Multithreading - Downstream Impacts

Multi threaded model will in most of the cases give better performance for batch applications. I would look at the below mentioned points along with the reengineering of the application code.

• Processing Power – There should be enough CPU power available in the machine.
• Memory – Since all threads will be working in parallel, the amount of memory used also will be considerably high. This can be however be reduced by not placing too many objects in JVM. However, the amount of memory required will be proportional to the number of threads in the application.
• Network Load – If the application is having network interactions like Database queries, FTP etc, the network load also will be high. In some cases, it would be solved by adding GBit connections between servers communicating. In most of the cases, the normal NIC’s itself can process the load.
• Disk Speed – If the application has lot of File processing, the disk accesses also need to be tuned. It would be better to read the files from SAN rather than NAS as the disk response time is better on SAN (my experience).
• Database Setup – If there is lot of database interactions, the database also should be made aware of such a change in the application. The load on the database will increase as there will be multiple threads that will try to fetch data from database. Most probably, it will end up increasing the database parameters to accept more loads.
• GC processing – The GC tuning should be performed. Since many threads are working in parallel, the amount of garbage created also will be high. An effective tune up of GC is required, without which, application will end up in OutofMemory Error. You can consider Parallel GC but ensure that the number of GC threads is mentioned.
• Synchronization – Objects that are created in JVM scope should be accessed with proper synchronization. If this is not worked out properly, it can cause dreaded issues like data corruption, deadlocks etc…