fix wraparound race conditionMDEV-24676_cpp

also improve locking granularity regarding flush
remove atomic on bool, since it is already protected under lock
add more volatile specs
add comments, improve structure packing

1 files changed, 3 insertions, 1 deletions

diff --git a/io_cache_test/io_cache_test.cpp b/io_cache_test/io_cache_test.cpp
index 947baa6cc47..5bb8dd0f1db 100644
--- a/io_cache_test/io_cache_test.cpp
+++ b/io_cache_test/io_cache_test.cpp
@@ -18,6 +18,8 @@ void *read_to_cache(void *) {
 }
 
 void *write_to_cache(void *args) {
+  struct st_my_thread_var thdvar;
+  set_mysys_var(&thdvar);
   pthread_barrier_wait(&barrier);
   int *v_args= (int *) args;
   for (int i= v_args[0]; i < v_args[1]; ++i)
@@ -90,4 +92,4 @@ int main() {
   of.open("test_out.txt", std::ios_base::out);
   of << buff_to;
   return 0;
-}
\ No newline at end of file
+}