Skip to main content

Browse the archive

Revision 80de9004649753d87fa1b2d41127b1401a4c0065 authored by Levi Tamasi on 13 December 2019, 20:45:49 UTC, committed by Levi Tamasi on 17 December 2019, 15:52:22 UTC 
Do not create/install new SuperVersion if nothing was deleted during memtable trim (#6169)
 
Summary:
We have observed an increase in CPU load caused by frequent calls to
`ColumnFamilyData::InstallSuperVersion` from `DBImpl::TrimMemtableHistory`
when using `max_write_buffer_size_to_maintain` to limit the amount of
memtable history maintained for transaction conflict checking. As it turns out,
this is caused by the code creating and installing a new `SuperVersion` even if
no memtables were actually trimmed. The patch adds a check to avoid this.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6169

Test Plan:
Compared `perf` output for

```
./db_bench -benchmarks=randomtransaction -optimistic_transaction_db=1 -statistics -stats_interval_seconds=1 -duration=90 -num=500000 --max_write_buffer_size_to_maintain=16000000 --transaction_set_snapshot=1 --threads=32
```

before and after the change. With the fix, the call chain `rocksdb::DBImpl::TrimMemtableHistory` ->
`rocksdb::ColumnFamilyData::InstallSuperVersion` -> `rocksdb::ThreadLocalPtr::StaticMeta::Scrape`
no longer registers in the `perf` report.

Differential Revision: D19031509

Pulled By: ltamasi

fbshipit-source-id: 02686fce594e5b50eba0710e4b28a9b808c8aa20
1 parent 1d9eae3
Raw File
Vagrantfile 
# Vagrant file
Vagrant.configure("2") do |config|

  config.vm.provider "virtualbox" do |v|
    v.memory = 4096
    v.cpus = 2
  end

  config.vm.define "ubuntu14" do |box|
    box.vm.box = "ubuntu/trusty64"
  end

  config.vm.define "centos65" do |box|
    box.vm.box = "chef/centos-6.5"
  end

  config.vm.define "centos7" do |box|
    box.vm.box = "centos/7"
    box.vm.provision "shell", path: "build_tools/setup_centos7.sh"
  end

  config.vm.define "FreeBSD10" do |box|
    box.vm.guest = :freebsd
    box.vm.box = "robin/freebsd-10"
    # FreeBSD does not support 'mount_virtualbox_shared_folder', use NFS
    box.vm.synced_folder ".", "/vagrant", :nfs => true, id: "vagrant-root"
    box.vm.network "private_network", ip: "10.0.1.10"

    # build everything after creating VM, skip using --no-provision
    box.vm.provision "shell", inline: <<-SCRIPT
      pkg install -y gmake clang35
      export CXX=/usr/local/bin/clang++35
      cd /vagrant
      gmake clean
      gmake all OPT=-g
    SCRIPT
  end

end
back to top