ARROW-6977: [C++] Disable jemalloc background_thread on macOS

The option isn't always available, perhaps based on the macOS version
or configured SDK version.

Closes #5729 from pitrou/ARROW-6977-macos-jemalloc-background-thread and squashes the following commits:

42ff1a9 <Antoine Pitrou> ARROW-6977:  Disable jemalloc background_thread on macOS

Authored-by: Antoine Pitrou <antoine@python.org>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>

.github/workflows/windows-msvc-cpp.yml

@@ -36,6 +36,7 @@ jobs:
     steps:
       - uses: actions/checkout@master
       - name: CMake
+        shell: cmd
         run: |
           mkdir build\cpp
           cmake ^
@@ -48,5 +49,6 @@ jobs:
             -S cpp ^
             -B build\cpp
       - name: Install
+        shell: cmd
         run: |
           cmake --build build\cpp --config Debug --target Install

cpp/src/arrow/memory_pool.cc

@@ -53,22 +53,29 @@
 // aggressively (and in the background) to the OS. This can be configured
 // further by using the arrow::jemalloc_set_decay_ms API
 
+#undef USE_JEMALLOC_BACKGROUND_THREAD
+#ifndef __APPLE__
+// ARROW-6977: jemalloc's background_thread isn't always enabled on macOS
+#define USE_JEMALLOC_BACKGROUND_THREAD
+#endif
+
+// In debug mode, add memory poisoning on alloc / free
 #ifdef NDEBUG
-const char* je_arrow_malloc_conf =
-    ("oversize_threshold:0,"
-     "dirty_decay_ms:1000,"
-     "muzzy_decay_ms:1000,"
-     "background_thread:true");
+#define JEMALLOC_DEBUG_OPTIONS ""
 #else
-// In debug mode, add memory poisoning on alloc / free
-const char* je_arrow_malloc_conf =
-    ("oversize_threshold:0,"
-     "junk:true,"
-     "dirty_decay_ms:1000,"
-     "muzzy_decay_ms:1000,"
-     "background_thread:true");
+#define JEMALLOC_DEBUG_OPTIONS ",junk:true"
 #endif
+
+const char* je_arrow_malloc_conf =
+    ("oversize_threshold:0"
+     ",dirty_decay_ms:1000"
+     ",muzzy_decay_ms:1000"
+#ifdef USE_JEMALLOC_BACKGROUND_THREAD
+     ",background_thread:true"
 #endif
+     JEMALLOC_DEBUG_OPTIONS);  // NOLINT: whitespace/parens
+
+#endif  // ARROW_JEMALLOC
 
 namespace arrow {