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From David kerber <dcker...@verizon.net>
Subject Re: Tomcat memory
Date Mon, 22 Feb 2016 12:45:56 GMT
On 2/22/2016 7:02 AM, Gokul.Baskaran wrote:
> The answer I expected is the JVM grows as much as to the available system memory of there
are m min and max set.

But if you go back and read what others have posted, you will find that 
that is not the case.  Just because that's what you expect, does not 
mean that is what is actually going to happen.


>
> -Gokul
>
> Sent from iPhone
>
>> On Feb 22, 2016, at 2:43 AM, André Warnier (tomcat) <aw@ice-sa.com> wrote:
>>
>>> On 22.02.2016 03:44, Gokul.Baskaran wrote:
>>> Thanks again, to make things clear. When I meant default, what is the default
min and max that is given to an application if there nothing defined in the JVM ?
>>
>> In how many different ways do you need to be told this ?
>> Re-read the previous answers that you already received.  All the information is there.
>>
>>> In my case, the Tomcat is running on windows and I don't have setenv.bat or sentenv.sh
or even catalina.bat and catalina.conf does not have the OPT config for min and max. HTH
>>>
>>> Thank you
>>>
>>> -Gokul
>>>
>>>
>>> -----Original Message-----
>>> From: Olaf Kock [mailto:tomcat@olafkock.de]
>>> Sent: Sunday, February 21, 2016 3:04 PM
>>> To: Tomcat Users List <users@tomcat.apache.org>
>>> Subject: Re: Tomcat memory
>>>
>>> grep mx bin/* found only settings in setenv.sh in my installation - this lets
me state that there are no defaults: setenv.sh is not contained in the distribution but will
be read in case it's found in the file system.
>>> Thus there's no tomcat default that I'm aware of. Anybody who distributes tomcat
with a setenv.sh might have a sensible default for their embedded application, but the raw
distribution AFAIK has none.
>>>
>>> Safe assumption should be: Whatever the JVM thinks is appropriate is the default.
>>>
>>> Create a setenv.sh or setenv.bat and set CATALINA_OPTS to the desired value,
e.g. "-Xms 2048m -Xmx2048m" (but there will probably be more settings, e.g. for tuning the
garbage collector...
>>>
>>> (apologies in case this goes out after the problem has long been solved:
>>> I'm in a hotel that blocks SMTP and have to find a way to send mail from
>>> here)
>>>
>>> Olaf
>>>
>>>> Am 21.02.2016 um 18:23 schrieb Gokul.Baskaran:
>>>> Question was for Java 7
>>>>
>>>> It is a Tomcat / Application question as well, as memory default can be configured
in the application config.
>>>>
>>>> I totally agree that the best practice is to set the Xms and -Xmx. As am
going to change the config, I would curious to know if the tomcat ui or the catalina does
not have a Xms and -Xmx, would it default to 400MB? I read this in another forum.
>>>>
>>>> -Gokul
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Olaf Kock [mailto:tomcat@olafkock.de]
>>>> Sent: Sunday, February 21, 2016 3:14 AM
>>>> To: Tomcat Users List <users@tomcat.apache.org>
>>>> Subject: Re: Tomcat memory
>>>>
>>>> This is rather a Java than a tomcat question:
>>>>
>>>> The JVM allocates memory based on whatever default your current JVM
>>>> version decides (you don't mention what version of Java you're on)
>>>>
>>>>  From a text on
>>>> http://docs.oracle.com/javase/7/docs/technotes/guides/vm/gc-ergonomics
>>>> .html
>>>> that's linked from my Java's manpage:
>>>>
>>>>      *initial heap size*
>>>>
>>>>          Larger of 1/64th of the machine's physical memory on the machine
>>>>          or some reasonable minimum. Before J2SE 5.0, the default initial
>>>>          heap size was a reasonable minimum, which varies by platform.
>>>>          You can override this default using the |-Xms| command-line option.
>>>>
>>>>      *maximum heap size*
>>>>
>>>>          Smaller of 1/4th of the physical memory or 1GB. Before J2SE 5.0,
>>>>          the default maximum heap size was 64MB. You can override this
>>>>          default using the |-Xmx| command-line option.
>>>>
>>>>      *Note:* The boundaries and fractions given for the heap size are
>>>>      correct for J2SE 5.0. They are likely to be different in subsequent
>>>>      releases as computers get more powerful.
>>>>
>>>> Note that this is from JavaSE7 and even mentions 5 - with more power there
comes more initial and maximum memory defaults.
>>>>
>>>> I'm not aware of the actual development of the default memory - mostly
>>>> because I consider it good practice to know what an application uses
>>>> and provide it explicitly, rather than relying on defaults. (and
>>>> frankly, on the applications that I see, the default typically is not
>>>> even enough - let alone a good basis for tuning)
>>>>
>>>> While we're at it: For production systems I consider it good practice to
set -Xms and -Xmx to the same value. Reason: If you don't have enough memory available, you
want to know this when the process starts, not days later when it tries to allocate "the rest"
- typically sunday night at 3am.
>>>>
>>>> Olaf
>>>>
>>>>> Am 21.02.2016 um 03:39 schrieb Gokul.Baskaran:
>>>>> Hi,
>>>>>
>>>>> I am currently running tomcat 7 in Windows 2012.
>>>>>
>>>>> The current JVM Heap memory parameters are set to empty, does the JVM
Heap memory utilize the entire memory of the OS or does it default to a specific memory number?
>>>>>
>>>>> Thank you
>>>>> -Gokul
>>>>
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>>>
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>>>
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>>
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>>
>
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