Dynamic max_total_wal_size option

Summary: Closes facebook#1509

Differential Revision: D4176426

Pulled By: yiwu-arbug

fbshipit-source-id: b57689d

HISTORY.md

@@ -2,7 +2,7 @@
 ## Unreleased
 ### Public API Change
 * Options::max_bytes_for_level_multiplier is now a double along with all getters and setters.
-* Suppor dynamically change `delayed_write_rate` option via SetDBOptions().
+* Support dynamically change `delayed_write_rate` and `max_total_wal_size` options via SetDBOptions().
 
 ### New Features
 * Add avoid_flush_during_shutdown option, which speeds up DB shutdown by not flushing unpersisted data (i.e. with disableWAL = true). Unpersisted data will be lost. The options is dynamically changeable via SetDBOptions().

db/db_impl.cc

@@ -2493,6 +2493,10 @@ Status DBImpl::SetDBOptions(
 
       mutable_db_options_ = new_options;
 
+      if (total_log_size_ > GetMaxTotalWalSize()) {
+        FlushColumnFamilies();
+      }
+
       persist_options_status = PersistOptions();
     }
   }
@@ -3769,11 +3773,12 @@ bool DBImpl::MCOverlap(ManualCompaction* m, ManualCompaction* m1) {
 }
 
 size_t DBImpl::GetWalPreallocateBlockSize(uint64_t write_buffer_size) const {
+  mutex_.AssertHeld();
   size_t bsize = write_buffer_size / 10 + write_buffer_size;
   // Some users might set very high write_buffer_size and rely on
   // max_total_wal_size or other parameters to control the WAL size.
-  if (immutable_db_options_.max_total_wal_size > 0) {
-    bsize = std::min<size_t>(bsize, immutable_db_options_.max_total_wal_size);
+  if (mutable_db_options_.max_total_wal_size > 0) {
+    bsize = std::min<size_t>(bsize, mutable_db_options_.max_total_wal_size);
   }
   if (immutable_db_options_.db_write_buffer_size > 0) {
     bsize = std::min<size_t>(bsize, immutable_db_options_.db_write_buffer_size);
@@ -4676,34 +4681,10 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
   assert(!single_column_family_mode_ ||
          versions_->GetColumnFamilySet()->NumberOfColumnFamilies() == 1);
 
-  uint64_t max_total_wal_size = (immutable_db_options_.max_total_wal_size == 0)
-                                    ? 4 * max_total_in_memory_state_
-                                    : immutable_db_options_.max_total_wal_size;
   if (UNLIKELY(!single_column_family_mode_ &&
-               alive_log_files_.begin()->getting_flushed == false &&
-               total_log_size_ > max_total_wal_size)) {
-    uint64_t flush_column_family_if_log_file = alive_log_files_.begin()->number;
-    alive_log_files_.begin()->getting_flushed = true;
-    Log(InfoLogLevel::INFO_LEVEL, immutable_db_options_.info_log,
-        "Flushing all column families with data in WAL number %" PRIu64
-        ". Total log size is %" PRIu64 " while max_total_wal_size is %" PRIu64,
-        flush_column_family_if_log_file, total_log_size_, max_total_wal_size);
-    // no need to refcount because drop is happening in write thread, so can't
-    // happen while we're in the write thread
-    for (auto cfd : *versions_->GetColumnFamilySet()) {
-      if (cfd->IsDropped()) {
-        continue;
-      }
-      if (cfd->GetLogNumber() <= flush_column_family_if_log_file) {
-        status = SwitchMemtable(cfd, &context);
-        if (!status.ok()) {
-          break;
-        }
-        cfd->imm()->FlushRequested();
-        SchedulePendingFlush(cfd);
-      }
-    }
-    MaybeScheduleFlushOrCompaction();
+               !alive_log_files_.begin()->getting_flushed &&
+               total_log_size_ > GetMaxTotalWalSize())) {
+    FlushColumnFamilies();
   } else if (UNLIKELY(write_buffer_manager_->ShouldFlush())) {
     // Before a new memtable is added in SwitchMemtable(),
     // write_buffer_manager_->ShouldFlush() will keep returning true. If another
@@ -5020,6 +5001,46 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
   return status;
 }
 
+void DBImpl::FlushColumnFamilies() {
+  mutex_.AssertHeld();
+
+  WriteContext context;
+
+  if (alive_log_files_.begin()->getting_flushed) {
+    return;
+  }
+
+  uint64_t flush_column_family_if_log_file = alive_log_files_.begin()->number;
+  alive_log_files_.begin()->getting_flushed = true;
+  Log(InfoLogLevel::INFO_LEVEL, immutable_db_options_.info_log,
+      "Flushing all column families with data in WAL number %" PRIu64
+      ". Total log size is %" PRIu64 " while max_total_wal_size is %" PRIu64,
+      flush_column_family_if_log_file, total_log_size_, GetMaxTotalWalSize());
+  // no need to refcount because drop is happening in write thread, so can't
+  // happen while we're in the write thread
+  for (auto cfd : *versions_->GetColumnFamilySet()) {
+    if (cfd->IsDropped()) {
+      continue;
+    }
+    if (cfd->GetLogNumber() <= flush_column_family_if_log_file) {
+      auto status = SwitchMemtable(cfd, &context);
+      if (!status.ok()) {
+        break;
+      }
+      cfd->imm()->FlushRequested();
+      SchedulePendingFlush(cfd);
+    }
+  }
+  MaybeScheduleFlushOrCompaction();
+}
+
+uint64_t DBImpl::GetMaxTotalWalSize() const {
+  mutex_.AssertHeld();
+  return mutable_db_options_.max_total_wal_size == 0
+             ? 4 * max_total_in_memory_state_
+             : mutable_db_options_.max_total_wal_size;
+}
+
 // REQUIRES: mutex_ is held
 // REQUIRES: this thread is currently at the front of the writer queue
 Status DBImpl::DelayWrite(uint64_t num_bytes) {
@@ -5119,6 +5140,8 @@ Status DBImpl::SwitchMemtable(ColumnFamilyData* cfd, WriteContext* context) {
   int num_imm_unflushed = cfd->imm()->NumNotFlushed();
   DBOptions db_options =
       BuildDBOptions(immutable_db_options_, mutable_db_options_);
+  const auto preallocate_block_size =
+    GetWalPreallocateBlockSize(mutable_cf_options.write_buffer_size);
   mutex_.Unlock();
   Status s;
   {
@@ -5140,8 +5163,10 @@ Status DBImpl::SwitchMemtable(ColumnFamilyData* cfd, WriteContext* context) {
       if (s.ok()) {
         // Our final size should be less than write_buffer_size
         // (compression, etc) but err on the side of caution.
-        lfile->SetPreallocationBlockSize(
-            GetWalPreallocateBlockSize(mutable_cf_options.write_buffer_size));
+
+        // use preallocate_block_size instead
+        // of calling GetWalPreallocateBlockSize()
+        lfile->SetPreallocationBlockSize(preallocate_block_size);
         unique_ptr<WritableFileWriter> file_writer(
             new WritableFileWriter(std::move(lfile), opt_env_opt));
         new_log =

db/db_impl.h

@@ -728,6 +728,10 @@ class DBImpl : public DB {
   // REQUIRES: mutex locked
   Status PersistOptions();
 
+  void FlushColumnFamilies();
+
+  uint64_t GetMaxTotalWalSize() const;
+
   // table_cache_ provides its own synchronization
   std::shared_ptr<Cache> table_cache_;
 

db/db_options_test.cc

@@ -289,6 +289,33 @@ TEST_F(DBOptionsTest, SetDelayedWriteRateOption) {
   ASSERT_EQ(20000, dbfull()->TEST_write_controler().max_delayed_write_rate());
 }
 
+TEST_F(DBOptionsTest, MaxTotalWalSizeChange) {
+  Random rnd(1044);
+  const auto value_size = size_t(1024);
+  std::string value;
+  test::RandomString(&rnd, value_size, &value);
+
+  Options options;
+  options.create_if_missing = true;
+  CreateColumnFamilies({"1", "2", "3"}, options);
+  ReopenWithColumnFamilies({"default", "1", "2", "3"}, options);
+
+  WriteOptions write_options;
+
+  const int key_count = 100;
+  for (int i = 0; i < key_count; ++i) {
+    for (size_t cf = 0; cf < handles_.size(); ++cf) {
+      ASSERT_OK(Put(static_cast<int>(cf), Key(i), value));
+    }
+  }
+  ASSERT_OK(dbfull()->SetDBOptions({{"max_total_wal_size", "10"}}));
+
+  for (size_t cf = 0; cf < handles_.size(); ++cf) {
+    dbfull()->TEST_WaitForFlushMemTable(handles_[cf]);
+    ASSERT_EQ("1", FilesPerLevel(static_cast<int>(cf)));
+  }
+}
+
 #endif  // ROCKSDB_LITE
 
 }  // namespace rocksdb

util/db_options.cc

@@ -33,7 +33,6 @@ ImmutableDBOptions::ImmutableDBOptions(const DBOptions& options)
       info_log_level(options.info_log_level),
       max_open_files(options.max_open_files),
       max_file_opening_threads(options.max_file_opening_threads),
-      max_total_wal_size(options.max_total_wal_size),
       statistics(options.statistics),
       disable_data_sync(options.disableDataSync),
       use_fsync(options.use_fsync),
@@ -105,8 +104,6 @@ void ImmutableDBOptions::Dump(Logger* log) const {
          max_open_files);
   Header(log, "               Options.max_file_opening_threads: %d",
          max_file_opening_threads);
-  Header(log, "                     Options.max_total_wal_size: %" PRIu64,
-         max_total_wal_size);
   Header(log, "                        Options.disableDataSync: %d",
          disable_data_sync);
   Header(log, "                              Options.use_fsync: %d", use_fsync);
@@ -224,13 +221,15 @@ MutableDBOptions::MutableDBOptions()
     : base_background_compactions(1),
       max_background_compactions(1),
       avoid_flush_during_shutdown(false),
-      delayed_write_rate(2 * 1024U * 1024U) {}
+      delayed_write_rate(2 * 1024U * 1024U),
+      max_total_wal_size(0) {}
 
 MutableDBOptions::MutableDBOptions(const DBOptions& options)
     : base_background_compactions(options.base_background_compactions),
       max_background_compactions(options.max_background_compactions),
       avoid_flush_during_shutdown(options.avoid_flush_during_shutdown),
-      delayed_write_rate(options.delayed_write_rate) {}
+      delayed_write_rate(options.delayed_write_rate),
+      max_total_wal_size(options.max_total_wal_size) {}
 
 void MutableDBOptions::Dump(Logger* log) const {
   Header(log, "            Options.base_background_compactions: %d",
@@ -241,6 +240,8 @@ void MutableDBOptions::Dump(Logger* log) const {
          avoid_flush_during_shutdown);
   Header(log, "            Options.delayed_write_rate : %" PRIu64,
          delayed_write_rate);
+  Header(log, "            Options.max_total_wal_size: %" PRIu64,
+         max_total_wal_size);
 }
 
 }  // namespace rocksdb

util/db_options.h

@@ -29,7 +29,6 @@ struct ImmutableDBOptions {
   InfoLogLevel info_log_level;
   int max_open_files;
   int max_file_opening_threads;
-  uint64_t max_total_wal_size;
   std::shared_ptr<Statistics> statistics;
   bool disable_data_sync;
   bool use_fsync;
@@ -95,6 +94,7 @@ struct MutableDBOptions {
   int max_background_compactions;
   bool avoid_flush_during_shutdown;
   uint64_t delayed_write_rate;
+  uint64_t max_total_wal_size;
 };
 
 }  // namespace rocksdb

util/options_helper.cc

@@ -45,7 +45,7 @@ DBOptions BuildDBOptions(const ImmutableDBOptions& immutable_db_options,
   options.max_open_files = immutable_db_options.max_open_files;
   options.max_file_opening_threads =
       immutable_db_options.max_file_opening_threads;
-  options.max_total_wal_size = immutable_db_options.max_total_wal_size;
+  options.max_total_wal_size = mutable_db_options.max_total_wal_size;
   options.statistics = immutable_db_options.statistics;
   options.disableDataSync = immutable_db_options.disable_data_sync;
   options.use_fsync = immutable_db_options.use_fsync;

util/options_helper.h

@@ -308,7 +308,8 @@ static std::unordered_map<std::string, OptionTypeInfo> db_options_type_info = {
       OptionVerificationType::kNormal, false, 0}},
     {"max_total_wal_size",
      {offsetof(struct DBOptions, max_total_wal_size), OptionType::kUInt64T,
-      OptionVerificationType::kNormal, false, 0}},
+      OptionVerificationType::kNormal, true,
+      offsetof(struct MutableDBOptions, max_total_wal_size)}},
     {"wal_bytes_per_sync",
      {offsetof(struct DBOptions, wal_bytes_per_sync), OptionType::kUInt64T,
       OptionVerificationType::kNormal, false, 0}},
@@ -710,4 +711,3 @@ extern const std::string kNullptrString;
 #endif  // !ROCKSDB_LITE
 
 }  // namespace rocksdb
-