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[Enhancement] Avoid acquire multiple lock in the same stack for tablet report #55808

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[Enhancement] Avoid acquire multiple lock in the same stack for tablet report #55808

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85890ad
[Enhancement] Avoid multiple lock acquire in the same stack for table…
srlch Feb 11, 2025
63377b8
add UT
srlch Feb 12, 2025
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11 changes: 8 additions & 3 deletions be/src/storage/tablet.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1534,6 +1534,13 @@ bool Tablet::_contains_rowset(const RowsetId rowset_id) {
}

void Tablet::build_tablet_report_info(TTabletInfo* tablet_info) {
// primary key specified info will protected by independent lock context
// in TabletUpdates which means that those lock context can be sperated from
// the tablet meta_lock when trying to get the extra info
if (_updates) {
_updates->get_tablet_info_extra(tablet_info);
}

std::shared_lock rdlock(_meta_lock);
tablet_info->__set_tablet_id(_tablet_meta->tablet_id());
tablet_info->__set_schema_hash(_tablet_meta->schema_hash());
Expand All @@ -1546,9 +1553,7 @@ void Tablet::build_tablet_report_info(TTabletInfo* tablet_info) {
if (_tablet_meta->get_binlog_config() != nullptr) {
tablet_info->__set_binlog_config_version(_tablet_meta->get_binlog_config()->version);
}
if (_updates) {
_updates->get_tablet_info_extra(tablet_info);
} else {
if (_updates == nullptr) {
int64_t max_version = _timestamped_version_tracker.get_max_continuous_version();
auto max_rowset = rowset_with_max_version();
if (max_rowset != nullptr) {
Expand Down
41 changes: 24 additions & 17 deletions be/src/storage/tablet_manager.cpp
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Expand Up @@ -983,28 +983,35 @@ Status TabletManager::report_all_tablets_info(std::map<TTabletId, TTablet>* tabl

StarRocksMetrics::instance()->report_all_tablets_requests_total.increment(1);

size_t max_tablet_rowset_num = 0;
std::vector<TabletSharedPtr> all_tablets;
for (const auto& tablets_shard : _tablets_shards) {
std::shared_lock rlock(tablets_shard.lock);
for (const auto& [tablet_id, tablet_ptr] : tablets_shard.tablet_map) {
TTablet t_tablet;
TTabletInfo tablet_info;
tablet_ptr->build_tablet_report_info(&tablet_info);
max_tablet_rowset_num = std::max(max_tablet_rowset_num, tablet_ptr->version_count());
// find expired transaction corresponding to this tablet
TabletInfo tinfo(tablet_id, tablet_ptr->schema_hash(), tablet_ptr->tablet_uid());
auto find = expire_txn_map.find(tinfo);
if (find != expire_txn_map.end()) {
tablet_info.__set_transaction_ids(find->second);
expire_txn_map.erase(find);
}
t_tablet.tablet_infos.push_back(tablet_info);
for (const auto& [_, tablet_ptr] : tablets_shard.tablet_map) {
all_tablets.push_back(tablet_ptr);
}
}

if (!t_tablet.tablet_infos.empty()) {
tablets_info->emplace(tablet_id, t_tablet);
}
size_t max_tablet_rowset_num = 0;
for (auto& tablet_ptr : all_tablets) {
TTablet t_tablet;
TTabletInfo tablet_info;
tablet_ptr->build_tablet_report_info(&tablet_info);
max_tablet_rowset_num = std::max(max_tablet_rowset_num, tablet_ptr->version_count());
// find expired transaction corresponding to this tablet
TabletInfo tinfo(tablet_ptr->tablet_id(), tablet_ptr->schema_hash(), tablet_ptr->tablet_uid());
auto find = expire_txn_map.find(tinfo);
if (find != expire_txn_map.end()) {
tablet_info.__set_transaction_ids(find->second);
expire_txn_map.erase(find);
}
t_tablet.tablet_infos.push_back(tablet_info);

if (!t_tablet.tablet_infos.empty()) {
tablets_info->emplace(tablet_ptr->tablet_id(), t_tablet);
}
}
all_tablets.clear();

LOG(INFO) << "Report all " << tablets_info->size()
<< " tablets info. max_tablet_rowset_num:" << max_tablet_rowset_num;
StarRocksMetrics::instance()->max_tablet_rowset_num.set_value(max_tablet_rowset_num);
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The most risky bug in this code is:
Potential deadlock when accessing _tablets_shards.

You can modify the code like this:

std::vector<TabletSharedPtr> all_tablets;
for (const auto& tablets_shard : _tablets_shards) {
    // Ensure lock acquisition is done inside a smaller scope to prevent prolonged holding of locks
    {
        std::shared_lock rlock(tablets_shard.lock);
        for (const auto& [_, tablet_ptr] : tablets_shard.tablet_map) {
            all_tablets.push_back(tablet_ptr);
        }
    }
}

size_t max_tablet_rowset_num = 0;
for (auto& tablet_ptr : all_tablets) {
    TTablet t_tablet;
    TTabletInfo tablet_info;
    tablet_ptr->build_tablet_report_info(&tablet_info);
    max_tablet_rowset_num = std::max(max_tablet_rowset_num, tablet_ptr->version_count());
    // find expired transaction corresponding to this tablet
    TabletInfo tinfo(tablet_ptr->tablet_id(), tablet_ptr->schema_hash(), tablet_ptr->tablet_uid());
    auto find = expire_txn_map.find(tinfo);
    if (find != expire_txn_map.end()) {
        tablet_info.__set_transaction_ids(find->second);
        expire_txn_map.erase(find);
    }
    t_tablet.tablet_infos.push_back(tablet_info);

    if (!t_tablet.tablet_infos.empty()) {
        tablets_info->emplace(tablet_ptr->tablet_id(), t_tablet);
    }
}
all_tablets.clear();

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14 changes: 14 additions & 0 deletions be/test/storage/tablet_mgr_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -516,4 +516,18 @@ TEST_F(TabletMgrTest, RemoveTabletInDiskDisable) {
StorageEngine::instance()->tablet_manager()->drop_tablets_on_error_root_path(tablet_info_vec);
}

TEST_F(TabletMgrTest, GetTabletReportInfo) {
TTabletId tablet_id = 4251234666;
TSchemaHash schema_hash = 3929134666;
TCreateTabletReq create_tablet_req = get_create_tablet_request(tablet_id, schema_hash);
Status create_st = StorageEngine::instance()->create_tablet(create_tablet_req);
ASSERT_TRUE(create_st.ok());

TReportRequest request;
request.__isset.tablets = true;
Status st_report = StorageEngine::instance()->tablet_manager()->report_all_tablets_info(&request.tablets);
ASSERT_TRUE(st_report.ok());
ASSERT_TRUE(request.tablets.size() == 1);
}

} // namespace starrocks
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