[cx-oracle-users] cx_oracle does not close TCP/IP connections on close(); relies on Python garbage collection

[Michael B. <mi...@zz...>]

I'm assuming this is intentional behavior, as illustrated by the script below.    Wondering what the rationale is for delaying the close of a connection until the object is garbage collected - in particular, this makes it difficult for applications that are attempting to manage the total number of TCP connections opened, where the actual connection object might still be referenced somewhere.    Such an approach is even more problematic if and when cx_Oracle begins to be run on platforms such as Pypy where reference counting GC isn't used, as garbage collection can be delayed entirely for any amount of time.

This is cx_Oracle 5.1, script is tested on Mac OSX as well as Fedora 14.  The script creates one connection, closes it, illustrates what network connections are set up to port 1521.  Then del is called, network connections are illustrated again.   On both platforms, the one ESTABLISHED connection goes to TIME_WAIT only after "del c" is called.

import os
import cx_Oracle
import time

print "Version:", cx_Oracle.version

c = cx_Oracle.connect(
    dsn='(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))(CONNECT_DATA=(SID=xe)))', 
    password='tiger', 
    user='scott', 
)

c.close()
time.sleep(.01)

print "-" * 20
os.system("netstat -nt | grep 1521")

del c
time.sleep(.01)

print "-" * 20
os.system("netstat -nt | grep 1521")


output on OSX:

Version: 5.1
--------------------
tcp4       0      0  127.0.0.1.1521         127.0.0.1.60111        ESTABLISHED
tcp4       0      0  127.0.0.1.60111        127.0.0.1.1521         ESTABLISHED
--------------------
tcp4       0      0  127.0.0.1.1521         127.0.0.1.60111        CLOSE_WAIT
tcp4       0      0  127.0.0.1.60111        127.0.0.1.1521         FIN_WAIT_2


output on Fedora 14 (this is the server where Oracle is running, so some 1521s are already present):

Version: 5.1
--------------------
tcp        0      0 66.228.40.238:48786         66.228.40.238:1521          ESTABLISHED 
tcp        0      0 127.0.0.1:49302             127.0.0.1:1521              ESTABLISHED 
tcp        0      0 127.0.0.1:1521              127.0.0.1:49302             ESTABLISHED 
tcp        0      0 66.228.40.238:1521          66.228.40.238:48786         ESTABLISHED 
--------------------
tcp        0      0 66.228.40.238:48786         66.228.40.238:1521          ESTABLISHED 
tcp        0      0 127.0.0.1:49302             127.0.0.1:1521              TIME_WAIT   
tcp        0      0 66.228.40.238:1521          66.228.40.238:48786         ESTABLISHED