Details
Critical - P2 Description
during test scalability of mongos/shard, found performance regression of mongos due to lock sleep
the traffic is YCSB
- single doc insert
- shard with {_id: hashed}
- total 7 shards, each is 3 member replica set
- writer with 64 threads
- only change mongos binary, 3.1.1/3.1.2 show lower throughput.
3.0.2 3.1.2 throughput 43451 7065
from off-cpu perf analysis
## with master 3.1.2 (c8e2c0546b30621f78cd436d96714cc064bbb8a7)
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-36.26%-- futex_wait_queue_me
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futex_wait
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do_futex
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sys_futex
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system_call_fastpath
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|--100.00%-- __lll_lock_wait
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| |--85.34%-- mongo::StaticShardInfo::reload()
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| | |
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| | |--100.00%-- mongo::Shard::findIfExists(std::string const&)
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| | | mongo::DBClientShardResolver::chooseWriteHost(std::string const&, mongo::ConnectionString*) const
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| | | mongo::BatchWriteExec::executeBatch(mongo::BatchedCommandRequest const&, mongo::BatchedCommandResponse*
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| | | mongo::ClusterWriter::write(mongo::BatchedCommandRequest const&, mongo::BatchedCommandResponse*)
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| | | |
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| | | --100.00%-- mongo::(anonymous namespace)::ClusterWriteCmd::run(mongo::OperationContext*, std::string c
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| | | mongo::Command::execCommandClientBasic(mongo::OperationContext*, mongo::Command*, mongo::Cli
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| | | mongo::Command::runAgainstRegistered(char const*, mongo::BSONObj&, mongo::BSONObjBuilder&, i
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| | | mongo::Strategy::clientCommandOp(mongo::Request&)
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| | | mongo::Request::process(int)
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| | | mongo::ShardedMessageHandler::process(mongo::Message&, mongo::AbstractMessagingPort*, mongo:
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| | | mongo::PortMessageServer::handleIncomingMsg(void*)
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| | | start_thread
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| | --0.00%-- [...]
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| |--14.42%-- mongo::Shard::findIfExists(std::string const&)
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| | mongo::DBClientShardResolver::chooseWriteHost(std::string const&, mongo::ConnectionString*) const
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| | mongo::BatchWriteExec::executeBatch(mongo::BatchedCommandRequest const&, mongo::BatchedCommandResponse*)
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| | mongo::ClusterWriter::write(mongo::BatchedCommandRequest const&, mongo::BatchedCommandResponse*)
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| | --100.00%-- mongo::(anonymous namespace)::ClusterWriteCmd::run(mongo::OperationContext*, std::string const&, mong
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| | mongo::Command::execCommandClientBasic(mongo::OperationContext*, mongo::Command*, mongo::ClientBasic&,
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| | mongo::Command::runAgainstRegistered(char const*, mongo::BSONObj&, mongo::BSONObjBuilder&, int)
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| | mongo::Strategy::clientCommandOp(mongo::Request&)
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| | mongo::Request::process(int)
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| | mongo::ShardedMessageHandler::process(mongo::Message&, mongo::AbstractMessagingPort*, mongo::LastError*
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| | mongo::PortMessageServer::handleIncomingMsg(void*)
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| | start_thread
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| --0.24%-- [...]
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--0.00%-- [...]
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