Re: Tomcat/Java starts using too much memory and not by the heap or non-heap memory

[Chuck Caldarale]

> On Jan 5, 2024, at 16:21, Brian Braun  wrote:
>> 
>> Tracking native memory usage can be tricky depending upon your
>> environment. I would only look into that if there were somethng very odd
>> going on, like your process memory space seems to be more than 50% taken
>> by non-java-heap memory.
>> 
> Well, actually that is my case. The heap memory (the 3 G1s) and non-heap
> memory (3 CodeHeaps + compressed class space + metaspace) together use just
> a few hundred MBs. I can see that using Tomcat Manager as well as the other
> monitoring tools. And the rest of the memory (about 1GB) is being used by
> the JVM but I don't know why or how, and that started 2 months ago. In your
> case you have just 20-25% extra memory used in a way that you don't
> understand, in my case it is about 200%.


The virtual map provided earlier doesn’t show any anomalies, but I really 
should have asked you to run the pmap utility on the active Tomcat process 
instead. The JVM heap that was active when you captured the data is this line:

c180-dda0 rw-p  00:00 0

which works out to 115,200 pages or almost 472 Mb. However, we don’t know how 
much of that virtual space was actually allocated in real memory. The pmap 
utility would have shown that, as seen below for Tomcat running with a 512M 
heap on my small Linux box. Having pmap output from your system, both before 
and after the high-memory event occurs, might provide some insight on what’s 
using up the real memory.

Are you using the Tomcat manager app to show memory information? This is a 
quick way to display both maximum and used amounts of the various JVM memory 
pools.

Below is the sample pmap output for my test system; the Kbytes and RSS columns 
are of primary interest, notably the 527232 and 55092 for the JVM heap at 
address e000. Finding the actual offender won’t be easy, but having 
both before and after views may help.

  - Chuck


26608:   /usr/lib64/jvm/java-11-openjdk-11/bin/java 
-Djava.util.logging.config.file=/home/chuck/Downloads/apache-tomcat-9.0.84/conf/logging.properties
 -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager 
-Djdk.tls.ephemeralDHKeySize=2048 
-Djava.protocol.handler.pkgs=org.apache.catalina.webresources 
-Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Xms512M -Xmx512M 
-Dignore.endorsed.dirs= -classpath 
/home/chuck/Downloads/apache-tomcat-9.0.84/bin/bootstrap.jar:/home/chuck/Downloads/apache-tomca
Address   Kbytes RSS PSS   DirtySwap Mode  Mapping
e000  527232   55092   55092   55092   0 rw-p-   [ anon ]
0001002e 1045632   0   0   0   0 ---p-   [ anon ]
561efff1e000   4   4   0   0   0 r--p- 
/usr/lib64/jvm/java-11-openjdk-11/bin/java
561efff1f000   4   4   0   0   0 r-xp- 
/usr/lib64/jvm/java-11-openjdk-11/bin/java
561efff2   4   4   0   0   0 r--p- 
/usr/lib64/jvm/java-11-openjdk-11/bin/java
561efff21000   4   4   4   4   0 r--p- 
/usr/lib64/jvm/java-11-openjdk-11/bin/java
561efff22000   4   4   4   4   0 rw-p- 
/usr/lib64/jvm/java-11-openjdk-11/bin/java
561f0095c000 264  68  68  68   0 rw-p-   [ anon ]
7f45d000 132  36  36  36   0 rw-p-   [ anon ]
7f45d0021000   65404   0   0   0   0 ---p-   [ anon ]
7f45d400 132  16  16  16   0 rw-p-   [ anon ]
7f45d4021000   65404   0   0   0   0 ---p-   [ anon ]
7f45d800 132  40  40  40   0 rw-p-   [ anon ]
7f45d8021000   65404   0   0   0   0 ---p-   [ anon ]
7f45dc00 132  84  84  84   0 rw-p-   [ anon ]
7f45dc021000   65404   0   0   0   0 ---p-   [ anon ]
7f45e000 132  16  16  16   0 rw-p-   [ anon ]
7f45e0021000   65404   0   0   0   0 ---p-   [ anon ]
7f45e400 132  16  16  16   0 rw-p-   [ anon ]
7f45e4021000   65404   0   0   0   0 ---p-   [ anon ]
7f45e8001340127612761276   0 rw-p-   [ anon ]
7f45e814f000   64196   0   0   0   0 ---p-   [ anon ]
7f45ec00 132  32  32  32   0 rw-p-   [ anon ]
7f45ec021000   65404   0   0   0   0 ---p-   [ anon ]
7f45f000 132  44  44  44   0 rw-p-   [ anon ]
7f45f0021000   65404   0   0   0   0 ---p-   [ anon ]
7f45f400 132  52  52  52   0 rw-p-   [ anon ]
7f45f4021000   65404   0   0   0   0 ---p-   [ anon ]
7f45f800 132  72  72  72   0 rw-p-   [ anon ]
7f45f8021000   65404   0   0   0   0 ---p-   [ anon ]
7f45fc00 132  52  52  52   0 rw-p-   [ anon 

Re: Tomcat/Java starts using too much memory and not by the heap or non-heap memory

[Brian Braun]

Hello Chirstopher,

First of all: thanks a lot for your responses!

On Wed, Jan 3, 2024 at 9:25 AM Christopher Schultz <
ch...@christopherschultz.net> wrote:

> Brian,
>
> On 12/30/23 15:42, Brian Braun wrote:
> > At the beginning, this was the problem: The OOM-killer (something that I
> > never knew existed) killing Tomcat unexpectedly and without any
> > explanation
>
> The explanation is always the same: some application requests memory
> from the kernel, which always grants the request(!). When the
> application tries to use that memory, the kernel scrambles to physically
> allocate the memory on-demand and, if all the memory is gone, it will
> pick a process and kill it.
>
>
Yes, that was happening to me until I set up the SWAP file and now at least
the Tomcat process is not being killed anymore.


> There are ways to prevent this from happening, but the best way to not
> to over-commit your memory.
>
> > Not knowing how much memory would I need to satisfy the JVM, and not
> > willing to migrate to more expensive Amazon instances just because I
> > don't know why this is happening. And not knowing if the memory
> > requirement would keep growing and growing and growing.
> It might. But if your symptom is Linux oom-killer and not JVM OOME, then
> the better technique is to *reduce* your heap space in the JVM.
>
> > Then I activated the SWAP file, and I discovered that this problem stops
> at
> > 1.5GB of memory used by the JVM. At least I am not getting more crashes
> > anymore. But I consider the SWAP file as a palliative and I really want
> to
> > know what is the root of this problem. If I don't, then maybe I should
> > consider another career. I don't enjoy giving up.
>
> Using a swap file is probably going to kill your performance. What
> happens if you make your heap smaller?
>
>
Yes, in fact the performance is suffering and that is why I don't consider
the swap file as a solution.
I have assigned to -Xmx both small amounts (as small as 300MB) and high
amounts (as high as 1GB) and the problem is still present (the Tomcat
process grows in memory usage up to 1.5GB combining real memory and swap
memory).
As I have explained in another email recently, I think that neither heap
usage nor non-heap usage are the problem. I have been monitoring them and
their requirements have always stayed low enough, so I could leave the -Xms
parameter with about 300-400 MB and that would be enough.
There is something else in the JVM that is using all that memory and I
still don't know what it is. And I think it doesn't care about the value I
give to -Xmx, it uses all the memory it wants. Doing what? I don't know.

> Yes, the memory used by the JVM started to grow suddenly one day, after
> > several years running fine. Since I had not made any changes to my app, I
> > really don't know the reason. And I really think this should not be
> > happening without an explanation.
> >
> > I don't have any Java OOME exceptions, so it is not that my objects don't
> > fit. Even if I supply 300MB to the -Xmx parameter. In fact, as I wrote, I
> > don't think the Heap and non-heap usage is the problem. I have been
> > inspecting those and their usage seems to be normal/modest and steady. I
> > can see that using the Tomcat Manager as well as several other tools (New
> > Relic, VisualVM, etc).
>
> Okay, so what you've done then is to allow a very large heap that you
> mostly don't need. If/when the heap grows a lot -- possibly suddenly --
> the JVM is lazy and just takes more heap space from the OS and
> ultimately you run out of main memory.
>
> The solution is to reduce the heap size.
>
>
Maybe I am not understanding your suggestion.
I have assigned to -Xmx both small amounts (as small as 300MB) and high
amounts (as high as 1GB) and the problem is still present. In fact the
problem started with a low amount for -Xmx.


> > Regarding the 1GB I am giving now to the -Xms parameter: I was giving
> just
> > a few hundreds and I already had the problem. Actually I think it is the
> > same if I give a few hundreds of MBs or 1GB, the JVM still starts using
> > more memory after 3-4 days of running until it takes 1.5GB. But during
> the
> > first 1-4 days it uses just a few hundred MBs.
> >
> > My app has been "static" as you say, but probably I have upgraded Tomcat
> > and/or Java recently. I don't really remember. Maybe one of those
> upgrades
> > brought this issue as a result. Actually, If I knew that one of those
> > upgrades causes this huge pike in memory consumption and there is no way
> to
> > avoid it, then I would accept it as a fact of life and move on. But
> since I
> > don't know, it really bugs me.
> >
> > I have the same amount of users and traffic as before. I also know how
> much
> > memory a session takes and it is fine.  I have also checked the HTTP(S)
> > requests to see if somehow I am getting any attempts to hack my instance
> > that could be the root of this problem. Yes, I get hacking attempts by
> > those bots all 

Re: OCSP Stapling Configuration and Tomcat 9

[Bhavesh Mistry]

Hi Chris,

Thanks for the update and confirming that we don't need a native connector
for OCSP stamping to work.   I have not followed any of the instructions
below. I am at the beginning of the journey trying to explore what changes
are needed to support OCSP stamping.  Again, thanks for your support and
reference. I will test it out based on the reference you provided. If I
need any help, I will kindly reach out again.



*Did you follow the instructions from the progress.com
 page concerningthe importing of your server's key
and certificate and the CA'sintermediate and root certs?*

Thanks,

Bhavesh

On Fri, Jan 5, 2024 at 11:07 AM Christopher Schultz <
ch...@christopherschultz.net> wrote:

> Bhavesh,
>
> On 1/5/24 12:57, Bhavesh Mistry wrote:
> > Hi All,
> >
> > According to Tomcat 9 Official documentation, only Tomcat NATIVE
> Connector
> > supports it.
> >
> https://tomcat.apache.org/tomcat-9.0-doc/ssl-howto.html#Using_OCSP_Certificates
> >
> > But this site claims
> >
> https://community.progress.com/s/article/PASOE-OCSP-Stapling-does-not-work
> > that it works with non-native connectors.   Please let me know if a
> > non-native connector works or not for OCSP Stamping.
> >
> > Here is the reference configuration:
> >
> >
> > - Update the *protocol *property and add the *sslImplementationName
> > *property
> > as follows:
> >
> >   > port="${psc.as.https.port}"
> > protocol="org.apache.coyote.http11.*Http11NioProtocol*"
> >
>  sslImplementationName="org.apache.tomcat.util.net.jsse.JSSEImplementation"
> >
> >
> > - Add the *-Djdk.tls.server.enableStatusRequestExtension=true* JVM
> > system property in the *\conf\jvm.properties* file to
> > enable OCSP Stapling support for the JVM.
> > - It is also recommended to add the
> -Djdk.tls.ephemeralDHKeySize=2048 JVM
> > parameter to the *\conf\jvm.properties* file to
> prevent
> > the use of weak Diffie-Hellman (DH) keys. For more information,
> please
> > refer to the following Oracle
>
> According to https://bz.apache.org/bugzilla/show_bug.cgi?id=56148 this
> is not complete for the APR connector. I do recall lots of conversation
> about this, and I thought it was working, but Mark is very diligent
> about updating bugs when they are complete, so it's unlikely he
> completed the work and then didn't close the bug.
>
> According to the conversation in that bug, NIO and NIO2 should work if
> you have a recent Java (9 or later ought to work) if you set that system
> property you have listed above.
>
> I have no idea what \conf\jvm.properties is for, but you
> should make absolutely sure that the system property is actually being
> set at JVM launch. You can write a simple servlet or JSP to inspect that
> to verify, or use something like jinfo to inspect a running process's
> system properties.
>
> Did you follow the instructions from the progress.com page concerning
> the importing of your server's key and certificate and the CA's
> intermediate and root certs?
>
> -chris
>
> -
> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
> For additional commands, e-mail: users-h...@tomcat.apache.org
>
>

Re: OCSP Stapling Configuration and Tomcat 9

[Christopher Schultz]

Bhavesh,

On 1/5/24 12:57, Bhavesh Mistry wrote:

Hi All,

According to Tomcat 9 Official documentation, only Tomcat NATIVE Connector
supports it.
https://tomcat.apache.org/tomcat-9.0-doc/ssl-howto.html#Using_OCSP_Certificates

But this site claims
https://community.progress.com/s/article/PASOE-OCSP-Stapling-does-not-work
that it works with non-native connectors.   Please let me know if a
non-native connector works or not for OCSP Stamping.

Here is the reference configuration:


- Update the *protocol *property and add the *sslImplementationName
*property
as follows:

 \conf\jvm.properties* file to
enable OCSP Stapling support for the JVM.
- It is also recommended to add the -Djdk.tls.ephemeralDHKeySize=2048 JVM
parameter to the *\conf\jvm.properties* file to prevent
the use of weak Diffie-Hellman (DH) keys. For more information, please
refer to the following Oracle


According to https://bz.apache.org/bugzilla/show_bug.cgi?id=56148 this 
is not complete for the APR connector. I do recall lots of conversation 
about this, and I thought it was working, but Mark is very diligent 
about updating bugs when they are complete, so it's unlikely he 
completed the work and then didn't close the bug.


According to the conversation in that bug, NIO and NIO2 should work if 
you have a recent Java (9 or later ought to work) if you set that system 
property you have listed above.


I have no idea what \conf\jvm.properties is for, but you 
should make absolutely sure that the system property is actually being 
set at JVM launch. You can write a simple servlet or JSP to inspect that 
to verify, or use something like jinfo to inspect a running process's 
system properties.


Did you follow the instructions from the progress.com page concerning 
the importing of your server's key and certificate and the CA's 
intermediate and root certs?


-chris

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OCSP Stapling Configuration and Tomcat 9

[Bhavesh Mistry]

Hi All,

According to Tomcat 9 Official documentation, only Tomcat NATIVE Connector
supports it.
https://tomcat.apache.org/tomcat-9.0-doc/ssl-howto.html#Using_OCSP_Certificates

But this site claims
https://community.progress.com/s/article/PASOE-OCSP-Stapling-does-not-work
that it works with non-native connectors.   Please let me know if a
non-native connector works or not for OCSP Stamping.

Here is the reference configuration:


   - Update the *protocol *property and add the *sslImplementationName
*property
   as follows:

\conf\jvm.properties* file to
   enable OCSP Stapling support for the JVM.
   - It is also recommended to add the -Djdk.tls.ephemeralDHKeySize=2048 JVM
   parameter to the *\conf\jvm.properties* file to prevent
   the use of weak Diffie-Hellman (DH) keys. For more information, please
   refer to the following Oracle

Thanks,

Bhavesh

Re: Posting questions

[Rob Sargent]

On 1/5/24 07:31, Jalaj Asher wrote:

Omkar,
2 questions
1. when you say processes what processes are you seeing being invoked and does 
it stop at 200 processes. May be a screen shot might help
2. does the tomcat have read write privilege on all its folders ? If not does 
giving those rights help ?



Do screen shots will make it through to the readers? Text from ps might 
be safer.

RE: Posting questions

[Jalaj Asher]

Omkar,
2 questions
1. when you say processes what processes are you seeing being invoked and does 
it stop at 200 processes. May be a screen shot might help
2. does the tomcat have read write privilege on all its folders ? If not does 
giving those rights help ?



-Original Message-
From: Vaidya, Omkar 
Sent: Friday, January 5, 2024 4:56 AM
To: users@tomcat.apache.org
Subject: Posting questions

Attention! - This email has originated from an External Source outside of 
eClinicalWorks. Always use caution when opening attachments, clicking links, or 
when responding to this email. If you feel this is a phishing scam, please use 
the Phish Alert Report button in Outlook.


Hi Team,



Tomcat Version - 9.0.62

Platform - Linux Platform





This is regarding like we have one customer issue where on Linux platform, we 
have configured our IOT-application (Thingworx), which is using Tomcat as a 
server.

So we are able to identify that even when we remove our application, Tomcat is 
creating a zombie (defunct) process, which is creating 200+ processes under the 
process table, which ultimately occupy all the OS resources and the application 
goes in a hung state. This issue is also reproducible on the Standalone Tomcat 
server also.

There are two scenarios mentioned below -

1.If this is relatable to Tomcat can you please suggest any article 
or documentation so that we can stop zombie process creation, if this is a 
known issue or there is only way to clear zombie (defunct) process from 
Processes table of linux.

2.Also, let us know if this is a Operating System specific issue 
like as it is reproducible only on Linux, So Linux os is the thing that creates 
the zombie (defunct) processes?

we are eagerly waiting for the response.



Thanks,

Omkar Vaidya.


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Re: Regarding Tomcat is creating the zombie processes

[Olaf Kock]

On 05.01.24 14:17, Simon Matter wrote:

You will need to provide more details.

A default Tomcat install does not create parent and child processes so
zombie processes cannot occur.


Often, Java-Threads look like child processes in Linux tools.

I'm assuming that the application creates non-daemon threads, that don't 
terminate when they should.


Tomcat itself only creates connector-related threads according to the 
declaration in server.xml, and optionally database pools (or similar), 
also as declared. Other threads /might/ be created by the (custom) 
application that you deploy, and /they/ might prevent tomcat from ever 
exiting cleanly.


My working hypothesis: The reason for the described behavior is 100% on 
the application side, not at all with Tomcat.


As you state exhaustion of system resources: Depending on your use case, 
you might need to make more system resources available - I've seen cases 
where a server ran out of file-descriptors (or similar - this is very 
vague memory).



I'll also note that zombie process do not consume system resources
(apart from a process ID).

Please provide the steps you used to recreate this issue in a clean
installation of a standalone Tomcat instance.

Mark


As an easy start you could provide us with the Tomcat related process tree
and detailed description of how the lifecycle of Tomcat is managed.

I'd recommend analyzing at a thread dump, created before zombification, 
to look at the nature of all of the threads that are running in your 
system before it goes down - or rather before it doesn't go down.


Olaf

Re: Regarding Tomcat is creating the zombie processes

[Simon Matter]

> You will need to provide more details.
>
> A default Tomcat install does not create parent and child processes so
> zombie processes cannot occur.
>
> I'll also note that zombie process do not consume system resources
> (apart from a process ID).
>
> Please provide the steps you used to recreate this issue in a clean
> installation of a standalone Tomcat instance.
>
> Mark
>

As an easy start you could provide us with the Tomcat related process tree
and detailed description of how the lifecycle of Tomcat is managed.

Regards,
Simon


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Re: Regarding Tomcat is creating the zombie processes

[Mark Thomas]

You will need to provide more details.

A default Tomcat install does not create parent and child processes so 
zombie processes cannot occur.


I'll also note that zombie process do not consume system resources 
(apart from a process ID).


Please provide the steps you used to recreate this issue in a clean 
installation of a standalone Tomcat instance.


Mark


On 05/01/2024 09:48, Vaidya, Omkar wrote:

Adding information -
Tomcat Version - 9.0.62
Platform - Linux Platform


From: Vaidya, Omkar 
Sent: Friday, January 5, 2024 3:15 PM
To: users@tomcat.apache.org
Cc: Shriwardhankar, Varun 
Subject: Regarding Tomcat is creating the zombie processes

Hi Team,

This is regarding like we have one customer issue where on Linux platform, we 
have configured our IOT-application (Thingworx), which is using Tomcat as a 
server.
So we are able to identify that even when we remove our application, Tomcat is 
creating a zombie (defunct) process, which is creating 200+ processes under the 
process table, which ultimately occupy all the OS resources and the application 
goes in a hung state. This issue is also reproducible on the Standalone Tomcat 
server also.
There are two scenarios mentioned below -
1.If this is relatable to Tomcat can you please suggest any article 
or documentation so that we can stop zombie process creation, if this is a 
known issue or there is only way to clear zombie (defunct) process from 
Processes table of linux.
2.Also, let us know if this is a Operating System specific issue 
like as it is reproducible only on Linux, So Linux os is the thing that creates 
the zombie (defunct) processes?
we are eagerly waiting for the response.

Thanks,
Omkar Vaidya.




-
To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
For additional commands, e-mail: users-h...@tomcat.apache.org

Posting questions

[Vaidya, Omkar]

Hi Team,



Tomcat Version - 9.0.62

Platform - Linux Platform





This is regarding like we have one customer issue where on Linux platform, we 
have configured our IOT-application (Thingworx), which is using Tomcat as a 
server.

So we are able to identify that even when we remove our application, Tomcat is 
creating a zombie (defunct) process, which is creating 200+ processes under the 
process table, which ultimately occupy all the OS resources and the application 
goes in a hung state. This issue is also reproducible on the Standalone Tomcat 
server also.

There are two scenarios mentioned below -

1.If this is relatable to Tomcat can you please suggest any article 
or documentation so that we can stop zombie process creation, if this is a 
known issue or there is only way to clear zombie (defunct) process from 
Processes table of linux.

2.Also, let us know if this is a Operating System specific issue 
like as it is reproducible only on Linux, So Linux os is the thing that creates 
the zombie (defunct) processes?

we are eagerly waiting for the response.



Thanks,

Omkar Vaidya.

RE: Regarding Tomcat is creating the zombie processes

[Vaidya, Omkar]

Adding information -
Tomcat Version - 9.0.62
Platform - Linux Platform


From: Vaidya, Omkar 
Sent: Friday, January 5, 2024 3:15 PM
To: users@tomcat.apache.org
Cc: Shriwardhankar, Varun 
Subject: Regarding Tomcat is creating the zombie processes

Hi Team,

This is regarding like we have one customer issue where on Linux platform, we 
have configured our IOT-application (Thingworx), which is using Tomcat as a 
server.
So we are able to identify that even when we remove our application, Tomcat is 
creating a zombie (defunct) process, which is creating 200+ processes under the 
process table, which ultimately occupy all the OS resources and the application 
goes in a hung state. This issue is also reproducible on the Standalone Tomcat 
server also.
There are two scenarios mentioned below -
1.If this is relatable to Tomcat can you please suggest any article 
or documentation so that we can stop zombie process creation, if this is a 
known issue or there is only way to clear zombie (defunct) process from 
Processes table of linux.
2.Also, let us know if this is a Operating System specific issue 
like as it is reproducible only on Linux, So Linux os is the thing that creates 
the zombie (defunct) processes?
we are eagerly waiting for the response.

Thanks,
Omkar Vaidya.

Regarding Tomcat is creating the zombie processes

[Vaidya, Omkar]

Hi Team,

This is regarding like we have one customer issue where on Linux platform, we 
have configured our IOT-application (Thingworx), which is using Tomcat as a 
server.
So we are able to identify that even when we remove our application, Tomcat is 
creating a zombie (defunct) process, which is creating 200+ processes under the 
process table, which ultimately occupy all the OS resources and the application 
goes in a hung state. This issue is also reproducible on the Standalone Tomcat 
server also.
There are two scenarios mentioned below -
1.If this is relatable to Tomcat can you please suggest any article 
or documentation so that we can stop zombie process creation, if this is a 
known issue or there is only way to clear zombie (defunct) process from 
Processes table of linux.
2.Also, let us know if this is a Operating System specific issue 
like as it is reproducible only on Linux, So Linux os is the thing that creates 
the zombie (defunct) processes?
we are eagerly waiting for the response.

Thanks,
Omkar Vaidya.


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