mirror of
https://github.com/ClickHouse/ClickHouse.git
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99 lines
5.5 KiB
Markdown
99 lines
5.5 KiB
Markdown
---
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slug: /en/operations/system-tables/stack_trace
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---
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# stack_trace
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Contains stack traces of all server threads. Allows developers to introspect the server state.
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To analyze stack frames, use the `addressToLine`, `addressToLineWithInlines`, `addressToSymbol` and `demangle` [introspection functions](../../sql-reference/functions/introspection.md).
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Columns:
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- `thread_name` ([String](../../sql-reference/data-types/string.md)) — Thread name.
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- `thread_id` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Thread identifier.
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- `query_id` ([String](../../sql-reference/data-types/string.md)) — Query identifier that can be used to get details about a query that was running from the [query_log](../system-tables/query_log.md) system table.
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- `trace` ([Array(UInt64)](../../sql-reference/data-types/array.md)) — A [stack trace](https://en.wikipedia.org/wiki/Stack_trace) which represents a list of physical addresses where the called methods are stored.
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:::tip
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Check out the Knowledge Base for some handy queries, including [how to see what threads are currently running](https://clickhouse.com/docs/knowledgebase/find-expensive-queries) and [useful queries for troubleshooting](https://clickhouse.com/docs/knowledgebase/useful-queries-for-troubleshooting).
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:::
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**Example**
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Enabling introspection functions:
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``` sql
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SET allow_introspection_functions = 1;
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```
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Getting symbols from ClickHouse object files:
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``` sql
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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;
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```
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``` text
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Row 1:
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──────
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thread_name: clickhouse-serv
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thread_id: 686
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query_id: 1a11f70b-626d-47c1-b948-f9c7b206395d
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res: sigqueue
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DB::StorageSystemStackTrace::fillData(std::__1::vector<COW<DB::IColumn>::mutable_ptr<DB::IColumn>, std::__1::allocator<COW<DB::IColumn>::mutable_ptr<DB::IColumn> > >&, DB::Context const&, DB::SelectQueryInfo const&) const
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DB::IStorageSystemOneBlock<DB::StorageSystemStackTrace>::read(std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, DB::SelectQueryInfo const&, DB::Context const&, DB::QueryProcessingStage::Enum, unsigned long, unsigned int)
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DB::InterpreterSelectQuery::executeFetchColumns(DB::QueryProcessingStage::Enum, DB::QueryPipeline&, std::__1::shared_ptr<DB::PrewhereInfo> const&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&)
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DB::InterpreterSelectQuery::executeImpl(DB::QueryPipeline&, std::__1::shared_ptr<DB::IBlockInputStream> const&, std::__1::optional<DB::Pipe>)
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DB::InterpreterSelectQuery::execute()
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DB::InterpreterSelectWithUnionQuery::execute()
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DB::executeQueryImpl(char const*, char const*, DB::Context&, bool, DB::QueryProcessingStage::Enum, bool, DB::ReadBuffer*)
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DB::executeQuery(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, DB::Context&, bool, DB::QueryProcessingStage::Enum, bool)
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DB::TCPHandler::runImpl()
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DB::TCPHandler::run()
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Poco::Net::TCPServerConnection::start()
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Poco::Net::TCPServerDispatcher::run()
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Poco::PooledThread::run()
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Poco::ThreadImpl::runnableEntry(void*)
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start_thread
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__clone
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```
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Getting filenames and line numbers in ClickHouse source code:
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``` sql
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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;
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```
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``` text
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Row 1:
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──────
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thread_name: clickhouse-serv
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thread_id: 686
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query_id: cad353e7-1c29-4b2e-949f-93e597ab7a54
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res: /lib/x86_64-linux-gnu/libc-2.27.so
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/build/obj-x86_64-linux-gnu/../src/Storages/System/StorageSystemStackTrace.cpp:182
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/build/obj-x86_64-linux-gnu/../contrib/libcxx/include/vector:656
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/build/obj-x86_64-linux-gnu/../src/Interpreters/InterpreterSelectQuery.cpp:1338
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/build/obj-x86_64-linux-gnu/../src/Interpreters/InterpreterSelectQuery.cpp:751
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/build/obj-x86_64-linux-gnu/../contrib/libcxx/include/optional:224
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/build/obj-x86_64-linux-gnu/../src/Interpreters/InterpreterSelectWithUnionQuery.cpp:192
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/build/obj-x86_64-linux-gnu/../src/Interpreters/executeQuery.cpp:384
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/build/obj-x86_64-linux-gnu/../src/Interpreters/executeQuery.cpp:643
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/build/obj-x86_64-linux-gnu/../src/Server/TCPHandler.cpp:251
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/build/obj-x86_64-linux-gnu/../src/Server/TCPHandler.cpp:1197
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/build/obj-x86_64-linux-gnu/../contrib/poco/Net/src/TCPServerConnection.cpp:57
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/build/obj-x86_64-linux-gnu/../contrib/libcxx/include/atomic:856
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/build/obj-x86_64-linux-gnu/../contrib/poco/Foundation/include/Poco/Mutex_POSIX.h:59
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/build/obj-x86_64-linux-gnu/../contrib/poco/Foundation/include/Poco/AutoPtr.h:223
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/lib/x86_64-linux-gnu/libpthread-2.27.so
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/lib/x86_64-linux-gnu/libc-2.27.so
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```
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**See Also**
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- [Introspection Functions](../../sql-reference/functions/introspection.md) — Which introspection functions are available and how to use them.
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- [system.trace_log](../system-tables/trace_log.md) — Contains stack traces collected by the sampling query profiler.
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- [arrayMap](../../sql-reference/functions/array-functions.md#array-map) — Description and usage example of the `arrayMap` function.
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- [arrayFilter](../../sql-reference/functions/array-functions.md#array-filter) — Description and usage example of the `arrayFilter` function.
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