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<DIV dir=ltr align=left><FONT size=2>
<P>Hi Ian,</P>
<P></P>
<P>You can also use the standard "thread" or "threading" Python modules, so that
you don't depend on _apache.</P>
<P></P>
<P>The approach you have is secure but it has the downside of denying any
concurrent access to the database (if I understand your code correctly). I don't
know SQLite very much, but it seems that it can handle multithreaded access to
the database (see </FONT><A href="http://www.sqlite.org/lockingv3.html"><U><FONT
color=#0000ff size=2>http://www.sqlite.org/lockingv3.html</U></FONT></A><FONT
size=2>), so it would be better to leverage this. The solution is a connection
pool.</FONT></P>
<P><FONT size=2></FONT></P>
<P><FONT size=2>You can write a connection pool using the threading.RLock and
threading.Condition to protect the critical sections, namely the acquisition of
database connections. The end result is that each thread is guaranteed to have a
connection of its own, which can be reused as soon the thread release it to the
pool. It usually speeds things up, and I guess it would be especially useful
with SQLite. I've been using such a connection pool for a few months now and
have never looked back since. In your case, it seems that you wrap the SQLite
connection with an UserDatabase object, so maybe <SPAN
class=221363108-07072004>you should pool UserDatabase instances instead of
SQLite connections.</SPAN></FONT></P>
<P><FONT size=2></FONT></P>
<P><FONT size=2>Best regards,</FONT></P>
<P><FONT size=2></FONT></P>
<P><FONT size=2>Nicolas Lehuen</FONT></P></DIV><BR>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader lang=fr dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>De :</B> mod_python-bounces@modpython.org
[mailto:mod_python-bounces@modpython.org] <B>De la part de</B> Iain
Mackay<BR><B>Envoy� :</B> mardi 6 juillet 2004 21:18<BR><B>� :</B>
mod_python@modpython.org<BR><B>Objet :</B> [mod_python] Apache on Windows
and concurrency<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Thanks Grisha for being so quickly
on the case.</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Session.py also includes the
solution to my problem, using the Apache global locks.</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I now have the following code to
protect a section of script that is using the database connection (it
uses SQLite but would apply mutatis mutandis to another database). I have
restored multi-threading and all works smoothly. </SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">If this is the best way to do
this, it might be worth a mention in the next release of the documentation. I
suppose ideally application code shouldn�t use _apache.</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">from mod_python import
apache</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">import _apache</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">import re</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">import sqlite</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">import
userdatabase</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">import sys</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">users = None</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">apache.log_error ("userHandler
initialising", apache.APLOG_INFO)</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">def beginDB
(req):</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
_apache._global_lock(req.server, None, 0)</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
global users</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
if not users:</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
try:</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
try:</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
defaultUser = req.get_options ()["defaultUser"]</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
except:</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
defaultUser = "guest"</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
users = userdatabase.UserDatabase\</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
(sqlite.connect (req.get_options ()["dbFile"],</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
077, autocommit=1), defaultUser)</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
except:</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
(type, value, tb) = sys.exc_info()</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
apache.log_error ("Cannot access user database: %s (%s)" % (type,
value),</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
apache.APLOG_ERR)</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">def endDB (req):</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
_apache._global_unlock(req.server, None, 0)</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P></DIV></BLOCKQUOTE></BODY></HTML>