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#------------------------------------------------------------------------------

# ConnectionPool.py

# This script demonstrates the use of connection pooling in cx_Oracle. Pools

# can significantly reduce connection times for long running applications that

# repeatedly open and close connections. Internal features help protect against

# dead connections, and also aid use of Oracle Database features such as FAN

# and Application Continuity.

# The script uses threading to show multiple users of the pool. One thread

# performs a database sleep while another performs a query. A more typical

# application might be a web service that handles requests from multiple users.

# Applications that use connections concurrently in multiple threads should set

# the 'threaded' parameter to True. Note only one operation (such as an execute

# or fetch) can take place at a time on each connection.

# Also see SessionCallback.py.

#------------------------------------------------------------------------------

import cx_Oracle

import sample_env

import threading

# Create a Connection Pool

pool = cx_Oracle.SessionPool(user=sample_env.get_main_user(),

password=sample_env.get_main_password(),

dsn=sample_env.get_connect_string(), min=2,

max=5, increment=1, threaded=True)

# dbms_session.sleep() replaces dbms_lock.sleep() from Oracle Database 18c

with pool.acquire() as conn:

sleep_proc_name = "dbms_session.sleep" \

if int(conn.version.split(".")[0]) >= 18 \

else "dbms_lock.sleep"

def TheLongQuery():

with pool.acquire() as conn:

cursor = conn.cursor()

cursor.arraysize = 25000

print("TheLongQuery(): beginning execute...")

cursor.execute("""

select *

from

TestNumbers

cross join TestNumbers

cross join TestNumbers""")

print("TheLongQuery(): done execute...")

while True:

rows = cursor.fetchmany()

if not rows:

break

print("TheLongQuery(): fetched", len(rows), "rows...")

print("TheLongQuery(): all done!")

def DoALock():

with pool.acquire() as conn:

cursor = conn.cursor()

print("DoALock(): beginning execute...")

cursor.callproc(sleep_proc_name, (5,))

print("DoALock(): done execute...")

thread1 = threading.Thread(None, TheLongQuery)

thread1.start()

thread2 = threading.Thread(None, DoALock)

thread2.start()

thread1.join()

thread2.join()

print("All done!")

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