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From "Filip Hanik" <devli...@hanik.com>
Subject RE: Found it - WAS: Memory leak
Date Thu, 15 Jan 2004 04:02:57 GMT
+0 (would have been +1 but I don't know that I have extra cycles for dev
right now)

I agree on that. The current problem keeps it from being production stable.

With the bug fixed, I am able to run 1000 concurrent users (3 sec sleep
between each request) again 4 clustered tomcat instances on two mediocre
machines. The average response time is about 2 seconds, the cpu is around
40% on each machine, and most important, the memory stays constant. These
tests used to crap out on me after a little while, but now it keeps going
and going. Unfortunately I am saturating my little home network :)

Filip

-----Original Message-----
From: Bill Barker [mailto:wbarker@wilshire.com]
Sent: Wednesday, January 14, 2004 8:07 PM
To: Tomcat Developers List
Subject: Re: Found it - WAS: Memory leak


I'd be in favor of just dropping RequestInfo and RequestGroupInfo altogether
(and provide RequestListener commented out in web.xml that does the same
thing).  Then people that want this can still get Request stats via JMX
(which I might use on a development site, but never on a production site).
And as a bonus, we get to ship an example of a RequestListener :).

Removing isn't hard (I've just done it for my downloaded version of 5.0.17).
The original code isn't very careful about what operations are atomic, so a
replacement Listener that's as good as RequestGroupInfo isn't hard to do
either :).

----- Original Message -----
From: "Filip Hanik" <devlists@hanik.com>
To: "Tomcat Developers List" <tomcat-dev@jakarta.apache.org>
Sent: Wednesday, January 14, 2004 6:47 PM
Subject: Found it - WAS: Memory leak


> Ok, I think I nailed it.
> There is a memory leak in Tomcat 5. I downloaded a trial of JProbe (they
> should provide free licenses for open source! :)
>
> There is a class called o.a.coyote.RequestGroupInfo.java, in that class
> there is a method called addRequestProcessor.
>
> This method stores a reference to a RequestInfo object in an ArrayList,
the
> RequestInfo object has a reference to a Request object and that eventually
> holds the reference to a MessageBytes/ByteChunk.
>
> The nr of instances of ByteChunk and CharChunk keep growing and they never
> get garbage collected.
> To validate my thoughts, I commented out the line
>
> public void addRequestProcessor( RequestInfo rp ) {
>     //processor.add( rp );
> }
>
> in RequestGroupInfo.java and now the instance count for ByteChunk stay
> constant.
>
> I have a feeling that the actual solution is a little bit deeper down,
right
> now I am eager on getting the clustering to perform the way I want, so if
> someone wants to take this on be my guest and let me know. If I don't hear
> from anyone, I will commit a solution to this next week.
>
>
> Filip
>
> -----Original Message-----
> From: Filip Hanik [mailto:devlists@hanik.com]
> Sent: Wednesday, January 14, 2004 5:22 PM
> To: Tomcat Developers List
> Subject: RE: Memory leak- yeah I know
>
>
> RE: Memory leak- yeah I knowhi Michael, thanks for your info. I will look
> into that as well and set those settings
> The thing I am investigating right now is if the fact that we are
> registering a lot of things with JMX causes some references to never be
> released.
>
> more info to follow.
> Filip
>   -----Original Message-----
>   From: Michael Yates [mailto:yatesmi@nortelnetworks.com]
>   Sent: Wednesday, January 14, 2004 4:43 PM
>   To: Tomcat Developers List
>   Subject: RE: Memory leak- yeah I know
>
>
>   Filip,
>   I spent some time a while back trying to get some reproducibility into
> memory use in Tomcat (4.1.24)
>   I found that even sitting idle tomcats memory use would increase.
>
>   Here is my original mail to the tomcat-dev mailing list
>   <<4.1.24 secure connector throws a LOT of garbage>>
>
>   After I did some more investigations and figured out a fix the following
> bug was raised
>   http://nagoya.apache.org/bugzilla/show_bug.cgi?id=19264
>
>   To reduce the amount of garbage thrown by tomcat I would recommend two
> things, doing these might help you track down other memory issues.
>
>   1 - Use -Xmx<someValue>m -Xms<someValue>m.
>   The above sizes the heap to whatever value you put in there (note the
> value is megabytes). I found (at least on the Solaris JVM) that sizing the
> heap and making the min and max heap sizes the same not only sped up start
> up but also made the garbage collector behave much better.
>
>   2- Set the serverSoTimeout value to 0 in the connector configuration in
> your server configuration file. This will prevent the sever socket timing
> out. Which DOES throw garbage, and if it is a secure connector you are
using
> it throws SO much garbage that the garbage collector can not keep up too
> well.
>
>   Using just number tip 1 above (as the fix to the bug above wasn't in
> Tomcat 4.1.x before we needed to go into production. We managed to run at
> something like 100 TPS for 48 hours with no falling over and no net
increase
> in memory usage.
>
>   If you need any more information on the above let me know.
>
>   Michael Yates
>   Software Engineer, Location Center
>   Nortel Networks Wollongong, Australia.
>
>
>
>
>   -----Original Message-----
>   From: Filip Hanik [mailto:devlists@hanik.com]
>   Sent: Thursday, 15 January 2004 11:09 AM
>   To: Tomcat Developers List
>   Subject: RE: Memory leak- yeah I know
>
>
>
>   Remy, absolutely no intentions of being sarcastic :), if there isn't a
> leak, that is great, if there is, will fix it.
>
>   I'm trying to figure it out, I didn't ask anyone else to spend time on
it,
> or even read my email. but if anyone is doing work on this lets work on it
> together.
>
>   just got jprobe up and running, once I have ran a few tests, I will
> experiment with the garbage collection, the memory is slowly growing, its
> been running for an hour.
>
>   Filip
>
>   -----Original Message-----
>   From: Remy Maucherat [mailto:remm@apache.org]
>   Sent: Wednesday, January 14, 2004 3:08 PM
>   To: Tomcat Developers List
>   Subject: Re: Memory leak- yeah I know
>
>
>
>   Filip Hanik wrote:
>
>   > Ok, I know that these emails are usually dismissed with the words:
>   > "Gets us some proof from a profiler", and I will...gimme some time, in
>   > the meanwhile, if anyone else wants to play with it.
>   >
>   > well the story is that during heavy load tests of the session
>   replication my
>   > system my VMs always run out of memory.
>   > What am I doing different than others, well, during my load tests I am
>   > not using keep alive connections to achieve true round robin. I'm
>   doing this by
>   > setting method.setHttp11(false) in the Http client.
>   >
>   > Running the test (attached, instructions below) I am hitting
>   > http://localhost:8080/index.jsp (home page) and watching the
>   memory grow and
>   > grow and grow.
>   >
>   > I am using a profiler and having somewhat of a hard time reading
>   the output.
>   > I am gonna download a trial of jprobe, see how that works out for
>   > me... I will be back with results from that.
>   >
>   > in the meantime, for those who want to see their memory grow here are
>   > the instructions
>   >
>   > My env:
>   > Machine: PIII 1.6Ghz, 512MB Ram
>   > OS: Redhat 8
>   > VM: Sun JDK 1.4.2_02 (build 1.4.2_02-b03)
>   >
>   > Instructions:
>   > download the attached client.jar
>   >
>   > execute:
>   > java -cp testclient.jar;commons-httpclient.jar;commons-logging.jar
>   > org.apache.catalina.cluster.test.client.MemTestClient http
>   > ://192.168.0.103:7080/index.jsp 100 100000 1000 false (exchange ; for
>   > : on
>   > unix)
>   >
>   > Watching the memory grow using Top, although it shouldn't increase at
>   > all.
>
>   There's ab for that kind of stuff, you know ... No need to waste your
time
> writing some new stuff. Your tone is a bit sarcastic, I think. I'm eagerly
> awaiting your "proofs" ;-)
>
>   Rémy
>
>
>
>
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