Webware for Python

On 8/22/07, Kevin J. Rice <throw@...> wrote:
> Hello!
>
> We're using Webware 0.9.1 and 0.9.4 in various places, so these questions
> apply to both versions:
>
> We're wondering 2 things:
>
> 1.  Can we find the current running request for each thread, when that
> request started, and view the queue of requests not yet assigned to any
> thread?
>
> 2.  Can we automatically identify a request being processed for more than a
> certain amount of time and terminate that request?    This is a sort of a
> timeout setting concept.

These are interesting questions, but I haven't needed these
capabilities myself so I don't know off the top of my head. Christoph
might know and comment when he gets back from vacation, but otherwise
I suggest digging into the code to see what you find. I suspect you
could get both.

-Chuck

Kevin J. Rice wrote:
> 1. Can we find the current running request for each thread, when that
> request started, and view the queue of requests not yet assigned to
> any thread?

The pending request are in the application._server._requestQueue. You 
can also find in the _processing attribute whether a thread is currently 
processing a request. But it seems you cannot find which request handler 
is currently processed by that thread.

> 2. Can we automatically identify a request being processed for more
> than a certain amount of time and terminate that request? This is a
> sort of a timeout setting concept.

If you could get the request handler associated with a thread, then you 
could get its starting time from its _startTime attribute and you could 
terminate the thread if it takes too long. But as I said I think the 
former is not possible.

The code is in ThreadedAppServer. If you have ideas for improvement, let 
me know.

-- Christoph

On 8/22/07, Kevin J. Rice <throw@...> wrote:

> Hello!
>
> We're using Webware 0.9.1 and 0.9.4 in various places, so these questions
> apply to both versions:
>
> We're wondering 2 things:
>
> 1.  Can we find the current running request for each thread, when that
> request started, and view the queue of requests not yet assigned to any
> thread?
>
> 2.  Can we automatically identify a request being processed for more than a
> certain amount of time and terminate that request?    This is a sort of a
> timeout setting concept.
>   


I asked similar questions about 12 months ago so it might be worth 
having a look in the mailing list archive.  In the end I concluded that 
terminating threads requires a Python extension that I did not want the 
trouble of integrating (but which may be included in a future release).  
As regards active requests, I have implemented a system that allows me 
to find out what my threads are doing.  It works like this:

In the base class for all my servlets, I include:

class MyPage(PSPPage):
  def awake(self, transaction):
    PSPPage.awake(self, transaction)
    thread = threading.currentThread()
    thread.status = dict()
    self.setThreadStatus('awoke', time.asctime())

  def sleep(self, trans):
    PSPPage.sleep(self, trans)
    self.setThreadStatus('awoke', 'asleep')

  def setThreadStatus(self, name, value):
    threading.currentThread().status[name] = value

Any servlet can use self.setThreadStatus() to record tidbits about what 
it is doing.

Then I have a PSP servlet that displays the status for all threads:

<%@page extends="WebKit.Page"%>
<%@page method="writeContent"%>
<%@page imports="cgi, WebKit.ThreadedAppServer, threading"%>

<%
server = WebKit.ThreadedAppServer.server
%>
Active threads according to server: <%=server.activeThreadCount()%>
<%
allThreads = server._threadPool
notProcessing = 0
curThread = threading.currentThread()
threads = filter(lambda t: t != curThread, allThreads)
for thread in threads:
%>
  <%if thread.processing:%>
    <%
    status = thread.__dict__.get('status', None)
    if status is None:%>
      <p>No status information available.</p>
      <%end%>
    <%else:%>
      <table>
      <%for key, value in status.items():%>
        <tr><td><%=key%></td><td><%=cgi.escape(str(value))%></td></tr>
        <%end%>
      </table>
      <%end%>
    <%end%>
  <%else: notProcessing = notProcessing + 1%>
  <%end%>
<p>Not processing: <%=notProcessing%> +1 for thread servicing this 
request</p>

Christoph Zwerschke wrote:
 > Kevin J. Rice wrote:
 >> 1. Can we find the current running request for each thread, when that
 >> request started, and view the queue of requests not yet assigned to
 >> any thread?
 >
 > The pending request are in the application._server._requestQueue. You
 > can also find in the _processing attribute whether a thread is currently
 > processing a request. But it seems you cannot find which request handler
 > is currently processed by that thread.

We could make a simple change to ThreadedAppServer by setting the 
_processing attribute to the currently processed handler or None instead 
of True/False. Would this be helpful?

-- Christoph