Can be used to set maximum java heap size that can be used by the program. A low value can cause frequent OutOfMemory errors which might make the FioranoMQ server unreliable or low performance if the program's heap memory is reaching the maximum heap size as the GC will be run more frequently.
You may see the amount of memory you use exceeds the amount specified for the Xmx parameter. While Xmx limits the java heap size, java will allocate memory for other things, including a stack for each thread. It is not unusual for the total memory consumption of the VM to exceed the value of –Xmx.
Default value for fmq server is 256 MB
Example: -Xmx256m sets maximum heap size to 256 MB
Can be used to set initial java heap size to be used by the program. This is useful if the program consumes a large amount of heap memory right from the start. This avoids the JVM to be constantly increasing the heap resulting in better performance.
Default value for fmq server is 128 MB
Example: -Xms128m sets minimum heap size to 128 MB
The value must be a multiple of, and greater than, 1024 bytes (1KB).