309503855e
* Issue: Doris occasionally encounters an issue where memory usage becomes exceptionally high and does not decrease. The leaked memory is occupied by Bloom filters stored in memory. Reason: The segment cache stores segment objects read from files into memory. It functions as an LRU cache with an eviction strategy: when the number of segments exceeds the maximum number, or the total memory size of segment objects in the cache exceeds the maximum usage, it evicts the older segments. However, there is a piece of logic in the code that first reads the segment object into memory, assuming it occupies memory size A, then places the read segment object into the cache (at this point, the cache considers the segment object size to be A). It then reads the segment's Bloom filter from the file and assigns it to the segment's Bloom filter member variable, assuming the Bloom filter occupies memory size B. Thus, the total size of the segment object at this point is A+B. However, the cache does not update this size, leading to the actual size of the segment object stored in the cache (A+B) being larger than the size considered by the cache (A). When the number of segment objects in the cache increases to a certain extent, the used memory will surge dramatically. However, the cache does not perceive the size as reaching the eviction limit, so it does not evict the segment objects. In such cases, a memory leak issue arises. Solution: Since each segment object only reads the Bloom filter once, the issue can be resolved by changing the logic from reading the segment, placing it into the cache, and then reading the Bloom filter to reading the segment, reading the Bloom filter, and then placing it into the cache.
94 lines
3.4 KiB
C++
94 lines
3.4 KiB
C++
// Licensed to the Apache Software Foundation (ASF) under one
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// or more contributor license agreements. See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership. The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License. You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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#include "olap/segment_loader.h"
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#include "common/config.h"
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#include "common/status.h"
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#include "olap/olap_define.h"
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#include "olap/rowset/beta_rowset.h"
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#include "util/stopwatch.hpp"
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namespace doris {
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SegmentLoader* SegmentLoader::instance() {
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return ExecEnv::GetInstance()->segment_loader();
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}
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bool SegmentCache::lookup(const SegmentCache::CacheKey& key, SegmentCacheHandle* handle) {
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auto* lru_handle = LRUCachePolicy::lookup(key.encode());
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if (lru_handle == nullptr) {
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return false;
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}
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handle->push_segment(this, lru_handle);
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return true;
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}
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void SegmentCache::insert(const SegmentCache::CacheKey& key, SegmentCache::CacheValue& value,
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SegmentCacheHandle* handle) {
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auto* lru_handle =
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LRUCachePolicy::insert(key.encode(), &value, value.segment->meta_mem_usage(),
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value.segment->meta_mem_usage(), CachePriority::NORMAL);
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handle->push_segment(this, lru_handle);
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}
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void SegmentCache::erase(const SegmentCache::CacheKey& key) {
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LRUCachePolicy::erase(key.encode());
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}
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Status SegmentLoader::load_segments(const BetaRowsetSharedPtr& rowset,
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SegmentCacheHandle* cache_handle, bool use_cache,
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bool need_load_pk_index_and_bf) {
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if (cache_handle->is_inited()) {
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return Status::OK();
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}
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for (int64_t i = 0; i < rowset->num_segments(); i++) {
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SegmentCache::CacheKey cache_key(rowset->rowset_id(), i);
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if (_segment_cache->lookup(cache_key, cache_handle)) {
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continue;
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}
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segment_v2::SegmentSharedPtr segment;
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RETURN_IF_ERROR(rowset->load_segment(i, &segment));
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if (need_load_pk_index_and_bf) {
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RETURN_IF_ERROR(segment->load_pk_index_and_bf());
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}
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if (use_cache && !config::disable_segment_cache) {
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// memory of SegmentCache::CacheValue will be handled by SegmentCache
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auto* cache_value = new SegmentCache::CacheValue();
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_cache_mem_usage += segment->meta_mem_usage();
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cache_value->segment = std::move(segment);
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_segment_cache->insert(cache_key, *cache_value, cache_handle);
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} else {
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cache_handle->push_segment(std::move(segment));
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}
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}
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cache_handle->set_inited();
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return Status::OK();
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}
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void SegmentLoader::erase_segment(const SegmentCache::CacheKey& key) {
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_segment_cache->erase(key);
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}
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void SegmentLoader::erase_segments(const RowsetId& rowset_id, int64_t num_segments) {
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for (int64_t i = 0; i < num_segments; i++) {
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erase_segment(SegmentCache::CacheKey(rowset_id, i));
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}
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}
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} // namespace doris
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