Tomcat Questions?

  • AAI-Tech
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Post 3+ Months Ago

I have a couple of questions I need a hand with and would appreciate any help you guys could give
(1) How do you set memory heap of Tomcat installed on your machine?


(2) I've been having problem with my database lately, and I think that the following errors have something to do with this.

Error message 1:

"Cannot initialize InnoDB as 'innodb_data_file_path' is not set. If you do not want to use transactional InnoDB tables, add a line skip-innodb to the [mysqld] section of init parameters in your my.cnf or my.ini. If you want to use InnoDB tables, add to the [mysqld] section, for example,

innodb_data_file_path = ibdata1:10M:autoextend

But to get good performance you should adjust for your hardware the InnoDB startup options listed in section 2 at

http://www.innodb.com/ibman.html"

q1.1. What does this really mean?

q1.2. What can I do to resolve this problem?

q1.3. Can this cause a serious problem like database lock up?

Error message 2:

lock: 1234abc: (1234abc is apparently some kind of reference number)

q2.1. Is this a bad sign?

q2.2. If so, what can I do to not let this happen?
  • Daemonguy
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Post 3+ Months Ago

1. (Keep in mind, you should set the max memory heap size far below that of what you actually have in the machine. ) The syntax is '-server -Xmx<memory_size><m, for megabytes; g, for gigabytes>'.
As an example, to see 400M the syntax would be -Xmx400m.
In linux place it in the CATALINA_OPTS environment variable. For example: "-server -Xmx400m".

2.1.1: It means you should follow those directions and add that line to your my.cnf or my.ini file. As for providing better performance through tuning, I agree with the error message; you should read Section 2 as described.
This is actually, one of the most informative error messages I have ever seen. Hat's off to the innodb crew.
As an addendum, you do understand that innodb is used for crash recovery and rollback, as well as some Oracle-style row locking and non-locking read statements.

2.1.2: Again, follow the instructions. They really are quite clear.

2.1.3: Will it work? Yes. Is it healthy? No. Could is screw up royally later on since innodb params are not met? Yes. Would I fix it? Hell yes.

2.2.1: I have never known error messages to be considered a "good thing", unless of course they lead you to resolve an issue. :)
Could you provide more information about this error? When do you see it? What is it in reference to?

2.2.2: See previous.

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