From 57e5c4305cb0b741fb28fc7286ae9dd11d4acf56 Mon Sep 17 00:00:00 2001
From: David Young <dyoung@hdfgroup.org>
Date: Thu, 30 Apr 2020 15:22:36 -0500
Subject: Avoid deadlock of reader and writer: make the writer flush file
 content before waiting for the reader's message.

---
 test/vfd_swmr_common.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/test/vfd_swmr_common.c b/test/vfd_swmr_common.c
index bf1cc59..7db2bba 100644
--- a/test/vfd_swmr_common.c
+++ b/test/vfd_swmr_common.c
@@ -122,6 +122,12 @@ await_signal(hid_t fid)
             __func__, __LINE__);
     }
 
+    /* Avoid deadlock: flush the file before waiting for the reader's
+     * message.
+     */
+    if (H5Fflush(fid, H5F_SCOPE_GLOBAL) < 0)
+        errx(EXIT_FAILURE, "%s: H5Fflush failed", __func__);
+
     for (;;) {
         const int rc = sigtimedwait(&sleepset, NULL, &tick);
 
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