Joaquín Garzón

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As multiple versions of OpenText Output Transformation Server (OTS) can be installed at any given time, you can use the <OTS_home>\settings\startup.properties file to control which version is used upon starting the application. This file also gives us the option to set the maximum and minumum heap memory used by OTS Designer or Engine.

Java Virtual Machine’s -Xms and -Xmx parameters

The -Xms and -Xmx parameters are used to control the initial and maximum heap size allocated to the Java Virtual Machine (JVM). This is the amount of memory in bytes that will be used for creating and storing objects. Values for these parameters can be specified as bytes or in the following larger units:

  • k for kilobytes (e.g. –Xms104k)
  • m for megabytes (e.g. –Xms512m)
  • g for gigabytes (e.g. –Xms4g)

The value specified in -Xms will be allocated to the heap when the program starts. For example, -Xms512m will allocate 512 megabytes to the heap. The heap is not a fixed size: if more memory is needed, it can grow, up to a maximum of the size specified in -Xmx. So, for example, -Xmx4g will set the maximum heap size to 4 gigabyte. When both of these example parameter values are used together, i.e. –Xms512m –Xmx4g, the size of the heap will initially be 512 megabytes but will be allowed to grow to 4 gigabyte during the program’s lifecycle.

The amounts provided to each parameter will depend on the resources of the system running the application and the application’s memory requirements. It is therefore difficult to provide a generic suggestion for setting these parameters. Keep the following points in mind:

  • Setting the initial heap size too low could slow down the application’s operations, as the JVM will spend extra time increasing the heap size. But setting it too high may waste system resources if the application’s memory use is far below the allocation.
  • Setting the maximum heap size too low may cause the application to run out of memory during normal operations, and throw this exception: java.lang.OutOfMemoryError: Java heap space. However, setting it too high may cause the application to interfere with other applications on the system.

If -Xms and -Xmx are not explicitly set, the JVM will set the initial heap size based on the amount of available physical memory on the system and the maximum heap size based on the total amount of physical memory on the system. The exact details of these default settings will depend on the JVM implementation in use and whether it is in client or server mode.

startup.properties

If you are using startDesigner.bat \ .sh to launch Output Transformation Designer, open the startup.properties file for editing and locate the designer.version property; this property specifies the version to use when launching the application and you can enter an asterisk (*) as the value if you wish to always use the newest installed version.

If you are using startEngine.bat \ .sh to launch a standalone instance of the engine, open the startup.properties file for editing and locate the engine.version property; this property specifies the version to use when launching the engine and you can enter an asterisk (*) as the value if you wish to always use the newest installed version.

startup.properties includes a section to configure heap size used by Designer:

#####################################
###
### Controls how the product runs in Designer mode
###
### Use startup/startDesigner.bat or .sh to run
designer.jvmargs=-Xmx800M -Xms300M
designer.version=24.2.00_11801
designer.name=designer

startup.properties also includes a section to configure heap size used by Engine:

#####################################
###
### Controls how the product runs in Stand-alone engine mode
###
### Use startup/startEngine.bat or .sh to run
###
### Note: Web interfaces and many components will not be active in this mode.
###       Good for simple FileEvents runing transform processes
###
### To allow multiple instances to run, specify the unique name for
### variables engine_2.name, engine_3.name, etc.
###
### You can specify different jvmargs and version vars too.  If not specifed,
### the same settings for the first engine are used.
###
engine.jvmargs=-Xmx800M -Xms300M
engine.version=24.2.00_11801
engine.name=engine

So, to modify the maximum and minimum heap size you just need to modifify the property designer.jvmargs for Designer, or engine.jvmargs for Engine. i.e. to set a maximum of 4 Gb for Designer and 6 Gb for Engine:

designer.jvmargs=-Xmx4G -Xms300M
designer.version=24.2.00_11801
designer.name=designer

#…

engine.jvmargs=-Xmx6G -Xms300M
engine.version=24.2.00_11801
engine.name=engine

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