-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Daniel,
On 10/23/12 4:12 PM, Daniel Barcellos wrote: > Imagine this simple examplo... we used to develop app for Oracle > forms that runs over a oracle application server. If you need to > install it you should obey a big list of requirement so that every > thing under its control will run ok. Now we need to use and deploy > software over Tomcat that is basically a free server. Where can I > find those requirements? Tomcat by itself (well, with the JVM) can run in about 16MiB of Java heap. Your webapp will probably need a *whole* lot more than that. Tomcat is lean and mean. OAS is a beast that has higher minimal requirements, but I suspect that OAS all by itself can run in maybe 32MiB or 40MiB. The reason they tell you that you need 32GiB of heap space is because they want your app to work pretty much no matter what. Realistically, only you can determine what your requirements are. Start by giving the JVM plenty of heap space. Let's say 1GiB (if you have it) on a test bed. Then, deploy your webapp, force a few GCs (use jconsole or something else that allows you to do that) then check the memory usage: that's your baseline. You cannot possibly go below that and support even 0 users. Then, login a single user and go through a typical workflow. Repeat the GC/heap dance from above and see what the requirements are for a single user. Then try 10 users. Then 20 users. You can even graph them if you want to get fancy (which I recommend). I also recommend using a tool like JMeter to act as users. This will give you something repeatable and scalable (from a /load/ point of view). You might still be wrong about the heap space, because you may have huge transient requirements during a single transaction (for instance, you need to build an in-memory image, plot stuff against it, compress the image, etc.). You'll need to load-test your webapp in a test bed: that's the only way you can really know your requirements. The CPU speed is more difficult to pinpoint because realistically, any CPU will do, right? It's just a question of how long it takes to do stuff. So, you have to do all of the above (1 user, 10 users, 100 users) working constantly and checking the response time to see if it meets your targets. For instance, some people require that their response times are less than 500ms. For you, that might be more like 3000ms. You may have different targets for different transactions: choosing a chart template might need to be within 500ms but it's okay if the actual chart generation takes 10s. In case you aren't realizing it, yet: nobody can tell you what your own requirements are: you have to go figure them out yourself. If it makes you feel better, I can tell you what you need and I'm sure you'll be happy with the performance. Here goes: 1 IBM BladeCenter Chassis 4 IBM BladeCenter HSxx (you get to choose which ones) (You'll want a chassis with at least 8 blade slots: you'll need room to grow) Go for 1TiB per blade: you'll thank me later. You're definitely going to need a bank of SAS disks. Don't bother with elaborate RAID rigs or anything like that: just mirror everything because you don't want to waste time waiting for any RAID re-syncing. Or you could just fire the whole thing up on a laptop and beat the hell out of it. Your choice. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Mozilla - http://www.enigmail.net/ iEYEARECAAYFAlCHOHIACgkQ9CaO5/Lv0PA0hQCfeXBZPLpsaQl9uvLI2QKGQcwA 3NMAoLnjdE1dzgLwCedtMYwoPc12q7Pj =LdQW -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
