rocksdb/table/sst_file_dumper.cc
Andrew Kryczka d904233d2f Limit buffering for collecting samples for compression dictionary (#7970)
Summary:
For dictionary compression, we need to collect some representative samples of the data to be compressed, which we use to either generate or train (when `CompressionOptions::zstd_max_train_bytes > 0`) a dictionary. Previously, the strategy was to buffer all the data blocks during flush, and up to the target file size during compaction. That strategy allowed us to randomly pick samples from as wide a range as possible that'd be guaranteed to land in a single output file.

However, some users try to make huge files in memory-constrained environments, where this strategy can cause OOM. This PR introduces an option, `CompressionOptions::max_dict_buffer_bytes`, that limits how much data blocks are buffered before we switch to unbuffered mode (which means creating the per-SST dictionary, writing out the buffered data, and compressing/writing new blocks as soon as they are built). It is not strict as we currently buffer more than just data blocks -- also keys are buffered. But it does make a step towards giving users predictable memory usage.

Related changes include:

- Changed sampling for dictionary compression to select unique data blocks when there is limited availability of data blocks
- Made use of `BlockBuilder::SwapAndReset()` to save an allocation+memcpy when buffering data blocks for building a dictionary
- Changed `ParseBoolean()` to accept an input containing characters after the boolean. This is necessary since, with this PR, a value for `CompressionOptions::enabled` is no longer necessarily the final component in the `CompressionOptions` string.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7970

Test Plan:
- updated `CompressionOptions` unit tests to verify limit is respected (to the extent expected in the current implementation) in various scenarios of flush/compaction to bottommost/non-bottommost level
- looked at jemalloc heap profiles right before and after switching to unbuffered mode during flush/compaction. Verified memory usage in buffering is proportional to the limit set.

Reviewed By: pdillinger

Differential Revision: D26467994

Pulled By: ajkr

fbshipit-source-id: 3da4ef9fba59974e4ef40e40c01611002c861465
2021-02-19 14:09:54 -08:00

504 lines
18 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
#ifndef ROCKSDB_LITE
#include "table/sst_file_dumper.h"
#include <chrono>
#include <cinttypes>
#include <iostream>
#include <map>
#include <memory>
#include <sstream>
#include <vector>
#include "db/blob/blob_index.h"
#include "db/memtable.h"
#include "db/write_batch_internal.h"
#include "options/cf_options.h"
#include "port/port.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/iterator.h"
#include "rocksdb/slice_transform.h"
#include "rocksdb/status.h"
#include "rocksdb/table_properties.h"
#include "rocksdb/utilities/ldb_cmd.h"
#include "table/block_based/block.h"
#include "table/block_based/block_based_table_builder.h"
#include "table/block_based/block_based_table_factory.h"
#include "table/block_based/block_builder.h"
#include "table/format.h"
#include "table/meta_blocks.h"
#include "table/plain/plain_table_factory.h"
#include "table/table_reader.h"
#include "util/compression.h"
#include "util/random.h"
namespace ROCKSDB_NAMESPACE {
SstFileDumper::SstFileDumper(const Options& options,
const std::string& file_path,
size_t readahead_size, bool verify_checksum,
bool output_hex, bool decode_blob_index,
const EnvOptions& soptions, bool silent)
: file_name_(file_path),
read_num_(0),
output_hex_(output_hex),
decode_blob_index_(decode_blob_index),
soptions_(soptions),
silent_(silent),
options_(options),
ioptions_(options_),
moptions_(ColumnFamilyOptions(options_)),
read_options_(verify_checksum, false),
internal_comparator_(BytewiseComparator()) {
read_options_.readahead_size = readahead_size;
if (!silent_) {
fprintf(stdout, "Process %s\n", file_path.c_str());
}
init_result_ = GetTableReader(file_name_);
}
extern const uint64_t kBlockBasedTableMagicNumber;
extern const uint64_t kLegacyBlockBasedTableMagicNumber;
extern const uint64_t kPlainTableMagicNumber;
extern const uint64_t kLegacyPlainTableMagicNumber;
const char* testFileName = "test_file_name";
Status SstFileDumper::GetTableReader(const std::string& file_path) {
// Warning about 'magic_number' being uninitialized shows up only in UBsan
// builds. Though access is guarded by 's.ok()' checks, fix the issue to
// avoid any warnings.
uint64_t magic_number = Footer::kInvalidTableMagicNumber;
// read table magic number
Footer footer;
const auto& fs = options_.env->GetFileSystem();
std::unique_ptr<FSRandomAccessFile> file;
uint64_t file_size = 0;
Status s = fs->NewRandomAccessFile(file_path, FileOptions(soptions_), &file,
nullptr);
if (s.ok()) {
s = fs->GetFileSize(file_path, IOOptions(), &file_size, nullptr);
}
// check empty file
// if true, skip further processing of this file
if (file_size == 0) {
return Status::Aborted(file_path, "Empty file");
}
file_.reset(new RandomAccessFileReader(std::move(file), file_path));
FilePrefetchBuffer prefetch_buffer(nullptr, 0, 0, true /* enable */,
false /* track_min_offset */);
if (s.ok()) {
const uint64_t kSstDumpTailPrefetchSize = 512 * 1024;
uint64_t prefetch_size = (file_size > kSstDumpTailPrefetchSize)
? kSstDumpTailPrefetchSize
: file_size;
uint64_t prefetch_off = file_size - prefetch_size;
IOOptions opts;
s = prefetch_buffer.Prefetch(opts, file_.get(), prefetch_off,
static_cast<size_t>(prefetch_size));
s = ReadFooterFromFile(opts, file_.get(), &prefetch_buffer, file_size,
&footer);
}
if (s.ok()) {
magic_number = footer.table_magic_number();
}
if (s.ok()) {
if (magic_number == kPlainTableMagicNumber ||
magic_number == kLegacyPlainTableMagicNumber) {
soptions_.use_mmap_reads = true;
fs->NewRandomAccessFile(file_path, FileOptions(soptions_), &file,
nullptr);
file_.reset(new RandomAccessFileReader(std::move(file), file_path));
}
options_.comparator = &internal_comparator_;
// For old sst format, ReadTableProperties might fail but file can be read
if (ReadTableProperties(magic_number, file_.get(), file_size,
(magic_number == kBlockBasedTableMagicNumber)
? &prefetch_buffer
: nullptr)
.ok()) {
s = SetTableOptionsByMagicNumber(magic_number);
} else {
s = SetOldTableOptions();
}
}
if (s.ok()) {
s = NewTableReader(ioptions_, soptions_, internal_comparator_, file_size,
&table_reader_);
}
return s;
}
Status SstFileDumper::NewTableReader(
const ImmutableCFOptions& /*ioptions*/, const EnvOptions& /*soptions*/,
const InternalKeyComparator& /*internal_comparator*/, uint64_t file_size,
std::unique_ptr<TableReader>* /*table_reader*/) {
auto t_opt =
TableReaderOptions(ioptions_, moptions_.prefix_extractor.get(), soptions_,
internal_comparator_, false /* skip_filters */,
false /* imortal */, true /* force_direct_prefetch */);
// Allow open file with global sequence number for backward compatibility.
t_opt.largest_seqno = kMaxSequenceNumber;
// We need to turn off pre-fetching of index and filter nodes for
// BlockBasedTable
if (options_.table_factory->IsInstanceOf(
TableFactory::kBlockBasedTableName())) {
return options_.table_factory->NewTableReader(t_opt, std::move(file_),
file_size, &table_reader_,
/*enable_prefetch=*/false);
}
// For all other factory implementation
return options_.table_factory->NewTableReader(t_opt, std::move(file_),
file_size, &table_reader_);
}
Status SstFileDumper::VerifyChecksum() {
// We could pass specific readahead setting into read options if needed.
return table_reader_->VerifyChecksum(read_options_,
TableReaderCaller::kSSTDumpTool);
}
Status SstFileDumper::DumpTable(const std::string& out_filename) {
std::unique_ptr<WritableFile> out_file;
Env* env = options_.env;
Status s = env->NewWritableFile(out_filename, &out_file, soptions_);
if (s.ok()) {
s = table_reader_->DumpTable(out_file.get());
}
if (!s.ok()) {
// close the file before return error, ignore the close error if there's any
out_file->Close().PermitUncheckedError();
return s;
}
return out_file->Close();
}
Status SstFileDumper::CalculateCompressedTableSize(
const TableBuilderOptions& tb_options, size_t block_size,
uint64_t* num_data_blocks, uint64_t* compressed_table_size) {
std::unique_ptr<Env> env(NewMemEnv(options_.env));
std::unique_ptr<WritableFileWriter> dest_writer;
Status s =
WritableFileWriter::Create(env->GetFileSystem(), testFileName,
FileOptions(soptions_), &dest_writer, nullptr);
if (!s.ok()) {
return s;
}
BlockBasedTableOptions table_options;
table_options.block_size = block_size;
BlockBasedTableFactory block_based_tf(table_options);
std::unique_ptr<TableBuilder> table_builder;
table_builder.reset(block_based_tf.NewTableBuilder(
tb_options,
TablePropertiesCollectorFactory::Context::kUnknownColumnFamily,
dest_writer.get()));
std::unique_ptr<InternalIterator> iter(table_reader_->NewIterator(
read_options_, moptions_.prefix_extractor.get(), /*arena=*/nullptr,
/*skip_filters=*/false, TableReaderCaller::kSSTDumpTool));
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
table_builder->Add(iter->key(), iter->value());
}
s = iter->status();
if (!s.ok()) {
return s;
}
s = table_builder->Finish();
if (!s.ok()) {
return s;
}
*compressed_table_size = table_builder->FileSize();
assert(num_data_blocks != nullptr);
*num_data_blocks = table_builder->GetTableProperties().num_data_blocks;
return env->DeleteFile(testFileName);
}
Status SstFileDumper::ShowAllCompressionSizes(
size_t block_size,
const std::vector<std::pair<CompressionType, const char*>>&
compression_types,
int32_t compress_level_from, int32_t compress_level_to,
uint32_t max_dict_bytes, uint32_t zstd_max_train_bytes,
uint64_t max_dict_buffer_bytes) {
fprintf(stdout, "Block Size: %" ROCKSDB_PRIszt "\n", block_size);
for (auto& i : compression_types) {
if (CompressionTypeSupported(i.first)) {
fprintf(stdout, "Compression: %-24s\n", i.second);
CompressionOptions compress_opt;
compress_opt.max_dict_bytes = max_dict_bytes;
compress_opt.zstd_max_train_bytes = zstd_max_train_bytes;
compress_opt.max_dict_buffer_bytes = max_dict_buffer_bytes;
for (int32_t j = compress_level_from; j <= compress_level_to; j++) {
fprintf(stdout, "Compression level: %d", j);
compress_opt.level = j;
Status s = ShowCompressionSize(block_size, i.first, compress_opt);
if (!s.ok()) {
return s;
}
}
} else {
fprintf(stdout, "Unsupported compression type: %s.\n", i.second);
}
}
return Status::OK();
}
Status SstFileDumper::ShowCompressionSize(
size_t block_size, CompressionType compress_type,
const CompressionOptions& compress_opt) {
Options opts;
opts.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
opts.statistics->set_stats_level(StatsLevel::kAll);
const ImmutableCFOptions imoptions(opts);
const ColumnFamilyOptions cfo(opts);
const MutableCFOptions moptions(cfo);
ROCKSDB_NAMESPACE::InternalKeyComparator ikc(opts.comparator);
std::vector<std::unique_ptr<IntTblPropCollectorFactory>>
block_based_table_factories;
std::string column_family_name;
int unknown_level = -1;
TableBuilderOptions tb_opts(
imoptions, moptions, ikc, &block_based_table_factories, compress_type,
0 /* sample_for_compression */, compress_opt, false /* skip_filters */,
column_family_name, unknown_level);
uint64_t num_data_blocks = 0;
std::chrono::steady_clock::time_point start =
std::chrono::steady_clock::now();
uint64_t file_size;
Status s = CalculateCompressedTableSize(tb_opts, block_size, &num_data_blocks,
&file_size);
if (!s.ok()) {
return s;
}
std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
fprintf(stdout, " Size: %10" PRIu64, file_size);
fprintf(stdout, " Blocks: %6" PRIu64, num_data_blocks);
fprintf(stdout, " Time Taken: %10s microsecs",
std::to_string(
std::chrono::duration_cast<std::chrono::microseconds>(end - start)
.count())
.c_str());
const uint64_t compressed_blocks =
opts.statistics->getAndResetTickerCount(NUMBER_BLOCK_COMPRESSED);
const uint64_t not_compressed_blocks =
opts.statistics->getAndResetTickerCount(NUMBER_BLOCK_NOT_COMPRESSED);
// When the option enable_index_compression is true,
// NUMBER_BLOCK_COMPRESSED is incremented for index block(s).
if ((compressed_blocks + not_compressed_blocks) > num_data_blocks) {
num_data_blocks = compressed_blocks + not_compressed_blocks;
}
const uint64_t ratio_not_compressed_blocks =
(num_data_blocks - compressed_blocks) - not_compressed_blocks;
const double compressed_pcnt =
(0 == num_data_blocks) ? 0.0
: ((static_cast<double>(compressed_blocks) /
static_cast<double>(num_data_blocks)) *
100.0);
const double ratio_not_compressed_pcnt =
(0 == num_data_blocks)
? 0.0
: ((static_cast<double>(ratio_not_compressed_blocks) /
static_cast<double>(num_data_blocks)) *
100.0);
const double not_compressed_pcnt =
(0 == num_data_blocks) ? 0.0
: ((static_cast<double>(not_compressed_blocks) /
static_cast<double>(num_data_blocks)) *
100.0);
fprintf(stdout, " Compressed: %6" PRIu64 " (%5.1f%%)", compressed_blocks,
compressed_pcnt);
fprintf(stdout, " Not compressed (ratio): %6" PRIu64 " (%5.1f%%)",
ratio_not_compressed_blocks, ratio_not_compressed_pcnt);
fprintf(stdout, " Not compressed (abort): %6" PRIu64 " (%5.1f%%)\n",
not_compressed_blocks, not_compressed_pcnt);
return Status::OK();
}
Status SstFileDumper::ReadTableProperties(uint64_t table_magic_number,
RandomAccessFileReader* file,
uint64_t file_size,
FilePrefetchBuffer* prefetch_buffer) {
TableProperties* table_properties = nullptr;
Status s = ROCKSDB_NAMESPACE::ReadTableProperties(
file, file_size, table_magic_number, ioptions_, &table_properties,
/* compression_type_missing= */ false,
/* memory_allocator= */ nullptr, prefetch_buffer);
if (s.ok()) {
table_properties_.reset(table_properties);
} else {
if (!silent_) {
fprintf(stdout, "Not able to read table properties\n");
}
}
return s;
}
Status SstFileDumper::SetTableOptionsByMagicNumber(
uint64_t table_magic_number) {
assert(table_properties_);
if (table_magic_number == kBlockBasedTableMagicNumber ||
table_magic_number == kLegacyBlockBasedTableMagicNumber) {
BlockBasedTableFactory* bbtf = new BlockBasedTableFactory();
// To force tail prefetching, we fake reporting two useful reads of 512KB
// from the tail.
// It needs at least two data points to warm up the stats.
bbtf->tail_prefetch_stats()->RecordEffectiveSize(512 * 1024);
bbtf->tail_prefetch_stats()->RecordEffectiveSize(512 * 1024);
options_.table_factory.reset(bbtf);
if (!silent_) {
fprintf(stdout, "Sst file format: block-based\n");
}
auto& props = table_properties_->user_collected_properties;
auto pos = props.find(BlockBasedTablePropertyNames::kIndexType);
if (pos != props.end()) {
auto index_type_on_file = static_cast<BlockBasedTableOptions::IndexType>(
DecodeFixed32(pos->second.c_str()));
if (index_type_on_file ==
BlockBasedTableOptions::IndexType::kHashSearch) {
options_.prefix_extractor.reset(NewNoopTransform());
}
}
} else if (table_magic_number == kPlainTableMagicNumber ||
table_magic_number == kLegacyPlainTableMagicNumber) {
options_.allow_mmap_reads = true;
PlainTableOptions plain_table_options;
plain_table_options.user_key_len = kPlainTableVariableLength;
plain_table_options.bloom_bits_per_key = 0;
plain_table_options.hash_table_ratio = 0;
plain_table_options.index_sparseness = 1;
plain_table_options.huge_page_tlb_size = 0;
plain_table_options.encoding_type = kPlain;
plain_table_options.full_scan_mode = true;
options_.table_factory.reset(NewPlainTableFactory(plain_table_options));
if (!silent_) {
fprintf(stdout, "Sst file format: plain table\n");
}
} else {
char error_msg_buffer[80];
snprintf(error_msg_buffer, sizeof(error_msg_buffer) - 1,
"Unsupported table magic number --- %lx",
(long)table_magic_number);
return Status::InvalidArgument(error_msg_buffer);
}
return Status::OK();
}
Status SstFileDumper::SetOldTableOptions() {
assert(table_properties_ == nullptr);
options_.table_factory = std::make_shared<BlockBasedTableFactory>();
if (!silent_) {
fprintf(stdout, "Sst file format: block-based(old version)\n");
}
return Status::OK();
}
Status SstFileDumper::ReadSequential(bool print_kv, uint64_t read_num,
bool has_from, const std::string& from_key,
bool has_to, const std::string& to_key,
bool use_from_as_prefix) {
if (!table_reader_) {
return init_result_;
}
InternalIterator* iter = table_reader_->NewIterator(
read_options_, moptions_.prefix_extractor.get(),
/*arena=*/nullptr, /*skip_filters=*/false,
TableReaderCaller::kSSTDumpTool);
uint64_t i = 0;
if (has_from) {
InternalKey ikey;
ikey.SetMinPossibleForUserKey(from_key);
iter->Seek(ikey.Encode());
} else {
iter->SeekToFirst();
}
for (; iter->Valid(); iter->Next()) {
Slice key = iter->key();
Slice value = iter->value();
++i;
if (read_num > 0 && i > read_num) break;
ParsedInternalKey ikey;
Status pik_status = ParseInternalKey(key, &ikey, true /* log_err_key */);
if (!pik_status.ok()) {
std::cerr << pik_status.getState() << "\n";
continue;
}
// the key returned is not prefixed with out 'from' key
if (use_from_as_prefix && !ikey.user_key.starts_with(from_key)) {
break;
}
// If end marker was specified, we stop before it
if (has_to && BytewiseComparator()->Compare(ikey.user_key, to_key) >= 0) {
break;
}
if (print_kv) {
if (!decode_blob_index_ || ikey.type != kTypeBlobIndex) {
fprintf(stdout, "%s => %s\n",
ikey.DebugString(true, output_hex_).c_str(),
value.ToString(output_hex_).c_str());
} else {
BlobIndex blob_index;
const Status s = blob_index.DecodeFrom(value);
if (!s.ok()) {
fprintf(stderr, "%s => error decoding blob index\n",
ikey.DebugString(true, output_hex_).c_str());
continue;
}
fprintf(stdout, "%s => %s\n",
ikey.DebugString(true, output_hex_).c_str(),
blob_index.DebugString(output_hex_).c_str());
}
}
}
read_num_ += i;
Status ret = iter->status();
delete iter;
return ret;
}
Status SstFileDumper::ReadTableProperties(
std::shared_ptr<const TableProperties>* table_properties) {
if (!table_reader_) {
return init_result_;
}
*table_properties = table_reader_->GetTableProperties();
return init_result_;
}
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE