Some parameters are always implicitly defined by Splunk. Specifying any of the following parameters for your modular inputs has no effect. However, you could specify these to help clarify the usage: .. interval
Avoid using interval as a parameter. This parameter is reserved by Splunk for future use.
New with Splunk 6, you can optionally specify the interval parameter much as you can with scripted inputs.
Entering an empty value for interval results in a script only being executed on start and/or endpoint reload (on edit).
I tried to write a Java modular input for Splunk6 and use the interval=6000 in the inputs.conf.spec. According to the log, my input is only called once.