This is a simple benchmark for various asynchronous Python MySQL
client libraries.

The client libraries tested here are:

- Twisted's adbapi which uses the MySQL client library written in C.
- the pure Python txMySQL asynchronous client library
- my own adb.py interface using tornado and adisp

The adbapi and txMySQL libraries assume they're running on the Twisted
framework. The benchmarks allow you to run different reactor
implementations:

- Twisted's default reactor
- the Tornado-based reactor for Twisted

The adb.py library is designed to run directly on top of Tornado and
uses adisp.py to make asynchronous programming a lot easier.

Here is how you write asynchronous database code with the adb and
adisp modules:

from adisp import process
from adb import Database

    def __init__(self):
        self.adb = Database(driver="psycopg2",
                            host='DATABASE_HOST',
                            database='DATABASE_DB',
                            user='DATABASE_USER',
                            password='DATABASE_PASSWD',
                            num_threads=3,
                            tx_connection_pool_size=2,
                            queue_timeout=0.001)


    @process
    def someFunctionInvokedFromIOLoop(self):
        # Drop the table if it exists
        yield self.adb.runOperation("drop table if exists benchmark")
	# Create a table to insert the data into
        yield self.adb.runOperation("""
          create table benchmark (
            userid int not null primary key,
            data VARCHAR(100)
          );
        """)
        rows_to_insert = 100000
        # Insert some rows in parallel
        start_time = time.time()
        stmts = []
        for i in xrange(rows_to_insert):
            stmts.append(
                ("insert into benchmark (userid, data) values (%s, %s)",
                 (i, i)))
        numrows = yield map(self.adb.runOperation, stmts)
        end_time = time.time()

        rows = yield self.adb.runQuery("select count(*) from benchmark")
        print 'inserted %s records, time taken = %s seconds' % \
            (rows, end_time - start_time)

You can also use transactions:

    @process
    def transactions(self):
        txId = yield self.adb.beginTransaction()
        yield self.adb.runOperation(
            "insert into mytable (userid, data) values (%s, %s)",
            (1, "test"),
            txId)
        yield self.adb.commitTransaction(txId)

To rollback a transaction, use rollbackTransaction(txId) instead of
commitTransaction().



The command line options for the benchmark are the following:

  --db                The database to use
  --dbhost            Database host
  --dbpasswd          Database user's password
  --dbuser            Database user to use
  --pool_size         Database connection pool size
  --use_adb           Use adb.py database module
  --use_adbapi        Use twisted's adbapi module
  --use_tornado       Use tornado twisted reactor instead of twisted's reactor
  --use_txmysql       Use txMySQL database module. Only works with Twisted and
                      MySQL

Below are some benchmark results. The benchmark program runs on my
Hackintosh Core i7-2600K 3.4GHz (4 cores 8 threads) running MacOS X
10.6.7. The database servers were run on the same machine. The
benchmark connects to the databases using TCP sockets instead of Unix
domain sockets.

The MySQL server version used was 5.1, while Postgres version was
9.0.4.

The pool size specified was --pool_size=10

Here are the times in seconds reported by the program:

MySQL:
      	 Tornado   Twisted
adb      11.79       N/A
adbapi   18.99     19.74
txMySQL  45.19     43.80 (numbers from a previous version of this benchmark)


Postgres:
      	 Tornado   Twisted
adb       9.03       N/A
adbapi   16.49     17.00



Conclusion
==========

The new adb.py module running on top of Tornado is 40% faster than
Twisted's adbapi. As a bonus, in this benchmark the memory usage of
adb was 140MB versus the 300MB used by Twisted's adbapi.

When used with adisp, programming asynchronous database operations
with adb and Tornado is a real breeze, since you no longer need to
worry about creating callbacks to handle the results from the
database.


References
==========

The txMySQL implementation tested against is available in the main
trunk at:

https://github.com/hybridlogic/txMySQL

The Tornado-based reactor implementation used is available in the main
trunk at:

https://github.com/facebook/tornado