Pequod

This is the source release for Pequod, a fast, distributed key-value cache with builtin support for materialized views. Pequod is a research prototype and should not be used in any production environment. For background on Pequod's design, see the publication:

Easy Freshness with Pequod Cache Joins

Contents

• PQDIR This directory.
• PQDIR/src Pequod source.
• PQDIR/lib Supporting source.
• PQDIR/app Experiment application source.
• PQDIR/scripts Testing scripts.
• PQDIR/vis Debugging visualization.

Building

Pequod builds on Linux and Mac OSX. To build:

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

Pequod requires a C++11 compatible compiler, and the Apple-supplied compiler might not be suitable for building on OSX. To use an alternate compiler (such as one installed with homebrew), specify the CXX variable at configuration time:

$ ./configure CXX='g++-4.8 -std=gnu++11'

For better deubgging with gdb, disable compiler optimizations:

$ make NO_OPT=1

For performance measurements, you should disable debugging features:

$ ./configure --disable-tamer-debug
$ make NDEBUG=1

Pequod looks for alternate malloc libraries (jemalloc and tcmalloc) and will use one if found.

Integration with other tools, like Postgres, memcached and Redis, is determined automatically at configuration time depending on the presence of client libraries on the host system.

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

Testing

After compilation, test the build by running unit tests:

$ ./obj/pqserver --tests

To run an individual test, name it explicitly:

$ ./obj/pqserver test_simple

Running an application in a single process (such as twitternew):

$ ./obj/pqserver --twitternew

will produce JSON output similar to:

{
  "log": {
    "mem_max_rss_mb": [
      [6,129]
    ],
    "utime_us": [
      [6,1018973]
    ],
    "stime_us": [
      [6,53985]
    ],
    "cpu_pct": [
      [6,0]
    ]
  },
  "server_logs": null,
  "server_stats": [
    {
      "store_size": 720901,
      "source_ranges_size": 8484,
      "join_ranges_size": 1,
      "valid_ranges_size": 3483,
      "server_max_rss_mb": 155,
      "server_user_time": 0.539933,
      "server_system_time": 0.011884,
      "server_wall_time": 0.551801,
      "server_wall_time_insert": 0.132986,
      "server_wall_time_validate": 0.107239999999,
      "server_wall_time_evict": 0,
      "server_wall_time_other": 0.311575000002,
      "tables": [
        {"name":"p","ninsert":1230,"store_size":1230,"source_ranges_size":5001,"nvalidate":1800,"nsubtables":5000},
        {"name":"s","ninsert":563575,"store_size":563305,"source_ranges_size":3483,"nvalidate":3483,"nsubtables":5000},
        {"name":"t","nmodify":156892,"nmodify_nohint":3483,"store_size":156366,"sink_ranges_size":3483,"nsubtables":3483}
      ]
    }
  ],
  "nposts": 1230,
  "nbackposts": 0,
  "nsubscribes": 13173,
  "nchecks": 79075,
  "nfull": 9766,
  "nposts_read": 145572,
  "nactive": 3483,
  "nlogouts": 6522,
  "user_time": 0.524327,
  "system_time": 0.011857,
  "wall_time": 0.536175
}

Network Testing

Pequod can be started as a server, listening on a port for clients:

$ ./obj/pqserver -kl=7777 &

and to connect a client to a server and run an application:

$ ./obj/pqserver -c=7777 --twitternew

which will produce JSON results similar to the inline example above.

Helper scripts can execute larger deployments on a multiprocessor and on Amazon EC2. They are in the scripts directory. For example, the command:

$ ./scripts/local.py -c 3 basic

will run a short Twitter benchmark using 3 Pequod cache servers and 1 client. The results of the experiment will be stored in PQDIR/results in a unique directory and linked to PQDIR/last.

The scripts take as input the experiment definitions (see PQDIR/scripts/exp) using the -e parameter. The number of cache servers to run is given by -c, and if a two-tier deployment is desired, -b will designate the number of base servers. The number of clients used to execute the test workload is given with -g.

The JSON output is directed to output_app_0.json if one client is used, and aggregate_output_app.json if more than one client is used. A log file (prefixed with fart_) is generated for each Pequod server and client in the experiment.

The above command should print something like:

Running experiment in test 'basic'.
./obj/pqserver -H=results/exp_2014_04_07-19_24_12/hosts.txt -B=1 -P=twitternew-text -kl=7000
./obj/pqserver -H=results/exp_2014_04_07-19_24_12/hosts.txt -B=1 -P=twitternew-text -kl=7001
./obj/pqserver -H=results/exp_2014_04_07-19_24_12/hosts.txt -B=1 -P=twitternew-text -kl=7002
./obj/pqserver -H=results/exp_2014_04_07-19_24_12/hosts.txt -B=1 -P=twitternew-text -kl=7003
Initializing cache servers.
./obj/pqserver --twitternew --verbose --no-binary --initialize --no-populate --no-execute -H=results/exp_2014_04_07-19_24_12/hosts.txt -B=1
Populating backend.
./obj/pqserver --twitternew --verbose --no-binary --no-initialize --no-execute --popduration=0 --nusers=1000 -H=results/exp_2014_04_07-19_24_12/hosts.txt -B=1
Starting app clients.
./obj/pqserver --twitternew --verbose --no-binary --no-initialize --no-populate --nusers=1000 --duration=100000 --fetch -H=results/exp_2014_04_07-19_24_12/hosts.txt -B=1
Done experiment. Results are stored at results/exp_2014_04_07-19_24_12/basic/

For other script options, refer to the python code.

3rd Party Benchmarks

The 3rd party benchmark tool memtier_benchmark is included as a submodule. It is modified to include Pequod as a protocol option. It can be built after Pequod is built (it relies on Pequod files to be generated first):

$ make memtier

The benchmark can be executed manually against a running Pequod server, but it is probably easier to use the PQDIR/scripts/memtier.py script. See the Python code for details.

Support

This is research code, and you use it at your own risk. Requests for support by email may be ignored.

License

Pequod is released under the BSD license. See the PQDIR/LICENSE file for details.