[mod_python] Multiple returns to client

Jim Gallacher jpg at jgassociates.ca
Wed Sep 6 07:45:14 EDT 2006

Ethan Toan Ton wrote:
> Mike,
> Thanks for the help.  req.flush() works for sending out the data. 
> Unfortunately, at the same time, my python program is making requests and
> receiving data from other http sources at the same time.  When I run the
> req.flush(), it outputs some of the incoming data as well.  Not sure why
> that is happening.

That doesn't make any sense at all. Perhaps you can give a concrete 
example? Method req.flush() is a simple wrapper around the Apache 
ap_rflush() call.

Note that you can also use req.write(some_string, flush=1) to 
immediately flush the output. For flush=1 causes ap_rflush() to be 
called as well.


> Ethan
>> Your output is buffered in multiple stages. In most cases, you can call
>> "req.flush()" to send data to the client. This will usually work, unless
>> you have a module or a filter installed that collects output until the
>> final stage.
>> For example, this pattern shows how to send output from a slow query
>> back to the user, so that he can see the results as they come back. By
>> calling req.flush() at smart points, we make sure there's some feedback
>> quite efficiently.
>> ...
>> req.write("<P>Results:</P><table><tr><th>Name</th><th>Date</th></tr>")
>> req.flush()
>> c=database.cursor()
>> c.execute("SELECT name,date FROM persons")
>> while 1:
>>     data = c.fetchmany()
>>     if not data:
>>         break
>>     for row in data:
>>         req.write("<tr><td>%s</td><td>%s</td></tr>" % row)
>>     req.flush()
>> req.write("</table>")
>> ...
>> Mike Looijmans
>> Philips Natlab / Topic Automation
>> Ethan Toan Ton wrote:
>>> I was wondering if anyone knew of a way to return multiple times to a
>>> client using a Mod-Python event handler.  Using the req.write() method
>>> does nothing until the actual return statement sends all the data in one
>>> message back to the client.  So before you get to the actual return
>>> statement, can you output back to them more than once?
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