Resource accounting and reservation in Java Virtual Machine

The Java programming language was designed to developed small application for embedded devices, but it was a long time ago. Today, Java application are running in many platforms ranging from smartphones to enterprise servers. Modern pervasive middleware is typically implemented using Java because of its safety, flexibility, and mature development environment. However, the Java virtual machine specification has not had a major revised since 1999 [50]. It was designed to execute only a single application per instances, and thus it does not provide resource accounting or per-application resource reservations in the sense most middlewares consider application. Often, current pervasive middlewares are thus unable to reserve resources for critical applications, which may cause these applications to crash or hang up when there are not enough resources. Moreover, contemporary middlewares are unable to provide resource accounting. It makes impossible to apply adaptation policies to optimize resource use. Several researches had addressed these important issues. As result of these efforts some Java specification requests (JSR) have emerged. We consider there are seven JSRs relate to monitoring and to resource accounting and reservation: three for the Java Management eXtension API (JSRs 3, 160, 255), two for Metric Instrumentation (JSRs 138, 174) and two for resource-consumption management (JSRs 121, 284). The Java Management extension API only addresses monitoring and management: it does not define specific resource accounting or reservation strategies. JSRs 138 and 174 define monitors for the Java Virtual Machine. They are coarse grained, monitoring the number of running threads, the memory used, the number of garbage collections and so on. They monitor the entire virtual machine, not specific component so, they are useless to most middleware. Based on the Multitasking Virtual Machine [21], JSR 121 defines isolated JVM instances running in the same OS process, each instance with its own resources. Based on JRes [23], JSR 284 defines resource accounting for Java threads and processes. Together, JSRs 121 and 284 permit resource accounting and reservation for applications. However, the notion of application in JSR 121 is similar to a process at the OS level and it is incompatible with the notion of application of pervasive middlewares like OSGi [4], which relies on a notion of component.