feat(server): high level active defrag dragonflydb#448

Signed-off-by: Boaz Sade <boaz@dragonflydb.io>

src/core/compact_object.cc

@@ -39,6 +39,7 @@ using absl::GetFlag;
 namespace {
 
 constexpr XXH64_hash_t kHashSeed = 24061983;
+constexpr size_t kAlignSize = 8u;
 
 // Approximation since does not account for listpacks.
 size_t QlMAllocSize(quicklist* ql) {
@@ -217,7 +218,7 @@ struct TL {
 
 thread_local TL tl;
 
-constexpr bool kUseSmallStrings = true;
+constexpr bool kUseSmallStrings = false;
 
 /// TODO: Ascii encoding becomes slow for large blobs. We should factor it out into a separate
 /// file and implement with SIMD instructions.
@@ -398,13 +399,13 @@ void RobjWrapper::MakeInnerRoom(size_t current_cap, size_t desired, pmr::memory_
       desired += SDS_MAX_PREALLOC;
   }
 
-  void* newp = mr->allocate(desired, 8);
+  void* newp = mr->allocate(desired, kAlignSize);
   if (sz_) {
     memcpy(newp, inner_obj_, sz_);
   }
 
   if (current_cap) {
-    mr->deallocate(inner_obj_, current_cap, 8);
+    mr->deallocate(inner_obj_, current_cap, kAlignSize);
   }
   inner_obj_ = newp;
 }
@@ -659,7 +660,7 @@ robj* CompactObj::AsRObj() const {
   res->type = u_.r_obj.type();
 
   if (res->type == OBJ_SET) {
-    LOG(FATAL) << "Should not call AsRObj for type " <<  res->type;
+    LOG(FATAL) << "Should not call AsRObj for type " << res->type;
   }
 
   if (res->type == OBJ_HASH) {

src/core/compact_object.h

@@ -16,7 +16,7 @@ typedef struct redisObject robj;
 namespace dfly {
 
 constexpr unsigned kEncodingIntSet = 0;
-constexpr unsigned kEncodingStrMap = 1;  // for set/map encodings of strings
+constexpr unsigned kEncodingStrMap = 1;   // for set/map encodings of strings
 constexpr unsigned kEncodingStrMap2 = 2;  // for set/map encodings of strings using DenseSet
 constexpr unsigned kEncodingListPack = 3;
 

src/core/compact_object_test.cc

@@ -3,9 +3,9 @@
 //
 #include "core/compact_object.h"
 
+#include <absl/strings/str_cat.h>
 #include <mimalloc.h>
 #include <xxhash.h>
-#include <absl/strings/str_cat.h>
 
 #include "base/gtest.h"
 #include "base/logging.h"
@@ -34,6 +34,36 @@ void PrintTo(const CompactObj& cobj, std::ostream* os) {
   *os << "cobj: [" << cobj.ObjType() << "]";
 }
 
+// This is for the mimalloc test - being able to find an address in memory
+// where we have memory underutilzation
+// see issue number 448 (https://github.com/dragonflydb/dragonfly/issues/448)
+std::vector<void*> AllocateForTest(int size, std::size_t allocate_size, int factor1 = 1,
+                                   int factor2 = 1) {
+  std::vector<void*> ptrs;
+  for (int index = 0; index < size; index++) {
+    auto alloc_size = index % 13 == 0 ? allocate_size * factor1 : allocate_size * factor2;
+    auto heap_alloc = mi_heap_get_backing();
+    void* ptr = mi_heap_malloc(heap_alloc, alloc_size);
+    ptrs.push_back(ptr);
+  }
+  return ptrs;
+}
+
+bool FindUnderutilizedMemory(const std::vector<void*>& ptrs, float ratio) {
+  auto it = std::find_if(ptrs.begin(), ptrs.end(), [&](auto p) {
+    int r = p && zmalloc_page_is_underutilized(p, ratio);
+    return r > 0;
+  });
+  return it != ptrs.end();
+}
+
+void DecimateMemory(std::vector<void*>* ptrs, size_t steps) {
+  for (size_t i = 24; i < ptrs->size(); i += steps) {
+    mi_free(ptrs->at(i));
+    ptrs->at(i) = nullptr;
+  }
+}
+
 class CompactObjectTest : public ::testing::Test {
  protected:
   static void SetUpTestSuite() {
@@ -110,7 +140,6 @@ TEST_F(CompactObjectTest, InlineAsciiEncoded) {
   EXPECT_EQ(s.size(), obj.Size());
 }
 
-
 TEST_F(CompactObjectTest, Int) {
   cobj_.SetString("0");
   EXPECT_EQ(0, cobj_.TryGetInt());
@@ -211,13 +240,13 @@ TEST_F(CompactObjectTest, FlatSet) {
   size_t allocated2, resident2, active2;
 
   zmalloc_get_allocator_info(&allocated1, &active1, &resident1);
-  dict *d = dictCreate(&setDictType);
+  dict* d = dictCreate(&setDictType);
   constexpr size_t kTestSize = 2000;
 
   for (size_t i = 0; i < kTestSize; ++i) {
     sds key = sdsnew("key:000000000000");
     key = sdscatfmt(key, "%U", i);
-    dictEntry *de = dictAddRaw(d, key,NULL);
+    dictEntry* de = dictAddRaw(d, key, NULL);
     de->v.val = NULL;
   }
 
@@ -259,4 +288,66 @@ TEST_F(CompactObjectTest, StreamObj) {
   EXPECT_FALSE(cobj_.IsInline());
 }
 
+TEST_F(CompactObjectTest, MimallocUnderutilzation) {
+  // We are testing with the same object size allocation here
+  // This test is for https://github.com/dragonflydb/dragonfly/issues/448
+  size_t allocation_size = 94;
+  int count = 2000;
+  std::vector<void*> ptrs = AllocateForTest(count, allocation_size);
+  bool found = FindUnderutilizedMemory(ptrs, 1.0f);
+  ASSERT_FALSE(found);
+  DecimateMemory(&ptrs, 26);
+  found = FindUnderutilizedMemory(ptrs, 1.0f);
+  ASSERT_TRUE(found);
+  for (auto* ptr : ptrs) {
+    mi_free(ptr);
+  }
+}
+
+TEST_F(CompactObjectTest, MimallocUnderutilzationDifferentSizes) {
+  // This test uses different objects sizes to cover more use cases
+  // related to issue https://github.com/dragonflydb/dragonfly/issues/448
+  size_t allocation_size = 97;
+  int count = 2000;
+  int mem_factor_1 = 3;
+  int mem_factor_2 = 2;
+  std::vector<void*> ptrs = AllocateForTest(count, allocation_size, mem_factor_1, mem_factor_2);
+  bool found = FindUnderutilizedMemory(ptrs, 1.0f);
+  ASSERT_FALSE(found);
+  DecimateMemory(&ptrs, 26);
+  found = FindUnderutilizedMemory(ptrs, 1.0f);
+  ASSERT_TRUE(found);
+  for (auto* ptr : ptrs) {
+    mi_free(ptr);
+  }
+}
+
+TEST_F(CompactObjectTest, MimallocUnderutilzationWithRealloc) {
+  // This test is checking underutilzation with reallocation as well as deallocation
+  // of the memory - see issue https://github.com/dragonflydb/dragonfly/issues/448
+  size_t allocation_size = 102;
+  int count = 2000;
+  int mem_factor_1 = 4;
+  int mem_factor_2 = 1;
+  std::vector<void*> ptrs = AllocateForTest(count, allocation_size, mem_factor_1, mem_factor_2);
+  bool found = FindUnderutilizedMemory(ptrs, 1.0f);
+  ASSERT_FALSE(found);
+  DecimateMemory(&ptrs, 26);
+  // TestMiMallocUnderutilized(ptrs, run_reallocation, allocation_size);
+  //  This is another case, where we are filling the "gaps" by doing re-allocations
+  //  in this case, since we are not setting all the values back it should still have
+  //  places that are not used. Plus since we are not looking at the first page
+  //  other pages should be underutilized.
+  for (size_t i = 24; i < ptrs.size(); i += 26) {
+    if (!ptrs[i]) {
+      ptrs[i] = mi_heap_malloc(mi_heap_get_backing(), allocation_size);
+    }
+  }
+  found = FindUnderutilizedMemory(ptrs, 1.0f);
+  ASSERT_TRUE(found);
+  for (auto* ptr : ptrs) {
+    mi_free(ptr);
+  }
+}
+
 }  // namespace dfly

src/redis/zmalloc.h

@@ -38,7 +38,9 @@
 #define __zm_str(s) #s
 
 #if defined(USE_JEMALLOC)
-#define ZMALLOC_LIB ("jemalloc-" __xstr(JEMALLOC_VERSION_MAJOR) "." __xstr(JEMALLOC_VERSION_MINOR) "." __xstr(JEMALLOC_VERSION_BUGFIX))
+#define ZMALLOC_LIB                                                                          \
+  ("jemalloc-" __xstr(JEMALLOC_VERSION_MAJOR) "." __xstr(JEMALLOC_VERSION_MINOR) "." __xstr( \
+      JEMALLOC_VERSION_BUGFIX))
 #include <jemalloc/jemalloc.h>
 #if (JEMALLOC_VERSION_MAJOR == 2 && JEMALLOC_VERSION_MINOR >= 1) || (JEMALLOC_VERSION_MAJOR > 2)
 #define HAVE_MALLOC_SIZE 1
@@ -82,35 +84,35 @@
 #define HAVE_DEFRAG
 #endif
 
-void *zmalloc(size_t size);
-void *zcalloc(size_t size);
-void *zrealloc(void *ptr, size_t size);
-void *ztrymalloc(size_t size);
-void *ztrycalloc(size_t size);
-void *ztryrealloc(void *ptr, size_t size);
-void zfree(void *ptr);
+void* zmalloc(size_t size);
+void* zcalloc(size_t size);
+void* zrealloc(void* ptr, size_t size);
+void* ztrymalloc(size_t size);
+void* ztrycalloc(size_t size);
+void* ztryrealloc(void* ptr, size_t size);
+void zfree(void* ptr);
 
-size_t znallocx(size_t size); // Equivalent to nallocx for jemalloc or mi_good_size for mimalloc.
+size_t znallocx(size_t size);  // Equivalent to nallocx for jemalloc or mi_good_size for mimalloc.
 void zfree_size(void* ptr, size_t size);  // equivalent to sdallocx or mi_free_size
 
-void *zmalloc_usable(size_t size, size_t *usable);
-void *zcalloc_usable(size_t size, size_t *usable);
-void *zrealloc_usable(void *ptr, size_t size, size_t *usable);
-void *ztrymalloc_usable(size_t size, size_t *usable);
-void *ztrycalloc_usable(size_t size, size_t *usable);
-void *ztryrealloc_usable(void *ptr, size_t size, size_t *usable);
+void* zmalloc_usable(size_t size, size_t* usable);
+void* zcalloc_usable(size_t size, size_t* usable);
+void* zrealloc_usable(void* ptr, size_t size, size_t* usable);
+void* ztrymalloc_usable(size_t size, size_t* usable);
+void* ztrycalloc_usable(size_t size, size_t* usable);
+void* ztryrealloc_usable(void* ptr, size_t size, size_t* usable);
 
 // size_t zmalloc_used_memory(void);
 void zmalloc_set_oom_handler(void (*oom_handler)(size_t));
 size_t zmalloc_get_rss(void);
-int zmalloc_get_allocator_info(size_t *allocated, size_t *active, size_t *resident);
+int zmalloc_get_allocator_info(size_t* allocated, size_t* active, size_t* resident);
 void set_jemalloc_bg_thread(int enable);
 int jemalloc_purge();
 size_t zmalloc_get_private_dirty(long pid);
-size_t zmalloc_get_smap_bytes_by_field(char *field, long pid);
+size_t zmalloc_get_smap_bytes_by_field(char* field, long pid);
 size_t zmalloc_get_memory_size(void);
 size_t zmalloc_usable_size(const void* p);
-
+int zmalloc_page_is_underutilized(void* ptr, float ratio);
 // roman: void zlibc_free(void *ptr);
 
 void init_zmalloc_threadlocal(void* heap);

src/redis/zmalloc_mi.c

@@ -137,3 +137,7 @@ void init_zmalloc_threadlocal(void* heap) {
     return;
   zmalloc_heap = heap;
 }
+
+int zmalloc_page_is_underutilized(void* ptr, float ratio) {
+  return mi_heap_page_is_underutilized(zmalloc_heap, ptr, ratio);
+}

src/server/CMakeLists.txt

@@ -7,7 +7,7 @@ if (CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64" AND CMAKE_BUILD_TYPE STREQUAL "Rele
   set_source_files_properties(dfly_main.cc PROPERTIES COMPILE_FLAGS -march=core2 COMPILE_DEFINITIONS SOURCE_PATH_FROM_BUILD_ENV=${CMAKE_SOURCE_DIR})
 endif()
 
-add_library(dfly_transaction db_slice.cc engine_shard_set.cc blocking_controller.cc common.cc
+add_library(dfly_transaction db_slice.cc malloc_stats.cc engine_shard_set.cc blocking_controller.cc common.cc
             io_mgr.cc journal/journal.cc journal/journal_slice.cc table.cc
             tiered_storage.cc transaction.cc)
 cxx_link(dfly_transaction uring_fiber_lib dfly_core strings_lib)

src/server/dragonfly_test.cc

@@ -50,6 +50,13 @@ class DflyEngineTest : public BaseFamilyTest {
   }
 };
 
+class DefragDflyEngineTest : public DflyEngineTest {
+ protected:
+  DefragDflyEngineTest() : DflyEngineTest() {
+    num_threads_ = 1;
+  }
+};
+
 // TODO: to implement equivalent parsing in redis parser.
 TEST_F(DflyEngineTest, Sds) {
   int argc;
@@ -749,6 +756,27 @@ TEST_F(DflyEngineTest, Bug496) {
   });
 }
 
+TEST_F(DefragDflyEngineTest, TestDefragOption) {
+  // Fill data into dragonfly and then check if we have
+  // any location in memory to defrag. See issue #448 for details about this.
+  EXPECT_GE(max_memory_limit, 100'000);
+  const int NUMBER_OF_KEYS = 184000;
+
+  RespExpr resp = Run({"DEBUG", "POPULATE", std::to_string(NUMBER_OF_KEYS), "key-name", "130"});
+  ASSERT_EQ(resp, "OK");
+  resp = Run({"DBSIZE"});
+  EXPECT_THAT(resp, IntArg(NUMBER_OF_KEYS));
+
+  shard_set->pool()->AwaitFiberOnAll([&](unsigned index, ProactorBase* base) {
+    EngineShard* shard = EngineShard::tlocal();
+    ASSERT_FALSE(shard == nullptr);  // we only have one and its should not be empty!
+    EXPECT_EQ(shard->GetDefragStats().success_count, 0);
+    // should not run at all!!
+    EXPECT_EQ(shard->GetDefragStats().tries, 0);
+    EXPECT_GT(GetMallocCurrentCommitted(), NUMBER_OF_KEYS);
+  });
+}
+
 // TODO: to test transactions with a single shard since then all transactions become local.
 // To consider having a parameter in dragonfly engine controlling number of shards
 // unconditionally from number of cpus. TO TEST BLPOP under multi for single/multi argument case.