From 625488ace5c41ccba1b68323a72588000782f820 Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Thu, 30 Mar 2017 09:37:47 +0200
Subject: [PATCH] util: Work around (virtual) memory exhaustion on 32-bit w/
 glibc

glibc-specific: On 32-bit systems set the number of arenas to 1. By
default, since glibc 2.10, the C library will create up to two heap
arenas per core. This is known to cause excessive virtual address space
usage in our usage. Work around it by setting the maximum number of
arenas to 1.
---
 configure.ac |  8 ++++++++
 src/util.cpp | 14 ++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/configure.ac b/configure.ac
index 2a9ee018a..8aa9387dc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -574,6 +574,14 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <malloc.h>]],
  [ AC_MSG_RESULT(no)]
 )
 
+dnl Check for mallopt(M_ARENA_MAX) (to set glibc arenas)
+AC_MSG_CHECKING(for mallopt M_ARENA_MAX)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <malloc.h>]],
+ [[ mallopt(M_ARENA_MAX, 1); ]])],
+ [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_MALLOPT_ARENA_MAX, 1,[Define this symbol if you have mallopt with M_ARENA_MAX]) ],
+ [ AC_MSG_RESULT(no)]
+)
+
 AC_MSG_CHECKING([for visibility attribute])
 AC_LINK_IFELSE([AC_LANG_SOURCE([
   int foo_def( void ) __attribute__((visibility("default")));
diff --git a/src/util.cpp b/src/util.cpp
index 486df772f..a997199fb 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -72,6 +72,10 @@
 #include <sys/prctl.h>
 #endif
 
+#ifdef HAVE_MALLOPT_ARENA_MAX
+#include <malloc.h>
+#endif
+
 #include <boost/algorithm/string/case_conv.hpp> // for to_lower()
 #include <boost/algorithm/string/join.hpp>
 #include <boost/algorithm/string/predicate.hpp> // for startswith() and endswith()
@@ -792,6 +796,16 @@ void RenameThread(const char* name)
 
 void SetupEnvironment()
 {
+#ifdef HAVE_MALLOPT_ARENA_MAX
+    // glibc-specific: On 32-bit systems set the number of arenas to 1.
+    // By default, since glibc 2.10, the C library will create up to two heap
+    // arenas per core. This is known to cause excessive virtual address space
+    // usage in our usage. Work around it by setting the maximum number of
+    // arenas to 1.
+    if (sizeof(void*) == 4) {
+        mallopt(M_ARENA_MAX, 1);
+    }
+#endif
     // On most POSIX systems (e.g. Linux, but not BSD) the environment's locale
     // may be invalid, in which case the "C" locale is used as fallback.
 #if !defined(WIN32) && !defined(MAC_OSX) && !defined(__FreeBSD__) && !defined(__OpenBSD__)