서버에서 현재 실행 중인 코드를 확인하는 방법

ClickHouse는 system.stack_trace와 같은 내부 검사 도구를 제공하여 각 서버 스레드에서 현재 어떤 코드가 실행 중인지 확인할 수 있으며, 디버깅과 성능 모니터링에 도움이 됩니다.

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서버에서 현재 실행 중인 코드 확인

ClickHouse는 내장 디버거와 내부 검사 기능을 제공합니다.

예를 들어, system.stack_trace 테이블을 쿼리하면 런타임 중에 각 서버 스레드의 스택 트레이스를 가져올 수 있습니다:

SELECT
    count(),
    arrayStringConcat(arrayMap(x -> concat(demangle(addressToSymbol(x)), '\n    ', addressToLine(x)), trace), '\n') AS sym
FROM system.stack_trace
GROUP BY trace
ORDER BY count() DESC
LIMIT 10
FORMAT Vertical
SETTINGS allow_introspection_functions = 1;

쿼리 결과에는 스레드가 실행 중이거나 대기 중인 ClickHouse 소스 코드 위치가 표시됩니다. (인트로스펙션 함수를 사용하려면 allow_introspection_functions를 1로 설정해야 합니다.) 응답은 다음과 같습니다:

Row 1:
──────
count(): 144
sym:     pthread_cond_wait

DB::BackgroundSchedulePool::threadFunction()
    /usr/bin/clickhouse

    /usr/bin/clickhouse
ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>)
    /usr/bin/clickhouse

    /usr/bin/clickhouse

clone

Row 2:
──────
count(): 80
sym:     pthread_cond_wait

std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&)
    /usr/bin/clickhouse
DB::MergeTreeBackgroundExecutor<DB::OrdinaryRuntimeQueue>::threadFunction()
    /usr/bin/clickhouse
ThreadPoolImpl<ThreadFromGlobalPoolImpl<false>>::worker(std::__1::__list_iterator<ThreadFromGlobalPoolImpl<false>, void*>)
    /usr/bin/clickhouse
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 ()>, long, std::__1::optional<unsigned long>, bool)::'lambda0'()>(void&&)::'lambda'(), void ()>>(std::__1::__function::__policy_storage const*)
    /usr/bin/clickhouse
ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>)
    /usr/bin/clickhouse

    /usr/bin/clickhouse

clone

Row 3:
──────
count(): 55
sym:     pthread_cond_wait

ThreadPoolImpl<ThreadFromGlobalPoolImpl<false>>::worker(std::__1::__list_iterator<ThreadFromGlobalPoolImpl<false>, void*>)
    /usr/bin/clickhouse
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 ()>, long, std::__1::optional<unsigned long>, bool)::'lambda0'()>(void&&)::'lambda'(), void ()>>(std::__1::__function::__policy_storage const*)
    /usr/bin/clickhouse
ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>)
    /usr/bin/clickhouse

    /usr/bin/clickhouse

clone

Row 4:
──────
count(): 16
sym:

DB::AsynchronousInsertQueue::processBatchDeadlines(unsigned long)
    /usr/bin/clickhouse

    /usr/bin/clickhouse
ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>)
    /usr/bin/clickhouse

    /usr/bin/clickhouse

clone

Row 5:
──────
count(): 16
sym:     pthread_cond_wait

std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&)
    /usr/bin/clickhouse
DB::MergeTreeBackgroundExecutor<DB::MergeMutateRuntimeQueue>::threadFunction()
    /usr/bin/clickhouse
ThreadPoolImpl<ThreadFromGlobalPoolImpl<false>>::worker(std::__1::__list_iterator<ThreadFromGlobalPoolImpl<false>, void*>)
    /usr/bin/clickhouse
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 ()>, long, std::__1::optional<unsigned long>, bool)::'lambda0'()>(void&&)::'lambda'(), void ()>>(std::__1::__function::__policy_storage const*)
    /usr/bin/clickhouse
ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>)
    /usr/bin/clickhouse

    /usr/bin/clickhouse

clone

Row 6:
──────
count(): 10
sym:     poll

Poco::Net::SocketImpl::pollImpl(Poco::Timespan&, int)
    /usr/bin/clickhouse
Poco::Net::SocketImpl::poll(Poco::Timespan const&, int)
    /usr/bin/clickhouse
Poco::Net::TCPServer::run()
    /usr/bin/clickhouse
Poco::ThreadImpl::runnableEntry(void*)
    /usr/bin/clickhouse

clone

Row 7:
──────
count(): 9
sym:     pthread_cond_wait

ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>)
    /usr/bin/clickhouse

    /usr/bin/clickhouse

clone

Row 8:
──────
count(): 7
sym:     poll

Poco::Net::SocketImpl::pollImpl(Poco::Timespan&, int)
    /usr/bin/clickhouse
Poco::Net::SocketImpl::poll(Poco::Timespan const&, int)
    /usr/bin/clickhouse
DB::ReadBufferFromPocoSocket::poll(unsigned long) const
    /usr/bin/clickhouse
DB::TCPHandler::runImpl()
    /usr/bin/clickhouse
DB::TCPHandler::run()
    /usr/bin/clickhouse

    /usr/bin/clickhouse
Poco::Net::TCPServerConnection::start()
    /usr/bin/clickhouse
Poco::Net::TCPServerDispatcher::run()
    /usr/bin/clickhouse
Poco::PooledThread::run()
    /usr/bin/clickhouse
Poco::ThreadImpl::runnableEntry(void*)
    /usr/bin/clickhouse

clone

Row 9:
───────
count(): 3
sym:     pthread_cond_wait

Poco::EventImpl::waitImpl()
    /usr/bin/clickhouse
DB::DDLWorker::runCleanupThread()
    /usr/bin/clickhouse
void std::__1::__function::__policy_invoker<void ()>::__call_impl<std::__1::__function::__default_alloc_func<ThreadFromGlobalPoolImpl<true>::ThreadFromGlobalPoolImpl<void (DB::DDLWorker::*)(), DB::DDLWorker*>(void (DB::DDLWorker::*&&)(), DB::DDLWorker*&&)::'lambda'(), void ()>>(std::__1::__function::__policy_storage const*)
    /usr/bin/clickhouse
ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>)
    /usr/bin/clickhouse

    /usr/bin/clickhouse

clone

Row 10:
───────
count(): 3
sym:     pthread_cond_wait

Poco::EventImpl::waitImpl()
    /usr/bin/clickhouse
DB::DDLWorker::runMainThread()
    /usr/bin/clickhouse
void std::__1::__function::__policy_invoker<void ()>::__call_impl<std::__1::__function::__default_alloc_func<ThreadFromGlobalPoolImpl<true>::ThreadFromGlobalPoolImpl<void (DB::DDLWorker::*)(), DB::DDLWorker*>(void (DB::DDLWorker::*&&)(), DB::DDLWorker*&&)::'lambda'(), void ()>>(std::__1::__function::__policy_storage const*)
    /usr/bin/clickhouse
ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>)
    /usr/bin/clickhouse

    /usr/bin/clickhouse

clone

10 rows in set. Elapsed: 0.026 sec.

.deb/.rpm/.tgz로 ClickHouse를 설치한 경우, 소스 코드의 줄 번호를 확인할 수 있도록 디버그 정보가 포함된 패키지를 추가로 설치할 수도 있습니다:

sudo apt install clickhouse-common-static-dbg

ClickHouse를 단일 바이너리로 설치했다면 디버그 정보가 이미 포함되어 있습니다.

좀 더 상위 수준의 정보를 보려면 다음 system table도 확인해 보십시오:

• system.processes
• system.query_log
• system.metric_log
• system.asynchronous_metric_log
• system.trace_log
• system.processor_profile_log

그 밖의 system table에도 유용한 정보가 있습니다.