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From Michael Kleinhenz <m.kleinh...@tarent.de>
Subject Re: No more than 500 threads on Windows 2003?
Date Fri, 01 Jul 2005 09:15:08 GMT

mmh..

"You may hear the terms "green threads" and "native threads". This
refers to the Unix implementations of Java. When Java 1.0 first
came out on Solaris, it did not use the native Solaris library
libthread.so to support threads. Instead it used runtime thread
support that had been written in Java for an earlier project
code-named "Green." That thread library came to be known as "green
threads."

"Thread support on Windows used the native libraries from the start,
but on Solaris green threads were used. That meant that threaded
programs running on Solaris didn't get the benefit of the native
libraries. In particular, if your Java program was executing on a
multi processor Solaris system, it was never the case that different
threads could execute truly in parallel by being dispatched on
different processors. There are other benefits too, to do with more
efficient mapping of I/O system calls."

-> Just Java 2, Fourth Edition, by Peter van der Linden

So Windows always uses native threads. Seems to me like a Windows system
or license limit. I have already asked tech support of the hosting
provider who installed the server, but no answer yet.

-- Michael


On Fri, Jul 01, 2005 at 11:02:44AM +0200, delbd wrote:
> I may be wrong, but as far as my knowledge goes on green threads, this is just a matter
of 
> dedactivating native system thread to use an internal threading / sheduling system in
the jvm.
> I see no reason why this wouldn't exist on windows version of jvm.
> 
> Le Vendredi 1 Juillet 2005 10:39, Michael Kleinhenz a écrit :
> > 
> > as far as I know, the concept of green and native threads only applies
> > to Unix systems...?
> > 
> > -- Michael
> > 
> > 
> > On Fri, Jul 01, 2005 at 10:44:38AM +0200, delbd wrote:
> > > Maybe you could switch the jvm to green threads ?
> > > Le Vendredi 1 Juillet 2005 09:57, Michael Kleinhenz a écrit :
> > > > 
> > > > maybe. I can't confirm, because it fails so fast, I can't take a look
in 
> > > > the manager app to see the exact number of threads when it begins hanging.
> > > > 
> > > > I experienced the problem with Tomcat 5.0.28+JDK1.4.2 and Tomcat 
> > > > 5.5.9+JDK1.5.0 while my (somewhat slower) notebook can do 800+ threads

> > > > with Debian and 5.0.28+1.4.2 without problems.
> > > > 
> > > > Seems to me like a Windows problem, but I can't find anything in the 
> > > > docs nor via Google.. ;-(
> > > > 
> > > > Windows sucks..
> > > > 
> > > > -- Michael
> > > > 
> > > > delbd schrieb:
> > > > > Just by curiosity, does it have something like '511 Threads is ok
but 512 fails?' :D
> > > > > Le Jeudi 30 Juin 2005 15:09, Michael Kleinhenz a écrit :
> > > > > 
> > > > >>Hi,
> > > > >>
> > > > >>I'm currently integrating a SOAP-based middleware on Tomcat (5.5.9)
with
> > > > >>Sun JDK 1.5.0_02 and get into problems when using maxThreads with
a
> > > > >>value greater than 500.
> > > > >>
> > > > >>Tomcat locks up completely without getting back to normal operations
> > > > >>after a while. No exception or error is reported in the logs,
it just
> > > > >>stops. All connections are refused after the lockup. Tomcat has
enough
> > > > >>memory (>1GB) assigned with the JVM options.
> > > > >>
> > > > >>If I use maxThreads="500", the server runs fine, but 500 is not
enough
> > > > >>for my project ;-(
> > > > >>
> > > > >>I tried to increase the stack size, but this doesn't help..
> > > > >>
> > > > >>The connector is defined as:
> > > > >>
> > > > >><Connector port="8888" maxHttpHeaderSize="8192" maxThreads="500"
> > > > >>   minSpareThreads="50" maxSpareThreads="150" enableLookups="false"
> > > > >>   redirectPort="8443" acceptCount="200" connectionTimeout="20000"
> > > > >>   disableUploadTimeout="true"/>
> > > > >>
> > > > >>If I change 500 to 700 or more, Tomcat locks up. Is this a Windows
> > > > >>problem?? 
> > > > >>
> > > > >>Hardware is not an issue, I think.. (dual Xeon 3,4GHz, 4GB)..
> > > > >>
> > > > >>Thanks,
> > > > >>Michael
> > > > >>
> > > > > 
> > > > > 
> > > > 
> > > > 
> > > 
> > > -- 
> > > David Delbecq
> > > Royal Meteorological Institute of Belgium
> > > 
> > > -
> > > Is there life after /sbin/halt -p?
> > > 
> > > ---------------------------------------------------------------------
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> > > 
> > 
> 
> -- 
> David Delbecq
> Royal Meteorological Institute of Belgium
> 
> -
> Is there life after /sbin/halt -p?
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: tomcat-user-unsubscribe@jakarta.apache.org
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> 

-- 
Michael Kleinhenz
tarent GmbH . Bahnhofstr. 13 . 53123 Bonn
fon +49 (228) / 52 67 5-0 . fax +49 (228) / 52 67 5-25

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