query trigger semaphore unlimited waiting when high cpu

[XLPE]

Describe the bug or unexpected behaviour
Because many queries are in the pendding state for a long time, the limit of the maximum number of queries is triggered, the clickhouse server rejects subsequent requests.
After I traced the stack, it was because many query waited for the semaphore indefinitely, which resulted in the structure_lock read lock being never released. The next few hundred queries are all blocked waiting for the read lock.

Which ClickHouse server version to use
v18.14.13-stable

stacktrace
#0 pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1 0x000000000a3c7efc in std::condition_variable::wait(std::unique_lockstd::mutex&) ()
#2 0x0000000009c707b3 in std::condition_variable::wait<Poco::Semaphore::wait()::<lambda()>> (__p=..., __lock=..., this=0x7fa8afb7deb8) at /usr/include/c++/7/condition_variable:99
#3 Poco::Semaphore::wait (this=this@entry=0x7fa8afb7de88) at ../contrib/poco/Foundation/src/Semaphore.cpp:61
#4 0x00000000075fcbe6 in ConcurrentBoundedQueue<DB::(anonymous namespace)::OutputData<(DB::StreamUnionMode)0> >::pop (x=..., this=0x7fa8afb7de10)
at ../dbms/src/Common/ConcurrentBoundedQueue.h:82
#5 DB::UnionBlockInputStream<(DB::StreamUnionMode)0>::finalize (this=this@entry=0x7fa8afb7dc10) at ../dbms/src/DataStreams/UnionBlockInputStream.h:153
#6 0x00000000075fd5f8 in DB::UnionBlockInputStream<(DB::StreamUnionMode)0>::UnionBlockInputStream (this=0x7fa8afb7dc10, __in_chrg=) at ../dbms/src/DataStreams/UnionBlockInputStream.h:104
#7 0x00000000079d7c6c in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7fa8afb7dc00) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#8 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:684
#9 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::~__shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#10 std::shared_ptrDB::IBlockInputStream::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#11 std::_Destroy<std::shared_ptrDB::IBlockInputStream > (__pointer=) at /usr/include/c++/7/bits/stl_construct.h:98
#12 std::_Destroy_aux::__destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=0x7fa197a37850) at /usr/include/c++/7/bits/stl_construct.h:108
#13 std::_Destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=) at /usr/include/c++/7/bits/stl_construct.h:137
#14 std::_Destroy<std::shared_ptrDB::IBlockInputStream, std::shared_ptrDB::IBlockInputStream > (__last=0x7fa197a37860, __first=) at /usr/include/c++/7/bits/stl_construct.h:206
#15 std::vector<std::shared_ptrDB::IBlockInputStream, std::allocator<std::shared_ptrDB::IBlockInputStream > >::~vector (this=0x7fa957276e18, __in_chrg=) at /usr/include/c++/7/bits/stl_vector.h:434
#16 DB::IBlockInputStream::~IBlockInputStream (this=0x7fa957276e10, __in_chrg=) at ../dbms/src/DataStreams/IBlockInputStream.h:81
#17 DB::IProfilingBlockInputStream::IProfilingBlockInputStream (this=0x7fa957276e10, __in_chrg=) at ../dbms/src/DataStreams/IProfilingBlockInputStream.h:35
#18 DB::MergingAggregatedBlockInputStream::MergingAggregatedBlockInputStream (this=0x7fa957276e10, __in_chrg=) at ../dbms/src/DataStreams/MergingAggregatedBlockInputStream.h:14
#19 0x0000000007833cfa in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7fa957276e00) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#20 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:684
#21 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#22 std::shared_ptrDB::IBlockInputStream::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#23 std::_Destroy<std::shared_ptrDB::IBlockInputStream > (__pointer=) at /usr/include/c++/7/bits/stl_construct.h:98
#24 std::_Destroy_aux::__destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=0x7fa197a37860) at /usr/include/c++/7/bits/stl_construct.h:108
#25 std::_Destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=) at /usr/include/c++/7/bits/stl_construct.h:137
#26 std::_Destroy<std::shared_ptrDB::IBlockInputStream, std::shared_ptrDB::IBlockInputStream > (__last=0x7fa197a37870, __first=) at /usr/include/c++/7/bits/stl_construct.h:206
#27 std::vector<std::shared_ptrDB::IBlockInputStream, std::allocator<std::shared_ptrDB::IBlockInputStream > >::~vector (this=0x7f9ea46b2018, __in_chrg=) at /usr/include/c++/7/bits/stl_vector.h:434
#28 DB::IBlockInputStream::~IBlockInputStream (this=0x7f9ea46b2010, __in_chrg=) at ../dbms/src/DataStreams/IBlockInputStream.h:81
#29 DB::IProfilingBlockInputStream::IProfilingBlockInputStream (this=0x7f9ea46b2010, __in_chrg=) at ../dbms/src/DataStreams/IProfilingBlockInputStream.h:35
#30 DB::ExpressionBlockInputStream::ExpressionBlockInputStream (this=0x7f9ea46b2010, __in_chrg=) at ../dbms/src/DataStreams/ExpressionBlockInputStream.h:16
#31 0x0000000007833cfa in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7f9ea46b2000) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#32 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:684
#33 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#34 std::shared_ptrDB::IBlockInputStream::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#35 std::_Destroy<std::shared_ptrDB::IBlockInputStream > (__pointer=) at /usr/include/c++/7/bits/stl_construct.h:98
#36 std::_Destroy_aux::__destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=0x7fa197a37870) at /usr/include/c++/7/bits/stl_construct.h:108
#37 std::_Destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=) at /usr/include/c++/7/bits/stl_construct.h:137
#38 std::_Destroy<std::shared_ptrDB::IBlockInputStream, std::shared_ptrDB::IBlockInputStream > (__last=0x7fa197a37880, __first=)
at /usr/include/c++/7/bits/stl_construct.h:206
#39 std::vector<std::shared_ptrDB::IBlockInputStream, std::allocator<std::shared_ptrDB::IBlockInputStream > >::~vector (this=0x7f9ea46b2298, __in_chrg=)
at /usr/include/c++/7/bits/stl_vector.h:434
#40 DB::IBlockInputStream::~IBlockInputStream (this=0x7f9ea46b2290, __in_chrg=) at ../dbms/src/DataStreams/IBlockInputStream.h:81
#41 DB::IProfilingBlockInputStream::IProfilingBlockInputStream (this=0x7f9ea46b2290, __in_chrg=) at ../dbms/src/DataStreams/IProfilingBlockInputStream.h:35
#42 DB::ExpressionBlockInputStream::ExpressionBlockInputStream (this=0x7f9ea46b2290, __in_chrg=) at ../dbms/src/DataStreams/ExpressionBlockInputStream.h:16
#43 0x0000000007997b0a in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7f9ea46b2280) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#44 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:684
#45 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#46 std::shared_ptrDB::IBlockInputStream::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#47 std::_Destroy<std::shared_ptrDB::IBlockInputStream > (__pointer=) at /usr/include/c++/7/bits/stl_construct.h:98
#48 std::_Destroy_aux::__destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=0x7fa197a37890) at /usr/include/c++/7/bits/stl_construct.h:108
#49 std::_Destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=) at /usr/include/c++/7/bits/stl_construct.h:137
#50 std::_Destroy<std::shared_ptrDB::IBlockInputStream, std::shared_ptrDB::IBlockInputStream > (__last=0x7fa197a378a0, __first=)
at /usr/include/c++/7/bits/stl_construct.h:206
#51 std::vector<std::shared_ptrDB::IBlockInputStream, std::allocator<std::shared_ptrDB::IBlockInputStream > >::~vector (this=0x7f9ea46b2798, __in_chrg=)
at /usr/include/c++/7/bits/stl_vector.h:434
#52 DB::IBlockInputStream::~IBlockInputStream (this=0x7f9ea46b2790, __in_chrg=) at ../dbms/src/DataStreams/IBlockInputStream.h:81
#53 DB::IProfilingBlockInputStream::IProfilingBlockInputStream (this=0x7f9ea46b2790, __in_chrg=) at ../dbms/src/DataStreams/IProfilingBlockInputStream.h:35
#54 DB::ConvertingBlockInputStream::ConvertingBlockInputStream (this=0x7f9ea46b2790, __in_chrg=) at ../dbms/src/DataStreams/ConvertingBlockInputStream.h:23
#55 0x0000000007833cfa in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7f9ea46b2780) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#56 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:684
#57 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#58 std::shared_ptrDB::IBlockInputStream::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#59 std::_Destroy<std::shared_ptrDB::IBlockInputStream > (__pointer=) at /usr/include/c++/7/bits/stl_construct.h:98
#60 std::_Destroy_aux::__destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=0x7fa8ae861ec0) at /usr/include/c++/7/bits/stl_construct.h:108
#61 std::_Destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=) at /usr/include/c++/7/bits/stl_construct.h:137
#62 std::_Destroy<std::shared_ptrDB::IBlockInputStream, std::shared_ptrDB::IBlockInputStream > (__last=0x7fa8ae861ed0, __first=)
at /usr/include/c++/7/bits/stl_construct.h:206
#63 std::vector<std::shared_ptrDB::IBlockInputStream, std::allocator<std::shared_ptrDB::IBlockInputStream > >::~vector (this=0x7f9ea46b2c98, __in_chrg=)
at /usr/include/c++/7/bits/stl_vector.h:434
#64 DB::IBlockInputStream::~IBlockInputStream (this=0x7f9ea46b2c90, __in_chrg=) at ../dbms/src/DataStreams/IBlockInputStream.h:81
#65 DB::IProfilingBlockInputStream::IProfilingBlockInputStream (this=0x7f9ea46b2c90, __in_chrg=) at ../dbms/src/DataStreams/IProfilingBlockInputStream.h:35
#66 DB::ExpressionBlockInputStream::ExpressionBlockInputStream (this=0x7f9ea46b2c90, __in_chrg=) at ../dbms/src/DataStreams/ExpressionBlockInputStream.h:16
#67 0x0000000003087df2 in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7f9ea46b2c80) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#68 0x0000000003098182 in std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:684
#69 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#70 std::shared_ptrDB::IBlockInputStream::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#71 std::_Destroy<std::shared_ptrDB::IBlockInputStream > (__pointer=) at /usr/include/c++/7/bits/stl_construct.h:98
#72 std::_Destroy_aux::__destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=0x7fa8b09ad7d0) at /usr/include/c++/7/bits/stl_construct.h:108
#73 std::_Destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=) at /usr/include/c++/7/bits/stl_construct.h:137
#74 std::_Destroy<std::shared_ptrDB::IBlockInputStream, std::shared_ptrDB::IBlockInputStream > (__last=0x7fa8b09ad7e0, __first=)
at /usr/include/c++/7/bits/stl_construct.h:206
#75 std::vector<std::shared_ptrDB::IBlockInputStream, std::allocator<std::shared_ptrDB::IBlockInputStream > >::~vector (this=0x7fa95727c818, __in_chrg=)
at /usr/include/c++/7/bits/stl_vector.h:434
#76 DB::IBlockInputStream::~IBlockInputStream (this=0x7fa95727c810, __in_chrg=) at ../dbms/src/DataStreams/IBlockInputStream.h:81
#77 DB::IProfilingBlockInputStream::IProfilingBlockInputStream (this=0x7fa95727c810, __in_chrg=) at ../dbms/src/DataStreams/IProfilingBlockInputStream.h:35
#78 0x00000000079ee386 in DB::ParallelAggregatingBlockInputStream::ParallelAggregatingBlockInputStream (this=0x7fa95727c810, __in_chrg=)
at ../dbms/src/DataStreams/ParallelAggregatingBlockInputStream.h:19
#79 0x0000000007833cfa in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7fa95727c800) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#80 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:684
#81 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#82 std::shared_ptrDB::IBlockInputStream::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#83 std::_Destroy<std::shared_ptrDB::IBlockInputStream > (__pointer=) at /usr/include/c++/7/bits/stl_construct.h:98
#84 std::_Destroy_aux::__destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=0x7fa197a378c0) at /usr/include/c++/7/bits/stl_construct.h:108
#85 std::_Destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=) at /usr/include/c++/7/bits/stl_construct.h:137
#86 std::_Destroy<std::shared_ptrDB::IBlockInputStream, std::shared_ptrDB::IBlockInputStream > (__last=0x7fa197a378d0, __first=)
at /usr/include/c++/7/bits/stl_construct.h:206
#87 std::vector<std::shared_ptrDB::IBlockInputStream, std::allocator<std::shared_ptrDB::IBlockInputStream > >::~vector (this=0x7f9ea46b2f18, __in_chrg=)
at /usr/include/c++/7/bits/stl_vector.h:434
#88 DB::IBlockInputStream::~IBlockInputStream (this=0x7f9ea46b2f10, __in_chrg=) at ../dbms/src/DataStreams/IBlockInputStream.h:81
#89 DB::IProfilingBlockInputStream::IProfilingBlockInputStream (this=0x7f9ea46b2f10, __in_chrg=) at ../dbms/src/DataStreams/IProfilingBlockInputStream.h:35
#90 DB::ExpressionBlockInputStream::ExpressionBlockInputStream (this=0x7f9ea46b2f10, __in_chrg=) at ../dbms/src/DataStreams/ExpressionBlockInputStream.h:16
#91 0x0000000007833cfa in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7f9ea46b2f00) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#92 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:684
#93 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#94 std::shared_ptrDB::IBlockInputStream::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#95 std::_Destroy<std::shared_ptrDB::IBlockInputStream > (__pointer=) at /usr/include/c++/7/bits/stl_construct.h:98
#96 std::_Destroy_aux::__destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=0x7fa197a378e0) at /usr/include/c++/7/bits/stl_construct.h:108
#97 std::_Destroy<std::shared_ptrDB::IBlockInputStream> (__last=, __first=) at /usr/include/c++/7/bits/stl_construct.h:137
#98 std::_Destroy<std::shared_ptrDB::IBlockInputStream, std::shared_ptrDB::IBlockInputStream > (__last=0x7fa197a378f0, __first=)
at /usr/include/c++/7/bits/stl_construct.h:206
#99 std::vector<std::shared_ptrDB::IBlockInputStream, std::allocator<std::shared_ptrDB::IBlockInputStream > >::~vector (this=0x7f9ea46b3198, __in_chrg=)
at /usr/include/c++/7/bits/stl_vector.h:434
#100 DB::IBlockInputStream::~IBlockInputStream (this=0x7f9ea46b3190, __in_chrg=) at ../dbms/src/DataStreams/IBlockInputStream.h:81
#101 DB::IProfilingBlockInputStream::IProfilingBlockInputStream (this=0x7f9ea46b3190, __in_chrg=) at ../dbms/src/DataStreams/IProfilingBlockInputStream.h:35
#102 DB::ExpressionBlockInputStream::ExpressionBlockInputStream (this=0x7f9ea46b3190, __in_chrg=) at ../dbms/src/DataStreams/ExpressionBlockInputStream.h:16
#103 0x0000000003087df2 in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7f9ea46b3180) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#104 0x000000000761189c in std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:684
#105 std::__shared_ptr<DB::IBlockInputStream, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#106 std::shared_ptrDB::IBlockInputStream::shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#107 DB::QueryStatus::releaseQueryStreams (this=0x7fa8b0a48710) at ../dbms/src/Interpreters/ProcessList.cpp:309
#108 DB::ProcessListEntry::ProcessListEntry (this=0x7fac0e404970, __in_chrg=) at ../dbms/src/Interpreters/ProcessList.cpp:220
#109 0x0000000006acfc99 in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release (this=0x7fac0e404960) at /usr/include/c++/7/bits/shared_ptr_base.h:154
#110 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr_base.h:684
#111 std::__shared_ptr<DB::ProcessListEntry, (__gnu_cxx::_Lock_policy)2>::__shared_ptr (this=, __in_chrg=)
at /usr/include/c++/7/bits/shared_ptr_base.h:1123
#112 std::shared_ptrDB::ProcessListEntry::~shared_ptr (this=, __in_chrg=) at /usr/include/c++/7/bits/shared_ptr.h:93
#113 DB::BlockIO::~BlockIO (this=, __in_chrg=) at ../dbms/src/DataStreams/BlockIO.h:12
#114 0x0000000007692ae8 in DB::executeQuery(DB::ReadBuffer&, DB::WriteBuffer&, bool, DB::Context&, std::function<void (std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&)>) (istr=..., ostr=..., allow_into_outfile=allow_into_outfile@entry=false, context=..., set_content_type=...)
at ../dbms/src/Interpreters/executeQuery.cpp:448
#115 0x00000000030a2809 in DB::HTTPHandler::processQuery (this=this@entry=0x7fa8ae4e3920, request=..., params=..., response=..., used_output=...)
at ../dbms/programs/server/HTTPHandler.cpp:566
#116 0x00000000030a4e2e in DB::HTTPHandler::handleRequest (this=0x7fa8ae4e3920, request=..., response=...) at ../dbms/programs/server/HTTPHandler.cpp:675
#117 0x0000000009b703e2 in Poco::Net::HTTPServerConnection::run (this=0x7fa965f3b420) at ../contrib/poco/Net/src/HTTPServerConnection.cpp:85
#118 0x0000000009b68c8f in Poco::Net::TCPServerConnection::start (this=) at ../contrib/poco/Net/src/TCPServerConnection.cpp:43
#119 0x0000000009b6906a in Poco::Net::TCPServerDispatcher::run (this=0x7fac10fdb280) at ../contrib/poco/Net/src/TCPServerDispatcher.cpp:114
#120 0x0000000009c85e47 in Poco::PooledThread::run (this=0x7fa626ce7100) at ../contrib/poco/Foundation/src/ThreadPool.cpp:214
#121 0x0000000009c819b8 in Poco::ThreadImpl::runnableEntry (pThread=) at ../contrib/poco/Foundation/src/Thread_STD.cpp:139
#122 0x000000000a3db80f in execute_native_thread_routine ()
#123 0x00007fac11e296fa in start_thread (arg=0x7f542161b700) at pthread_create.c:333
#124 0x00007fac1144ab5d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

quesion:
1.unlimited waiting when poping queue. print size of output_queue is 0
https://github.com/ClickHouse/ClickHouse/blob/v18.14.13-stable/dbms/src/DataStreams/UnionBlockInputStream.h#L153