Universally update to jemalloc 4.0.0.

Summary: Universally update to jemalloc 4.0.0.

Update MALLOC_CONF/malloc_conf configuration, and use the
"arena.<i>.purge" mallctl (replaces "arenas.purge").

Reviewed By: @​bmaurer

Differential Revision: D2355602

folly/Malloc.cpp

@@ -31,7 +31,8 @@ bool usingJEMallocSlow() {
   // (!!). http://goo.gl/xpmctm
   if (mallocx == nullptr || rallocx == nullptr || xallocx == nullptr
       || sallocx == nullptr || dallocx == nullptr || nallocx == nullptr
-      || mallctl == nullptr) {
+      || mallctl == nullptr || mallctlnametomib == nullptr
+      || mallctlbymib == nullptr) {
     return false;
   }
 

folly/Malloc.h

@@ -58,7 +58,7 @@ namespace folly {
 #pragma GCC system_header
 
 /**
- * Declare *allocx() and mallctl() as weak symbols. These will be provided by
+ * Declare *allocx() and mallctl*() as weak symbols. These will be provided by
  * jemalloc if we are using jemalloc, or will be NULL if we are using another
  * malloc implementation.
  */
@@ -76,6 +76,11 @@ extern "C" size_t nallocx(size_t, int)
 __attribute__((__weak__));
 extern "C" int mallctl(const char*, void*, size_t*, void*, size_t)
 __attribute__((__weak__));
+extern "C" int mallctlnametomib(const char*, size_t*, size_t*)
+__attribute__((__weak__));
+extern "C" int mallctlbymib(const size_t*, size_t, void*, size_t*, void*,
+                            size_t)
+__attribute__((__weak__));
 
 #include <bits/functexcept.h>
 #define FOLLY_HAVE_MALLOC_H 1

folly/detail/Malloc.h

@@ -32,6 +32,9 @@ void dallocx(void*, int) __attribute__((__weak__));
 size_t nallocx(size_t, int) __attribute__((__weak__));
 int mallctl(const char*, void*, size_t*, void*, size_t)
       __attribute__((__weak__));
+int mallctlnametomib(const char*, size_t*, size_t*) __attribute__((__weak__));
+int mallctlbymib(const size_t*, size_t, void*, size_t*, void*, size_t)
+      __attribute__((__weak__));
 #else
 extern void* (*mallocx)(size_t, int);
 extern void* (*rallocx)(void*, size_t, int);
@@ -40,6 +43,9 @@ extern size_t (*sallocx)(const void*, int);
 extern void (*dallocx)(void*, int);
 extern size_t (*nallocx)(size_t, int);
 extern int (*mallctl)(const char*, void*, size_t*, void*, size_t);
+extern int (*mallctlnametomib)(const char*, size_t*, size_t*);
+extern int (*mallctlbymib)(const size_t*, size_t, void*, size_t*, void*,
+                           size_t);
 #endif
 
 }

folly/detail/MallocImpl.cpp

@@ -26,6 +26,9 @@ size_t (*sallocx)(const void*, int) = nullptr;
 void (*dallocx)(void*, int) = nullptr;
 size_t (*nallocx)(size_t, int) = nullptr;
 int (*mallctl)(const char*, void*, size_t*, void*, size_t) = nullptr;
+int (*mallctlnametomib)(const char*, size_t*, size_t*) = nullptr;
+int (*mallctlbymib)(const size_t*, size_t, void*, size_t*, void*, size_t) =
+    nullptr;
 #endif
 
 }

folly/detail/MemoryIdler.cpp

@@ -51,8 +51,8 @@ static unsigned mallctlWrapper(const char* cmd, const unsigned* in,
 
 void MemoryIdler::flushLocalMallocCaches() {
   if (usingJEMalloc()) {
-    if (!mallctl) {
-      FB_LOG_EVERY_MS(ERROR, 10000) << "mallctl weak link failed";
+    if (!mallctl || !mallctlnametomib || !mallctlbymib) {
+      FB_LOG_EVERY_MS(ERROR, 10000) << "mallctl* weak link failed";
       return;
     }
 
@@ -69,12 +69,15 @@ void MemoryIdler::flushLocalMallocCaches() {
     // purging the arenas is counter-productive.  We use the heuristic
     // that if narenas <= 2 * num_cpus then we shouldn't do anything here,
     // which detects when the narenas has been reduced from the default
-    unsigned narenas;
-    unsigned arenaForCurrent;
-    if (mallctlWrapper("arenas.narenas", nullptr, &narenas) == 0 &&
+    unsigned narenas, arenaForCurrent;
+    size_t mib[3];
+    size_t miblen = 3;
+    if (mallctlWrapper("opt.narenas", nullptr, &narenas) == 0 &&
         narenas > 2 * CacheLocality::system().numCpus &&
-        mallctlWrapper("thread.arena", nullptr, &arenaForCurrent) == 0) {
-      (void)mallctlWrapper("arenas.purge", &arenaForCurrent, nullptr);
+        mallctlWrapper("thread.arena", nullptr, &arenaForCurrent) == 0 &&
+        mallctlnametomib("arena.0.purge", mib, &miblen) == 0) {
+      mib[1] = size_t(arenaForCurrent);
+      mallctlbymib(mib, miblen, nullptr, nullptr, nullptr, 0);
     }
   }
 }

folly/test/small_vector_test.cpp

@@ -269,7 +269,7 @@ TEST(small_vector, BasicGuarantee) {
 
 // Run this with.
 // MALLOC_CONF=prof_leak:true
-// LD_PRELOAD=${JEMALLOC_PATH}/lib/libjemalloc.so.1
+// LD_PRELOAD=${JEMALLOC_PATH}/lib/libjemalloc.so.2
 // LD_PRELOAD="$LD_PRELOAD:"${UNWIND_PATH}/lib/libunwind.so.7
 TEST(small_vector, leak_test) {
   for (int j = 0; j < 1000; ++j) {