rocksdb/util/status.cc
Peter Dillinger 249eff0f30 Stats for redundant insertions into block cache (#6681)
Summary:
Since read threads do not coordinate on loading data into block
cache, two threads between Lookup and Insert can end up loading and
inserting the same data. This is particularly concerning with
cache_index_and_filter_blocks since those are hot and more likely to
be race targets if ejected from (or not pre-populated in) the cache.

Particularly with moves toward disaggregated / network storage, the cost
of redundant retrieval might be high, and we should at least have some
hard statistics from which we can estimate impact.

Example with full filter thrashing "cliff":

    $ ./db_bench --benchmarks=fillrandom --num=15000000 --cache_index_and_filter_blocks -bloom_bits=10
    ...
    $ ./db_bench --db=/tmp/rocksdbtest-172704/dbbench --use_existing_db --benchmarks=readrandom,stats --num=200000 --cache_index_and_filter_blocks --cache_size=$((130 * 1024 * 1024)) --bloom_bits=10 --threads=16 -statistics 2>&1 | egrep '^rocksdb.block.cache.(.*add|.*redundant)' | grep -v compress | sort
    rocksdb.block.cache.add COUNT : 14181
    rocksdb.block.cache.add.failures COUNT : 0
    rocksdb.block.cache.add.redundant COUNT : 476
    rocksdb.block.cache.data.add COUNT : 12749
    rocksdb.block.cache.data.add.redundant COUNT : 18
    rocksdb.block.cache.filter.add COUNT : 1003
    rocksdb.block.cache.filter.add.redundant COUNT : 217
    rocksdb.block.cache.index.add COUNT : 429
    rocksdb.block.cache.index.add.redundant COUNT : 241
    $ ./db_bench --db=/tmp/rocksdbtest-172704/dbbench --use_existing_db --benchmarks=readrandom,stats --num=200000 --cache_index_and_filter_blocks --cache_size=$((120 * 1024 * 1024)) --bloom_bits=10 --threads=16 -statistics 2>&1 | egrep '^rocksdb.block.cache.(.*add|.*redundant)' | grep -v compress | sort
    rocksdb.block.cache.add COUNT : 1182223
    rocksdb.block.cache.add.failures COUNT : 0
    rocksdb.block.cache.add.redundant COUNT : 302728
    rocksdb.block.cache.data.add COUNT : 31425
    rocksdb.block.cache.data.add.redundant COUNT : 12
    rocksdb.block.cache.filter.add COUNT : 795455
    rocksdb.block.cache.filter.add.redundant COUNT : 130238
    rocksdb.block.cache.index.add COUNT : 355343
    rocksdb.block.cache.index.add.redundant COUNT : 172478
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6681

Test Plan: Some manual testing (above) and unit test covering key metrics is included

Reviewed By: ltamasi

Differential Revision: D21134113

Pulled By: pdillinger

fbshipit-source-id: c11497b5f00f4ffdfe919823904e52d0a1a91d87
2020-04-27 13:20:27 -07:00

145 lines
4.3 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "rocksdb/status.h"
#include <stdio.h>
#ifdef OS_WIN
#include <string.h>
#endif
#include <cstring>
#include "port/port.h"
namespace ROCKSDB_NAMESPACE {
const char* Status::CopyState(const char* state) {
#ifdef OS_WIN
const size_t cch = std::strlen(state) + 1; // +1 for the null terminator
char* result = new char[cch];
errno_t ret
#if defined(_MSC_VER)
;
#else
__attribute__((__unused__));
#endif
ret = strncpy_s(result, cch, state, cch - 1);
result[cch - 1] = '\0';
assert(ret == 0);
return result;
#else
const size_t cch = std::strlen(state) + 1; // +1 for the null terminator
return std::strncpy(new char[cch], state, cch);
#endif
}
static const char* msgs[static_cast<int>(Status::kMaxSubCode)] = {
"", // kNone
"Timeout Acquiring Mutex", // kMutexTimeout
"Timeout waiting to lock key", // kLockTimeout
"Failed to acquire lock due to max_num_locks limit", // kLockLimit
"No space left on device", // kNoSpace
"Deadlock", // kDeadlock
"Stale file handle", // kStaleFile
"Memory limit reached", // kMemoryLimit
"Space limit reached", // kSpaceLimit
"No such file or directory", // kPathNotFound
// KMergeOperandsInsufficientCapacity
"Insufficient capacity for merge operands",
// kManualCompactionPaused
"Manual compaction paused",
" (overwritten)", // kOverwritten, subcode of OK
};
Status::Status(Code _code, SubCode _subcode, const Slice& msg,
const Slice& msg2)
: code_(_code), subcode_(_subcode), sev_(kNoError) {
assert(code_ != kOk);
assert(subcode_ != kMaxSubCode);
const size_t len1 = msg.size();
const size_t len2 = msg2.size();
const size_t size = len1 + (len2 ? (2 + len2) : 0);
char* const result = new char[size + 1]; // +1 for null terminator
memcpy(result, msg.data(), len1);
if (len2) {
result[len1] = ':';
result[len1 + 1] = ' ';
memcpy(result + len1 + 2, msg2.data(), len2);
}
result[size] = '\0'; // null terminator for C style string
state_ = result;
}
std::string Status::ToString() const {
char tmp[30];
const char* type;
switch (code_) {
case kOk:
return "OK";
case kNotFound:
type = "NotFound: ";
break;
case kCorruption:
type = "Corruption: ";
break;
case kNotSupported:
type = "Not implemented: ";
break;
case kInvalidArgument:
type = "Invalid argument: ";
break;
case kIOError:
type = "IO error: ";
break;
case kMergeInProgress:
type = "Merge in progress: ";
break;
case kIncomplete:
type = "Result incomplete: ";
break;
case kShutdownInProgress:
type = "Shutdown in progress: ";
break;
case kTimedOut:
type = "Operation timed out: ";
break;
case kAborted:
type = "Operation aborted: ";
break;
case kBusy:
type = "Resource busy: ";
break;
case kExpired:
type = "Operation expired: ";
break;
case kTryAgain:
type = "Operation failed. Try again.: ";
break;
case kColumnFamilyDropped:
type = "Column family dropped: ";
break;
default:
snprintf(tmp, sizeof(tmp), "Unknown code(%d): ",
static_cast<int>(code()));
type = tmp;
break;
}
std::string result(type);
if (subcode_ != kNone) {
uint32_t index = static_cast<int32_t>(subcode_);
assert(sizeof(msgs) > index);
result.append(msgs[index]);
}
if (state_ != nullptr) {
result.append(state_);
}
return result;
}
} // namespace ROCKSDB_NAMESPACE