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From André Warnier ...@ice-sa.com>
Subject Re: very slow class loading on initial JSP/servlet request after restart
Date Sat, 21 Feb 2009 21:05:44 GMT
A summary so far :
- the problem is : on one certain machine, when deploying any JSP which 
imports a certain self-made library of classes, that JSP takes an 
inordinate amount of time (one minute or more) to compile for a 5-line JSP
- after compilation, the JSP in question responds totally normally to 
requests
- there are no errors in the Tomcat logs.  The logs show only the 
inordinate amount of time needed to load the application, when the 
offending library is included.
- the issue appears only on that particular machine, which is a modern 
and fast machine, dual quad-core Intel Xeon E5310 CPUs, with a 4-disk 
Raid array.  The same JSP and library on any other of 3 machines using 
the same JVM and Tomcat, does not exhibit the same problem
- the disk array was checked for problems using various means, and does 
not exhibit any.  The RAM was similarly checked.
- the issue persists if the JSP is copied under another name on the same 
machine
- the issue persists if the whole webapp containing that JSP is copied 
to a new webapp name on the same machine (and thus occupying a different 
disk and memory area)
- the issue disappears if said self-made library is no longer imported 
in the JSP; it reappears if the library is imported again
- the issue persists if the imported library is moved from 
webapp/WEB-INF/lib to the Tomcat common lib location and vice-versa
- the issue persists despite changing the JVM version and/or Tomcat version
- the issue does not appear when importing the same self-made library in 
a separate stand-alone Java program and compiling/running that program 
on the same machine (?) (was that the whole library, or just a 
File.exists() test ?)
- during the compilation of the bewitched JSP, the machine on which the 
inordinate delay occurs does not exhibit any remarkably high CPU, memory 
  or disk usage
- the bewitching library of which it is question does not make evident 
references to external network resources whose unavailability or slow 
access could explain the compilation delay
- the affected system is not near any known source of Alpha particles, 
nor near a reindeer farm, nor in the proximity of any significant 
quantity of chocolate or other dark matter
- other applications on the striken machine work fine and do not exhibit 
the above symptoms
- the machine in question does not activate Java's security manager (nor 
do the other non-affected machines)


Suggestions of the day :

1.
under the assumption that the library in question does not contain 
hundreds of classes, and that the problem occurs during compilation, so 
that an error during execution of the JSP would not matter..

Start removing (commenting out) the content of each class one by one and 
test, until the specific class causing the issue is found.

2.
turn off 1,2,3,4,5,6,7 of the machine cores and see if it changes the 
symptoms

3.
I have a currently unused machine standing here, which in a spirit of 
camaraderie and assistance I would offer to exchange for the affected 
machine.  It's not a quad-core or anything like that, but to my 
knowledge when it was last powered on a couple of years ago, it did not 
exhibit that kind of problem.


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