Run_OYSTER_with_Extra_Memory

The OYSTER system was designed to perform all of its processing in Random Access Memory (RAM). This decision was made for various reasons but mainly to provide a system that can process large quantities of records very quickly. When disk I/O is removed and the system relies strictly on RAM for its work space, the processing can be sped up significantly.

Since OYSTER is written in Java, there are limitations on the amount of memory that is allocated by default. The default memory allocation for Java is 64 megabytes. This is enough space to process smaller amounts of records but you will eventually run out of memory as you process more and more records into a Knowledge Base.

Java offers 2 parameters that allow the user to control the amount of memory (called a heap in Java) to be allocated.

• -Xms

   o    This argument allows a user to define the initial size of them memory to be allocated.
   o    Defaults to 2MB

• -Xmx

   o    This argument allows a user to define the maximum memory that can be used during the Java run.

               NOTE: on Windows based 32-bit computers, the maximum memory allowed to be allocated by Java is 2048MB (2GB). This limitation does not exist in 64-bit systems or in UNIX.

   o    Defaults to 64MB

NOTE: When setting the Java memory size, the memory argument should be specified using one of the letters 'm' or 'M' for MB, or 'g' or 'G' for GB. 'MB' or 'GB' will not work.

These parameters are added to the java -jar Oyster.jar command ran from the command prompt or stored in a run script.

A finished command that allocates 64MB of memory for the initial run with a maximum of 2GB of memory would be: java –Xms64M –Xmx2G -jar Oyster.jar

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