On 16.08.2017 15:34, Fady Haikal wrote:
Dear Team,
I'm facing an issue that tomcat from task manager is consuming around 60 GB of
memory
while from Oracle Java Mission Control is showing maximum 10 GB (Attached
screenshots),
and from time to time the server hang due to insufficent memory.
can you please advise why the above is showing like that? and why the memory of
the server
is not reducing?
Tomcat Version: 8.0.30
JDK: 1.7.0_67
Maybe one preliminary response here, just to orient your further thinking and analysis, is
that Tomcat itself will never use 60 GB of memory, nor even 10 GB of memory, nor even 1 GB
of memory. Properly configured, and with one basic and correct webapp, Tomcat would
certainly use much less than 1 GB.
What /may/ be using more memory is :
- parameters used when starting the Java JVM which runs Tomcat, related to the size of the
Java Heap etc.
- and then, more likely than not, /the web applications/ which you are running
within Tomcat
As to your second question (why Java's OS memory usage is not decreasing), maybe have a
look here :
http://www.stefankrause.net/wp/?p=14
and/or here :
https://coderanch.com/t/609676/java/Unused-java-memory-released-OS
and a number of other similar responses on the WWW.
Summary :
It looks like being an area of some uncertainty and discussion on the WWW, but the general
consensus seems to be that once Java has obtained some additional memory from the OS, it
never (or rarely) releases it, until the Java process itself exits.
Note that this is /Java/, not Tomcat-specific.
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