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https://issues.apache.org/jira/browse/KUDU-2727?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17126243#comment-17126243
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Alexey Serbin commented on KUDU-2727:
-------------------------------------
One more set of stack traces:
{noformat}
tids=[1324418]
0x7f61b79fc5e0 <unknown>
0x1ec35f4 base::internal::SpinLockDelay()
0x1ec347c base::SpinLock::SlowLock()
0xb4236d kudu::consensus::Peer::SendNextRequest()
0xb43771
_ZN5boost6detail8function26void_function_obj_invoker0IZN4kudu9consensus4Peer13SignalRequestEbEUlvE_vE6invokeERNS1_15function_bufferE
0x1eb1d1d kudu::FunctionRunnable::Run()
0x1eaedbf kudu::ThreadPool::DispatchThread()
0x1ea4a84 kudu::Thread::SuperviseThread()
0x7f61b79f4e25 start_thread
0x7f61b5cd234d __clone
tids=[93293,93284,93285,93286,93287,93288,93289,93290,93291,93292,93304,93294,93295,93296,93297,93298,93299,93300,93301,93302,93303,93313,93322,93321,93320,93319,93318,93317,93316,93315,93314,93283,93312,93311,93310,93309,93308,93307,93306,93305]
0x7f61b79fc5e0 <unknown>
0x1ec35f4 base::internal::SpinLockDelay()
0x1ec347c base::SpinLock::SlowLock()
0xb7deb8
kudu::consensus::RaftConsensus::CheckLeadershipAndBindTerm()
0xaab010 kudu::tablet::TransactionDriver::ExecuteAsync()
0xaa344c kudu::tablet::TabletReplica::SubmitWrite()
0x928fb0 kudu::tserver::TabletServiceImpl::Write()
0x1d2e8d9 kudu::rpc::GeneratedServiceIf::Handle()
0x1d2efd9 kudu::rpc::ServicePool::RunThread()
0x1ea4a84 kudu::Thread::SuperviseThread()
0x7f61b79f4e25 start_thread
0x7f61b5cd234d __clone
tids=[1324661]
0x7f61b79fc5e0 <unknown>
0x1ec35f4 base::internal::SpinLockDelay()
0x1ec347c base::SpinLock::SlowLock()
0xb7df8e kudu::consensus::RaftConsensus::Replicate()
0xaab8e7 kudu::tablet::TransactionDriver::Prepare()
0xaac009 kudu::tablet::TransactionDriver::PrepareTask()
0x1eaedbf kudu::ThreadPool::DispatchThread()
0x1ea4a84 kudu::Thread::SuperviseThread()
0x7f61b79f4e25 start_thread
0x7f61b5cd234d __clone
tids=[93383]
0x7f61b79fc5e0 <unknown>
0x7f61b79f8cf2 __pthread_cond_timedwait
0x1dfcfa9 kudu::ConditionVariable::WaitUntil()
0xb73bc7 kudu::consensus::RaftConsensus::UpdateReplica()
0xb75128 kudu::consensus::RaftConsensus::Update()
0x92c5d1 kudu::tserver::ConsensusServiceImpl::UpdateConsensus()
0x1d2e8d9 kudu::rpc::GeneratedServiceIf::Handle()
0x1d2efd9 kudu::rpc::ServicePool::RunThread()
0x1ea4a84 kudu::Thread::SuperviseThread()
0x7f61b79f4e25 start_thread
0x7f61b5cd234d __clone
{noformat}
Thread {{93383}} holds the lock, waiting on another conditional variable and
blocks many other threads.
> Contention on the Raft consensus lock can cause tablet service queue overflows
> ------------------------------------------------------------------------------
>
> Key: KUDU-2727
> URL: https://issues.apache.org/jira/browse/KUDU-2727
> Project: Kudu
> Issue Type: Improvement
> Components: perf
> Reporter: William Berkeley
> Priority: Major
>
> Here's stacks illustrating the phenomenon:
> {noformat}
> tids=[2201]
> 0x379ba0f710 <unknown>
> 0x1fb951a base::internal::SpinLockDelay()
> 0x1fb93b7 base::SpinLock::SlowLock()
> 0xb4e68e kudu::consensus::Peer::SignalRequest()
> 0xb9c0df kudu::consensus::PeerManager::SignalRequest()
> 0xb8c178 kudu::consensus::RaftConsensus::Replicate()
> 0xaab816 kudu::tablet::TransactionDriver::Prepare()
> 0xaac0ed kudu::tablet::TransactionDriver::PrepareTask()
> 0x1fa37ed kudu::ThreadPool::DispatchThread()
> 0x1f9c2a1 kudu::Thread::SuperviseThread()
> 0x379ba079d1 start_thread
> 0x379b6e88fd clone
> tids=[4515]
> 0x379ba0f710 <unknown>
> 0x1fb951a base::internal::SpinLockDelay()
> 0x1fb93b7 base::SpinLock::SlowLock()
> 0xb74c60 kudu::consensus::RaftConsensus::NotifyCommitIndex()
> 0xb59307 kudu::consensus::PeerMessageQueue::NotifyObserversTask()
> 0xb54058
> _ZN4kudu8internal7InvokerILi2ENS0_9BindStateINS0_15RunnableAdapterIMNS_9consensus16PeerMessageQueueEFvRKSt8functionIFvPNS4_24PeerMessageQueueObserverEEEEEEFvPS5_SC_EFvNS0_17UnretainedWrapperIS5_EEZNS5_34NotifyObserversOfCommitIndexChangeElEUlS8_E_EEESH_E3RunEPNS0_13BindStateBaseE
> 0x1fa37ed kudu::ThreadPool::DispatchThread()
> 0x1f9c2a1 kudu::Thread::SuperviseThread()
> 0x379ba079d1 start_thread
> 0x379b6e88fd clone
> tids=[22185,22194,22193,22188,22187,22186]
> 0x379ba0f710 <unknown>
> 0x1fb951a base::internal::SpinLockDelay()
> 0x1fb93b7 base::SpinLock::SlowLock()
> 0xb8bff8
> kudu::consensus::RaftConsensus::CheckLeadershipAndBindTerm()
> 0xaaaef9 kudu::tablet::TransactionDriver::ExecuteAsync()
> 0xaa3742 kudu::tablet::TabletReplica::SubmitWrite()
> 0x92812d kudu::tserver::TabletServiceImpl::Write()
> 0x1e28f3c kudu::rpc::GeneratedServiceIf::Handle()
> 0x1e2986a kudu::rpc::ServicePool::RunThread()
> 0x1f9c2a1 kudu::Thread::SuperviseThread()
> 0x379ba079d1 start_thread
> 0x379b6e88fd clone
> tids=[22192,22191]
> 0x379ba0f710 <unknown>
> 0x1fb951a base::internal::SpinLockDelay()
> 0x1fb93b7 base::SpinLock::SlowLock()
> 0x1e13dec kudu::rpc::ResultTracker::TrackRpc()
> 0x1e28ef5 kudu::rpc::GeneratedServiceIf::Handle()
> 0x1e2986a kudu::rpc::ServicePool::RunThread()
> 0x1f9c2a1 kudu::Thread::SuperviseThread()
> 0x379ba079d1 start_thread
> 0x379b6e88fd clone
> tids=[4426]
> 0x379ba0f710 <unknown>
> 0x206d3d0 <unknown>
> 0x212fd25 google::protobuf::Message::SpaceUsedLong()
> 0x211dee4
> google::protobuf::internal::GeneratedMessageReflection::SpaceUsedLong()
> 0xb6658e kudu::consensus::LogCache::AppendOperations()
> 0xb5c539 kudu::consensus::PeerMessageQueue::AppendOperations()
> 0xb5c7c7 kudu::consensus::PeerMessageQueue::AppendOperation()
> 0xb7c675
> kudu::consensus::RaftConsensus::AppendNewRoundToQueueUnlocked()
> 0xb8c147 kudu::consensus::RaftConsensus::Replicate()
> 0xaab816 kudu::tablet::TransactionDriver::Prepare()
> 0xaac0ed kudu::tablet::TransactionDriver::PrepareTask()
> 0x1fa37ed kudu::ThreadPool::DispatchThread()
> 0x1f9c2a1 kudu::Thread::SuperviseThread()
> 0x379ba079d1 start_thread
> 0x379b6e88fd clone
> {noformat}
> {{kudu::consensus::RaftConsensus::CheckLeadershipAndBindTerm()}} needs to
> take the lock to check the term and the Raft role. When many RPCs come in for
> the same tablet, the contention can hog service threads and cause queue
> overflows on busy systems.
> Yugabyte switched their equivalent lock to be an atomic that allows them to
> read the term and role wait-free.
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