(gdb) bt full
#0  0x00007f423fde03d7 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:55
        resultvar = 0
        pid = 9361
        selftid = 9378
#1  0x00007f423fde1ac8 in __GI_abort () at abort.c:90
        save_stage = 2
        act = {__sigaction_handler = {sa_handler = 0x0, sa_sigaction = 0x0}, sa_mask = {__val = {0 <repeats 13 times>, 139922293837825, 139922516369411, 139922519826880}}, sa_flags = 1081302032, sa_restorer = 0x107f190 <stderr>}
        sigs = {__val = {32, 0 <repeats 15 times>}}
#2  0x00007f424072b63c in __gnu_cxx::__verbose_terminate_handler() [clone .cold] () from /opt/couchbase/bin/../lib/libstdc++.so.6
No symbol table info available.
#3  0x0000000000b374ab in backtrace_terminate_handler() () at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/utilities/terminate_handler.cc:88
No locals.
#4  0x00007f42407368f6 in __cxxabiv1::__terminate(void (*)()) () from /opt/couchbase/bin/../lib/libstdc++.so.6
No symbol table info available.
#5  0x00007f4240736961 in std::terminate() () from /opt/couchbase/bin/../lib/libstdc++.so.6
No symbol table info available.
#6  0x00007f4240736bf4 in __cxa_throw () from /opt/couchbase/bin/../lib/libstdc++.so.6
No symbol table info available.
#7  0x0000000000539ad4 in cb::throwWithTrace<std::underflow_error> (exception=...) at /home/couchbase/jenkins/workspace/couchbase-server-unix/server_build/tlm/deps/boost.exploded/include/boost/exception/info.hpp:129
No locals.
#8  0x0000000000832c08 in cb::ThrowExceptionUnderflowPolicy<unsigned long>::underflow () at /opt/gcc-10.2.0/include/c++/10.2.0/bits/char_traits.h:322
No locals.
#9  0x000000000083308f in store (desired=18446744073709551473, this=0x7f41cca15960) at /opt/gcc-10.2.0/include/c++/10.2.0/bits/atomic_base.h:116
No locals.
#10 operator= (val=18446744073709551473, this=0x7f41cca15960) at /home/couchbase/jenkins/workspace/couchbase-server-unix/platform/include/platform/non_negative_counter.h:360
No locals.
#11 setNumTotalItems (totalItems=18446744073709551473, this=0x7f41cca15500) at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/engines/ep/src/ep_vb.cc:423
No locals.
#12 EPVBucket::setNumTotalItems(KVStoreIface&) () at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/engines/ep/src/ep_vb.cc:1179
        vbItemCount = <optimized out>
        vbState = <optimized out>
#13 0x00000000007442f1 in Warmup::estimateDatabaseItemCount (this=0x7f41cd853a00, shardId=<optimized out>) at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/engines/ep/src/kvshard.h:72
        epVb = @0x7f41cca15500: <error reading variable>
        vbItemCount = 0
        itr = {<folly::detail::IteratorFacade<folly::AtomicHashMap<unsigned short, std::shared_ptr<VBucket> >::ahm_iterator<folly::AtomicHashMap<unsigned short, std::shared_ptr<VBucket>, std::hash<unsigned short>, std::equal_to<unsigned short>, std::allocator<char>, folly::AtomicHashArrayLinearProbeFcn, folly::identity_fn>, std::pair<unsigned short const, std::shared_ptr<VBucket> >, folly::AtomicHashArray<unsigned short, std::shared_ptr<VBucket>, std::hash<unsigned short>, std::equal_to<unsigned short>, std::allocator<char>, folly::AtomicHashArrayLinearProbeFcn, folly::identity_fn>::aha_iterator<folly::AtomicHashArray<unsigned short, std::shared_ptr<VBucket>, std::hash<unsigned short>, std::equal_to<unsigned short>, std::allocator<char>, folly::AtomicHashArrayLinearProbeFcn, folly::identity_fn>, std::pair<unsigned short const, std::shared_ptr<VBucket> > > >, std::pair<unsigned short const, std::shared_ptr<VBucket> >, std::forward_iterator_tag>> = {<No data fields>}, ahm_ = 0x7f41cd853bd8, 
          subMap_ = <optimized out>, 
          subIt_ = {<folly::detail::IteratorFacade<folly::AtomicHashArray<unsigned short, std::shared_ptr<VBucket>, std::hash<unsigned short>, std::equal_to<unsigned short>, std::allocator<char>, folly::AtomicHashArrayLinearProbeFcn, folly::identity_fn>::aha_iterator<folly::AtomicHashArray<unsigned short, std::shared_ptr<VBucket>, std::hash<unsigned short>, std::equal_to<unsigned short>, std::allocator<char>, folly::AtomicHashArrayLinearProbeFcn, folly::identity_fn>, std::pair<unsigned short const, std::shared_ptr<VBucket> > >, std::pair<unsigned short const, std::shared_ptr<VBucket> >, std::forward_iterator_tag>> = {<No data fields>}, aha_ = <optimized out>, offset_ = <optimized out>}}
        vbid = <optimized out>
        __for_range = <optimized out>
        item_count = 1361
#14 0x000000000074e251 in WarmupEstimateDatabaseItemCount::run (this=0x7f41dbfe6190) at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/engines/ep/src/warmup.cc:266
        phosphor_internal_category_enabled_265 = {_M_b = {_M_p = 0x0}, static is_always_lock_free = <optimized out>}
        phosphor_internal_category_enabled_temp_265 = <optimized out>
        phosphor_internal_tpi_265 = {category = 0x0, name = 0x0, type = phosphor::AsyncStart, argument_names = {_M_elems = {0x0, 0x0}}, argument_types = {_M_elems = {phosphor::is_bool, phosphor::is_bool}}}
        phosphor_internal_guard_265 = {tpi = 0x1067d80 <WarmupEstimateDatabaseItemCount::run()::phosphor_internal_tpi_265>, enabled = true, arg1 = {<No data fields>}, arg2 = {<No data fields>}, start = {__d = {__r = 25020111640450171}}}
#15 0x0000000000aaa622 in GlobalTask::execute() () at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/executor/globaltask.cc:68
        guard = {previous = 0x0}
#16 0x0000000000aa7725 in FollyExecutorPool::TaskProxy::scheduleViaCPUPool()::{lambda()#2}::operator()() const (__closure=0x7f42329ed840) at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/executor/folly_executorpool.cc:189
        scheduleOverhead = <optimized out>
        start = {__d = {__r = 25020111640444601}}
        runAgain = false
        proxy = @0x7f423ab2c1c0: <error reading variable>
#17 0x0000000000bfbbd0 in operator() (this=0x7f42329ed840) at /home/couchbase/jenkins/workspace/cbdeps-platform-build-old/deps/packages/build/folly/folly-prefix/src/folly/folly/Function.h:416
        fn = @0x7f42329ed840: {<folly::detail::function::FunctionTraits<void()>> = {<No data fields>}, data_ = {big = 0x7f423ab2c1c0, tiny = {
              __data = "\300\301\262:B\177\000\000\000\000\000\000\000\000\000\000P\203\267>B\177\000\000\242$\000\000\000\000\000\000(\000\000\000\000\000\000\000\020\331\236\062B\177\000", __align = {<No data fields>}}}, 
          call_ = 0xaa7de0 <folly::detail::function::FunctionTraits<void ()>::callSmall<FollyExecutorPool::TaskProxy::scheduleViaCPUPool()::{lambda()#2}>(folly::detail::function::Data&)>, 
          exec_ = 0xaa6530 <folly::detail::function::execSmall<FollyExecutorPool::TaskProxy::scheduleViaCPUPool()::{lambda()#2}>(folly::detail::function::Op, folly::detail::function::Data*, folly::detail::function::Data)>}
#18 folly::ThreadPoolExecutor::runTask(std::shared_ptr<folly::ThreadPoolExecutor::Thread> const&, folly::ThreadPoolExecutor::Task&&) (this=this@entry=0x7f423eafe400, thread=..., 
    task=task@entry=<unknown type in /usr/lib/debug/opt/couchbase/bin/memcached-7.1.0-2111.x86_64.debug, CU 0xa3160b8, DIE 0xa399fed>)
    at /home/couchbase/jenkins/workspace/cbdeps-platform-build-old/deps/packages/build/folly/folly-prefix/src/folly/folly/executors/ThreadPoolExecutor.cpp:97
        rctx = {prev_ = {<std::__shared_ptr<folly::RequestContext, (__gnu_cxx::_Lock_policy)2>> = {<std::__shared_ptr_access<folly::RequestContext, (__gnu_cxx::_Lock_policy)2, false, false>> = {<No data fields>}, _M_ptr = 0x0, _M_refcount = {
---Type <return> to continue, or q <return> to quit---
                _M_pi = 0x0}}, <No data fields>}}
        startTime = {__d = {__r = 25020111640437092}}
        stats = {expired = false, waitTime = {__r = 61746}, runTime = {__r = 0}, enqueueTime = {__d = {__r = 25020111640375346}}, requestId = 0}
#19 0x0000000000be650a in folly::CPUThreadPoolExecutor::threadRun (this=0x7f423eafe400, thread=...)
    at /home/couchbase/jenkins/workspace/cbdeps-platform-build-old/deps/packages/build/folly/folly-prefix/src/folly/folly/executors/CPUThreadPoolExecutor.cpp:265
        task = {storage_ = {{emptyState = -64 '\300', value = {<folly::ThreadPoolExecutor::Task> = {func_ = {<folly::detail::function::FunctionTraits<void()>> = {<No data fields>}, data_ = {big = 0x7f423ab2c1c0, tiny = {
                        __data = "\300\301\262:B\177\000\000\000\000\000\000\000\000\000\000P\203\267>B\177\000\000\242$\000\000\000\000\000\000(\000\000\000\000\000\000\000\020\331\236\062B\177\000", __align = {<No data fields>}}}, 
                    call_ = 0xaa7de0 <folly::detail::function::FunctionTraits<void ()>::callSmall<FollyExecutorPool::TaskProxy::scheduleViaCPUPool()::{lambda()#2}>(folly::detail::function::Data&)>, 
                    exec_ = 0xaa6530 <folly::detail::function::execSmall<FollyExecutorPool::TaskProxy::scheduleViaCPUPool()::{lambda()#2}>(folly::detail::function::Op, folly::detail::function::Data*, folly::detail::function::Data)>}, enqueueTime_ = {
                    __d = {__r = 25020111640375346}}, expiration_ = {__r = 0}, expireCallback_ = {<folly::detail::function::FunctionTraits<void()>> = {<No data fields>}, data_ = {big = 0x24a2, tiny = {
                        __data = "\242$\000\000\000\000\000\000\vq\243", '\000' <repeats 13 times>, "_\216\231BB\177\000\000pj\036:B\177\000\000@&\272BB\177\000", __align = {<No data fields>}}}, call_ = 0x4662f9
     <folly::detail::function::FunctionTraits<void ()>::uninitCall(folly::detail::function::Data&)>, exec_ = 0x0}, 
                  context_ = {<std::__shared_ptr<folly::RequestContext, (__gnu_cxx::_Lock_policy)2>> = {<std::__shared_ptr_access<folly::RequestContext, (__gnu_cxx::_Lock_policy)2, false, false>> = {<No data fields>}, _M_ptr = 0x0, _M_refcount = {
                        _M_pi = 0x0}}, <No data fields>}}, poison = false, priority_ = 0 '\000', queueObserverPayload_ = 0}}, hasValue = true}}
        guard = {list_ = {forbid = true, prev = 0x0, curr = {name = {static npos = <optimized out>, b_ = 0xccd46b "CPUThreadPoolExecutor", e_ = 0xccd480 ""}}}}
#20 0x0000000000bfeb89 in __invoke_impl<void, void (folly::ThreadPoolExecutor::*&)(std::shared_ptr<folly::ThreadPoolExecutor::Thread>), folly::ThreadPoolExecutor*&, std::shared_ptr<folly::ThreadPoolExecutor::Thread>&> (__t=<optimized out>, 
    __f=<optimized out>) at /usr/local/include/c++/7.3.0/bits/invoke.h:73
No locals.
#21 __invoke<void (folly::ThreadPoolExecutor::*&)(std::shared_ptr<folly::ThreadPoolExecutor::Thread>), folly::ThreadPoolExecutor*&, std::shared_ptr<folly::ThreadPoolExecutor::Thread>&> (__fn=<optimized out>)
    at /usr/local/include/c++/7.3.0/bits/invoke.h:95
No locals.
#22 __call<void, 0, 1> (__args=<optimized out>, this=<optimized out>) at /usr/local/include/c++/7.3.0/functional:467
No locals.
#23 operator()<> (this=<optimized out>) at /usr/local/include/c++/7.3.0/functional:551
No locals.
#24 folly::detail::function::FunctionTraits<void ()>::callBig<std::_Bind<void (folly::ThreadPoolExecutor::*(folly::ThreadPoolExecutor*, std::shared_ptr<folly::ThreadPoolExecutor::Thread>))(std::shared_ptr<folly::ThreadPoolExecutor::Thread>)> >(folly::detail::function::Data&) (p=...) at /home/couchbase/jenkins/workspace/cbdeps-platform-build-old/deps/packages/build/folly/folly-prefix/src/folly/folly/Function.h:401
        fn = <optimized out>
#25 0x0000000000aa73b4 in operator() (this=0x7f423eabfac0) at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/executor/folly_executorpool.cc:47
        fn = @0x7f423eabfac0: <error reading variable>
#26 operator() (__closure=0x7f423eabfac0) at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/executor/folly_executorpool.cc:47
        threadNameOpt = {storage_ = {{emptyState = -96 '\240', value = {static npos = 18446744073709551615, _M_dataplus = {<std::allocator<char>> = {<__gnu_cxx::new_allocator<char>> = {<No data fields>}, <No data fields>}, 
                  _M_p = 0x7f42329ed9a0 "ReaderPool0"}, _M_string_length = 11, {_M_local_buf = "ReaderPool0\000\000\000\000", _M_allocated_capacity = 8021036716148221266}}}, hasValue = true}}
        func = <error reading variable func (Cannot access memory at address 0x7f423eabfac0)>
#27 folly::detail::function::FunctionTraits<void ()>::callBig<CBRegisteredThreadFactory::newThread(folly::Function<void ()>&&)::{lambda()#1}>(folly::detail::function::Data&) (p=...)
    at /home/couchbase/jenkins/workspace/couchbase-server-unix/server_build/tlm/deps/folly.exploded/include/folly/Function.h:401
        fn = @0x7f423eabfac0: <error reading variable>
#28 0x00007f424075fd40 in execute_native_thread_routine () from /opt/couchbase/bin/../lib/libstdc++.so.6
No symbol table info available.
#29 0x00007f4242567ea5 in start_thread (arg=0x7f42329ff700) at pthread_create.c:307
        __res = <optimized out>
        pd = 0x7f42329ff700
        now = <optimized out>
        unwind_buf = {cancel_jmp_buf = {{jmp_buf = {139922293913344, -4475168323465470195, 0, 8392704, 0, 139922293913344, 4567044899257622285, 4567079597083500301}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x0, 0x0}, data = {prev = 0x0, 
              cleanup = 0x0, canceltype = 0}}}
        not_first_call = <optimized out>
        pagesize_m1 = <optimized out>
        sp = <optimized out>
        freesize = <optimized out>
#30 0x00007f423fea89fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
No locals.
(gdb)