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From Thomas Freitag <tho...@freit.ag>
Subject Re: Tomcat 7 Per Instance Memory Footprint in Hello World App.
Date Tue, 15 Mar 2011 06:43:56 GMT
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Hi Noah,

On 03/15/2011 06:25 AM, Noah Cutler wrote:
> can find nothing on the net re: this apparently basic question.
> 
> Given a simple hello world "app", what is the @memory footprint per
> instance in Tomcat 7?
> 
> Just trying to assess options visa vi single instance + multiple virtual
> hosts vs. multiple instance single host (preferred option as each client
> app is isolated from the other).

There is a simple answer from the Java Heap point of view, a stock
Apache Tomcat 7.0.11 (running in Oracle JVM 1.6.0_24) around 3.5MB in
Heap, 11MB in Permanent Generation after startup (see garbage collection
log):

Heap after GC invocations=5 (full 2):
 PSYoungGen      total 18752K, used 0K [0x9ea50000, 0x9ff30000, 0xb38f0000)
  eden space 16128K, 0% used [0x9ea50000,0x9ea50000,0x9fa10000)
  from space 2624K, 0% used [0x9fa10000,0x9fa10000,0x9fca0000)
  to   space 2624K, 0% used [0x9fca0000,0x9fca0000,0x9ff30000)
 PSOldGen        total 42880K, used 3417K [0x74cf0000, 0x776d0000,
0x9ea50000)
  object space 42880K, 7% used [0x74cf0000,0x75046520,0x776d0000)
 PSPermGen       total 18176K, used 10916K [0x70cf0000, 0x71eb0000,
0x74cf0000)
  object space 18176K, 60% used [0x70cf0000,0x71799068,0x71eb0000)

- From the system (32bit Linux in my test case) point of view, my test
with pmap gave me a total of 1191428K (~ 1.1GB). This includes shared
libraries, Heap, Perm, code cache and other native memory (stacks,
buffers etc), thus some of this can be used by other JVM instances...

To cut it short: Tomcats memory footprint is very small, that shouldn't
be a problem for you. The JVM memory footprint depends on JVM version,
operating system and might be a problem if you run many JVM instances.
Test it in your system...

Regards,
- -- 
Thomas Freitag
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