async_gather.py

# -----------------------------------------------------------------------------
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#
# This software is dual-licensed to you under the Universal Permissive License
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# the following applies:
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# Licensed under the Apache License, Version 2.0 (the "License");
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# See the License for the specific language governing permissions and
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# -----------------------------------------------------------------------------

# -----------------------------------------------------------------------------
# async_gather.py
#
# Demonstrates using a connection pool with asyncio and gather().
#
# Multiple database sessions will be opened and used by each coroutine.  The
# number of connections opened can depend on the speed of your environment.
# -----------------------------------------------------------------------------

import asyncio

import oracledb
import sample_env

# Number of coroutines to run
CONCURRENCY = 5

# Query the unique session identifier/serial number combination of a connection
SQL = """SELECT UNIQUE CURRENT_TIMESTAMP AS CT, sid||'-'||serial# AS SIDSER
         FROM v$session_connect_info
         WHERE sid = SYS_CONTEXT('USERENV', 'SID')"""


# Show the unique session identifier/serial number of each connection that the
# pool opens
async def init_session(connection, requested_tag):
    res = await connection.fetchone(SQL)
    print(res[0].strftime("%H:%M:%S.%f"), "- init_session SID-SERIAL#", res[1])


# The coroutine simply shows the session identifier/serial number of the
# connection returned by the pool.acquire() call
async def query(pool):
    async with pool.acquire() as connection:
        await connection.callproc("dbms_session.sleep", [1])
        res = await connection.fetchone(SQL)
        print(res[0].strftime("%H:%M:%S.%f"), "- query SID-SERIAL#", res[1])


async def main():
    pool = oracledb.create_pool_async(
        user=sample_env.get_main_user(),
        password=sample_env.get_main_password(),
        dsn=sample_env.get_connect_string(),
        min=1,
        max=CONCURRENCY,
        session_callback=init_session,
    )

    coroutines = [query(pool) for i in range(CONCURRENCY)]

    await asyncio.gather(*coroutines)

    await pool.close()


asyncio.run(main())