ClickHouse/docs/en/operations/system-tables/stack_trace.md

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/en/operations/system-tables/stack_trace

stack_trace

Contains stack traces of all server threads. Allows developers to introspect the server state.

To analyze stack frames, use the addressToLine, addressToLineWithInlines, addressToSymbol and demangle introspection functions.

Columns:

• thread_name (String) — Thread name.
• thread_id (UInt64) — Thread identifier.
• query_id (String) — Query identifier that can be used to get details about a query that was running from the query_log system table.
• trace (Array(UInt64)) — A stack trace which represents a list of physical addresses where the called methods are stored.

:::tip Check out the Knowledge Base for some handy queries, including how to see what threads are currently running and useful queries for troubleshooting. :::

Example

Enabling introspection functions:

SET allow_introspection_functions = 1;

Getting symbols from ClickHouse object files:

WITH arrayMap(x -> demangle(addressToSymbol(x)), trace) AS all SELECT thread_name, thread_id, query_id, arrayStringConcat(all, '\n') AS res FROM system.stack_trace LIMIT 1 \G;

Row 1:
──────
thread_name: QueryPipelineEx
thread_id:   743490
query_id:    dc55a564-febb-4e37-95bb-090ef182c6f1
res:         memcpy
large_ralloc
arena_ralloc
do_rallocx
Allocator<true, true>::realloc(void*, unsigned long, unsigned long, unsigned long)
HashTable<unsigned long, HashMapCell<unsigned long, char*, HashCRC32<unsigned long>, HashTableNoState, PairNoInit<unsigned long, char*>>, HashCRC32<unsigned long>, HashTableGrowerWithPrecalculation<8ul>, Allocator<true, true>>::resize(unsigned long, unsigned long)
void DB::Aggregator::executeImplBatch<false, false, true, DB::AggregationMethodOneNumber<unsigned long, HashMapTable<unsigned long, HashMapCell<unsigned long, char*, HashCRC32<unsigned long>, HashTableNoState, PairNoInit<unsigned long, char*>>, HashCRC32<unsigned long>, HashTableGrowerWithPrecalculation<8ul>, Allocator<true, true>>, true, false>>(DB::AggregationMethodOneNumber<unsigned long, HashMapTable<unsigned long, HashMapCell<unsigned long, char*, HashCRC32<unsigned long>, HashTableNoState, PairNoInit<unsigned long, char*>>, HashCRC32<unsigned long>, HashTableGrowerWithPrecalculation<8ul>, Allocator<true, true>>, true, false>&, DB::AggregationMethodOneNumber<unsigned long, HashMapTable<unsigned long, HashMapCell<unsigned long, char*, HashCRC32<unsigned long>, HashTableNoState, PairNoInit<unsigned long, char*>>, HashCRC32<unsigned long>, HashTableGrowerWithPrecalculation<8ul>, Allocator<true, true>>, true, false>::State&, DB::Arena*, unsigned long, unsigned long, DB::Aggregator::AggregateFunctionInstruction*, bool, char*) const
DB::Aggregator::executeImpl(DB::AggregatedDataVariants&, unsigned long, unsigned long, std::__1::vector<DB::IColumn const*, std::__1::allocator<DB::IColumn const*>>&, DB::Aggregator::AggregateFunctionInstruction*, bool, bool, char*) const
DB::Aggregator::executeOnBlock(std::__1::vector<COW<DB::IColumn>::immutable_ptr<DB::IColumn>, std::__1::allocator<COW<DB::IColumn>::immutable_ptr<DB::IColumn>>>, unsigned long, unsigned long, DB::AggregatedDataVariants&, std::__1::vector<DB::IColumn const*, std::__1::allocator<DB::IColumn const*>>&, std::__1::vector<std::__1::vector<DB::IColumn const*, std::__1::allocator<DB::IColumn const*>>, std::__1::allocator<std::__1::vector<DB::IColumn const*, std::__1::allocator<DB::IColumn const*>>>>&, bool&) const
DB::AggregatingTransform::work()
DB::ExecutionThreadContext::executeTask()
DB::PipelineExecutor::executeStepImpl(unsigned long, std::__1::atomic<bool>*)
void std::__1::__function::__policy_invoker<void ()>::__call_impl<std::__1::__function::__default_alloc_func<DB::PipelineExecutor::spawnThreads()::$_0, void ()>>(std::__1::__function::__policy_storage const*)
ThreadPoolImpl<ThreadFromGlobalPoolImpl<false>>::worker(std::__1::__list_iterator<ThreadFromGlobalPoolImpl<false>, void*>)
void std::__1::__function::__policy_invoker<void ()>::__call_impl<std::__1::__function::__default_alloc_func<ThreadFromGlobalPoolImpl<false>::ThreadFromGlobalPoolImpl<void ThreadPoolImpl<ThreadFromGlobalPoolImpl<false>>::scheduleImpl<void>(std::__1::function<void ()>, Priority, std::__1::optional<unsigned long>, bool)::'lambda0'()>(void&&)::'lambda'(), void ()>>(std::__1::__function::__policy_storage const*)
void* std::__1::__thread_proxy[abi:v15000]<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct>>, void ThreadPoolImpl<std::__1::thread>::scheduleImpl<void>(std::__1::function<void ()>, Priority, std::__1::optional<unsigned long>, bool)::'lambda0'()>>(void*)

Getting filenames and line numbers in ClickHouse source code:

WITH arrayMap(x -> addressToLine(x), trace) AS all, arrayFilter(x -> x LIKE '%/dbms/%', all) AS dbms SELECT thread_name, thread_id, query_id, arrayStringConcat(notEmpty(dbms) ? dbms : all, '\n') AS res FROM system.stack_trace LIMIT 1 \G;

Row 1:
──────
thread_name: clickhouse-serv

thread_id: 686
query_id:  cad353e7-1c29-4b2e-949f-93e597ab7a54
res:       /lib/x86_64-linux-gnu/libc-2.27.so
/build/obj-x86_64-linux-gnu/../src/Storages/System/StorageSystemStackTrace.cpp:182
/build/obj-x86_64-linux-gnu/../contrib/libcxx/include/vector:656
/build/obj-x86_64-linux-gnu/../src/Interpreters/InterpreterSelectQuery.cpp:1338
/build/obj-x86_64-linux-gnu/../src/Interpreters/InterpreterSelectQuery.cpp:751
/build/obj-x86_64-linux-gnu/../contrib/libcxx/include/optional:224
/build/obj-x86_64-linux-gnu/../src/Interpreters/InterpreterSelectWithUnionQuery.cpp:192
/build/obj-x86_64-linux-gnu/../src/Interpreters/executeQuery.cpp:384
/build/obj-x86_64-linux-gnu/../src/Interpreters/executeQuery.cpp:643
/build/obj-x86_64-linux-gnu/../src/Server/TCPHandler.cpp:251
/build/obj-x86_64-linux-gnu/../src/Server/TCPHandler.cpp:1197
/build/obj-x86_64-linux-gnu/../contrib/poco/Net/src/TCPServerConnection.cpp:57
/build/obj-x86_64-linux-gnu/../contrib/libcxx/include/atomic:856
/build/obj-x86_64-linux-gnu/../contrib/poco/Foundation/include/Poco/Mutex_POSIX.h:59
/build/obj-x86_64-linux-gnu/../contrib/poco/Foundation/include/Poco/AutoPtr.h:223
/lib/x86_64-linux-gnu/libpthread-2.27.so
/lib/x86_64-linux-gnu/libc-2.27.so

See Also

• Introspection Functions — Which introspection functions are available and how to use them.
• system.trace_log — Contains stack traces collected by the sampling query profiler.
• arrayMap — Description and usage example of the arrayMap function.
• arrayFilter — Description and usage example of the arrayFilter function.