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authorDavid Young <dyoung@hdfgroup.org>2020-02-27 22:14:44 (GMT)
committerDavid Young <dyoung@hdfgroup.org>2020-02-27 22:14:44 (GMT)
commit803d805c74466a9d736455930b17de2d9f5cb02d (patch)
tree3fccf966bbe9b5f8fb46ac8107e0a77bb7c22e5f
parent4be589813a8fc5e2c5313464b088d7d3c31a754d (diff)
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Complete the comment on thread_main(), explaining why the barrier is used.
-rw-r--r--test/thread_id.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/test/thread_id.c b/test/thread_id.c
index e3cf42e..818ab4a 100644
--- a/test/thread_id.c
+++ b/test/thread_id.c
@@ -226,7 +226,15 @@ atomic_printf(const char *fmt, ...)
/* Each thread runs this routine. The routine fetches the current
* thread's ID, makes sure that it is in the expected range, makes
* sure that in this round of testing, no two threads shared the
- * same ID,
+ * same ID, and checks that each thread's ID is constant over its lifetime.
+ *
+ * main() checks that every ID in [1, NTHREADS] is used in each round
+ * of testing. All NTHREADS threads synchronize on a barrier after each
+ * has fetched its ID. The barrier guarantees that all threads' lifetimes
+ * overlap at least momentarily, so the IDs will be unique, and there
+ * will be NTHREADS of them. Further, since thread IDs are assigned
+ * starting with 1, and the number of threads with IDs alive never exceeds
+ * NTHREADS, the least ID has to be 1 and the greatest, NTHREADS.
*/
static void *
thread_main(void H5_ATTR_UNUSED *arg)