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Masstree

This is the source release for Masstree, a fast, multi-core key-value store. This document describes how to run Masstree and interpret its results.

Note: I'm currently working on refactoring Masstree to use synchronization primitives from the C++ standard library wherever possible, with the end goal being to make the system portable to all major platforms. I have an unmodified version of the master branch with a Docker file for a Linux image on the branch jeremy-main and my working changes are on the branch jeremy-standard.

Contents

  • MTDIR: this directory
  • MTDIR/doc: Masstree algorithm specification

Installation

Masstree is tested on Debian, Ubuntu and Mac OS X. To build from source:

$ ./bootstrap.sh
$ ./configure
$ make

For performance measurements, you should disable assertions.

$ ./configure --disable-assertions

Masstree needs a fast malloc, and can link with jemalloc, Google’s tcmalloc, Hoard, or our own Flow allocator. It will normally choose jemalloc or tcmalloc, if it finds them. To use a specific memory allocator:

./configure --with-malloc=<jemalloc|tcmalloc|flow|hoard>

Flow is our re-implementation of Streamflow allocator, and may be open-sourced in future.

See ./configure --help for more configure options.

Testing

The simplest way to try out Masstree is the ./mttest program. This test doesn’t involve disk or network overhead.

$ ./mttest
1/1 rw1/m
0: now getting
1: now getting
0: {"table":"mb","test":"rw1","trial":0,"thread":0,"puts":13243551,"puts_per_sec":1324492.05531,"gets":13243551,"gets_per_sec":1497267.13928,"ops":26487102,"ops_per_sec":1405590.1258}
1: {"table":"mb","test":"rw1","trial":0,"thread":1,"puts":13242601,"puts_per_sec":1324397.45602,"gets":13242601,"gets_per_sec":1481151.35726,"ops":26485202,"ops_per_sec":1398395.26601}
EXPERIMENT x0

The test starts a process which hosts a Masstree, and generates and executes queries over the tree. It uses all available cores (two in the above example). The test lasts for 20 seconds. It populates the key-value store with put queries during first 10 seconds, and then issues get queries over the tree during the next 10 seconds. See kvtest_rw1_seed in kvtest.hh for more details about the workload. For a list of workloads, run ./mttest --help.

The output summarizes the throughput of each core. The 1/1 rw1/m line says that mttest is running the first trial (out of one trials), of the rw1 workload using Masstree (m for short) as the internal data structure. When the run completes (the now getting lines are printed during the test), mttest generates a per-core throughput summary, as indicated by 0: {"table":"mb","test":"rw1",...}.

If you redirect its standard output to a file or pipe, mttest will produce gnuplot source that plots the median per-core throughput. Each candlestick has five points for the min,20%,50%,70%,max of the corresponding metrics among all threads.

mttest also writes the output as JSON into file for further analysis. For example, after ./mttest, notebook-mttest.json will contain:

{
  "experiments":{
    "x0":{
      "git-revision":"673994c43d58d46f4ebf3f7d4e1fce19074594cb",
      "time":"Wed Oct 24 14:54:39 2012",
      "machine":"mat",
      "cores":2,
      "runs":["x0\/rw1\/mb\/0"]
    }
  },
  "data":{
    "x0\/rw1\/mb\/0":[
      {
        "table":"mb",
        "test":"rw1",
        "trial":0,
        "thread":0,
        "puts":13243551,
        "puts_per_sec":1324492.05531,
        "gets":13243551,
        "gets_per_sec":1497267.13928,
        "ops":26487102,
        "ops_per_sec":1405590.1258
      },
      {
        "table":"mb",
        "test":"rw1",
        "trial":0,
        "thread":1,
        "puts":13242601,
        "puts_per_sec":1324397.45602,
        "gets":13242601,
        "gets_per_sec":1481151.35726,
        "ops":26485202,
        "ops_per_sec":1398395.26601
      }
    ]
  }
}

Run ./mttest --help for a list of tests and options.

Network testing

mtclient supports almost the same set of workloads that mttest does, but it sends queries to a Masstree server over the network.

To start the Masstree server, run:

$ ./mtd --logdir=[LOG_DIRS] --ckdir=[CHECKPOINT_DIRS]
mb, Bag, pin-threads disabled, logging enabled
no ./kvd-ckp-gen
no ./kvd-ckp-0-0
no ./kvd-ckp-0-1
2 udp threads
2 tcp threads

LOG_DIRS is a comma-separated list of directories storing Masstree logs, and CHECKPOINT_DIRS is a comma-separated list of directories storing Masstree checkpoints. Masstree will write its logs to the LOG_DIRS and periodic checkpoints to the CHECKPOINT_DIRS. (Both logging and multithreading are performed using multiple cores, so there are several log and checkpoint files.) Alternatively, run ./mtd -n to turn off logging.

To run the rw1 workload with mtclient on the same machine as mtd, run:

$ ./mtclient -s 127.0.0.1 rw1
tcp, w 500, test rw1, children 2
0 now getting
1 now getting
0 total 7632001 763284 put/s 1263548 get/s
1 total 7612501 761423 put/s 1259847 get/s
{"puts":7632001,"puts_per_sec":763284.211682,"gets":7632001,"gets_per_sec":1263548.30195,"ops":15264002,"ops_per_sec":951678.506329}
{"puts":7612501,"puts_per_sec":761423.014367,"gets":7612501,"gets_per_sec":1259847.22076,"ops":15225002,"ops_per_sec":949182.006246}
total 30489004
puts: n 2, total 15244502, average 7622251, min 7612501, max 7632001, stddev 13789
gets: n 2, total 15244502, average 7622251, min 7612501, max 7632001, stddev 13789
puts/s: n 2, total 1524707, average 762354, min 761423, max 763284, stddev 1316
gets/s: n 2, total 2523396, average 1261698, min 1259847, max 1263548, stddev 2617