Hi,
Our first priority is to make Tomcat to work in normal conditions with good
intentioned users. We will
worry later about DOS (as long as we don't introduce new vulnerabilities).
Yes, we tested the timeout patch all day yesterday with a production system
with real users and normal load and
all the hanging threads and connections was cleaned up perfectly (we are
using 'netstat' to
get the number of HTTP connections and 'ps' to get the number of thread and
all is graphed around the clock by MRTG). We are running with a relatively
timeout of 5 minutes (50*60*1000) just to be on the safe side but a shorter
one can be used.
Note that I am in no way and expert in Tomcat nor do I claim to understand
all the implications of the patch so we need some qualified person to
understand the implication and make sure it does not break anything. For
example, if another service like Ajp uses this connection pool for long term
connections that need to wait long periods for a data from some client (e.g.
a front end web server, client side applets, etc), the patch will break it.
The patch assumes that the connections are should never be idle for a long
period of time.
As for Apache, it supports a request timeout (see
http://httpd.apache.org/docs/mod/core.html#timeout) and this will
will eventually cleanup hanging connections. The timeout in this case is
longer because it is for the entire request and the cleanup will be slower.
Implementing a similar query timeout in Tomcat may require things like
asynchronous thread kill (yuck) or some synchronous termination of the
worker threads, for example by closing the sockets they are waiting on (I
think this will release the socketRead() but I am not sure). But this is of
course a more involved change than simply adding the timeout statement.
Having an asynchronous I/O may help here (see Bug Parade
http://developer.java.sun.com/developer/bugParade/bugs/4075058.html).
BTW, does Tomcat 4.X has the same problem ?
Tal
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, March 20, 2001 7:03 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Bug 1006, what's next ?
>
>
> Hi,
>
> I had a (long) weekend without computers. But I still found one and read
> the mail once - and your report is very serious and important ( and not
> easy to fix ). You have (at least ) my full attention. The read
> timeout will be checked in soon - but the general problem ( with a servlet
> hanging a thread ) is very hard to resolve (or I don't know any good
> solution ).
>
> We could stop setting an upper limit on the thread count ( we still have
> the OS upper limit ), and we could also use the (dangerous,
> deprecated) suspend/terminate on the thread that is taking too much time.
>
> Have you tried any fix ? The timeout will not resolve the "bursts" ( and
> high-loaded servers ) - unless it is very short.
>
> BTW, this is not a tomcat-specific problem ( I would guess Apache does
> have the same issue - and we need to find how they deal with that ).
>
> Costin
>
>
> On Tue, 20 Mar 2001, Tal Dayan wrote:
>
> >
> > Two days ago I filed a bug report regarding a sever hanging problem in
> > PollTcpEndpoint of Tomcat 3.x. The bug is
> > at http://nagoya.apache.org/bugzilla/show_bug.cgi?id=1006 and
> also include a
> > suggestion for a patch.
> >
> > Since then I did not notice any change in the status or
> resolution of the
> > bug report nor any
> > indication that it got anywhere.
> >
> > 1. Is this is the right place to file the bug ?
> >
> > 2. Is the bug filed correctly ?
> >
> > 3. Should I do anything else to make sure the bug gets the
> attention of the
> > relevant maintainers ?
> >
> > Thanks,
> >
> > Tal
> >
> >
>
>
