From ba032bb28bfff3b8d330b026cbd01e6e44be7578 Mon Sep 17 00:00:00 2001
From: jhendersonHDF <jhenderson@hdfgroup.org>
Date: Thu, 3 Mar 2022 09:46:18 -0600
Subject: Disable memory alloc sanity checks by default for Autotools debug
 builds (#1468)

---
 configure.ac             | 17 +++++++++--------
 release_docs/RELEASE.txt | 19 +++++++++++++++++++
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/configure.ac b/configure.ac
index 0ad2228..e426632 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2710,9 +2710,11 @@ AC_ARG_ENABLE([memory-alloc-sanity-check],
                               [Enable this option to turn on internal memory
                               allocation sanity checking.  This could cause
                               more memory use and somewhat slower allocation.
-                              This option is orthogonal to the
-                              --enable-using-memchecker option.
-                               [default=yes if debug build, otherwise no]
+                              This option may also cause issues with HDF5
+                              filter plugins, so should not be enabled if
+                              filters are to be used.  This option is orthogonal
+                              to the --enable-using-memchecker option.
+                               [default=no]
                               ])],
               [MEMORYALLOCSANITYCHECK=$enableval])
 
@@ -2722,11 +2724,10 @@ AC_SUBST([MEMORYALLOCSANITYCHECK])
 
 ## Set default
 if test "X-$MEMORYALLOCSANITYCHECK" = X- ; then
-  if test "X-$BUILD_MODE" = "X-debug" ; then
-    MEMORYALLOCSANITYCHECK=yes
-  else
-    MEMORYALLOCSANITYCHECK=no
-  fi
+# Should consider enabling this option by default for
+# 'developer' builds if that build mode is added in
+# the future
+  MEMORYALLOCSANITYCHECK=no
 fi
 
 case "X-$MEMORYALLOCSANITYCHECK" in
diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index 160675f..8804d52 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -47,6 +47,25 @@ New Features
 
     Configuration:
     -------------
+    - HDF5 memory allocation sanity checking is now off by default for
+      Autotools debug builds
+
+      HDF5 can be configured to perform sanity checking on internal memory
+      allocations by adding heap canaries to these allocations. However,
+      enabling this option can cause issues with external filter plugins
+      when working with (reallocating/freeing/allocating and passing back)
+      buffers.
+
+      Previously, this option was off by default for all CMake build types,
+      but only off by default for non-debug Autotools builds. Since debug
+      is the default build mode for HDF5 when built from source with
+      Autotools, this can result in surprising segfaults that don't occur
+      when an application is built against a release version of HDF5.
+      Therefore, this option is now off by default for all build types
+      across both CMake and Autotools.
+
+      (JTH - 2022/03/01)
+
     - CPack will now generate RPM/DEB packages.
 
       Enabled the RPM and DEB CPack generators on linux. In addition to
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