3a74486451bb58c)

Diff:
---
 .../testsuite/25_algorithms/pstl/alg_sorting/minmax_element.cc        | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libstdc++-v3/testsuite/25_algorithms/pstl/alg_sorting/minmax_element.cc b/libstdc++-v3/testsuite/25_algorithms/pstl/alg_sorting/minmax_element.cc
index e4bd435d1926..51bdeaa96a13 100644
--- a/libstdc++-v3/testsuite/25_algorithms/pstl/alg_sorting/minmax_element.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/pstl/alg_sorting/minmax_element.cc
@@ -189,7 +189,11 @@ int
 main()
 {
     using TestUtils::float64_t;
+#ifndef _GLIBCXX_DEBUG
     const std::size_t N = 100000;
+#else
+    const std::size_t N = 10000;
+#endif
 
     for (std::size_t n = 0; n < N; n = n < 16 ? n + 1 : size_t(3.14159 * n))
     {