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Introduction


Installation

Discotek Heapster is a developer tool for helping determine if a JVM-based application has a memory leak and the cause of the leak. Memory leaks pose a serious threat to Java applications. Memory leaks occur when objects are no longer required, but are still referenced by rooted objects and consequently become rooted themselves. A rooted object cannot be garbage collected. Some examples of rooted objects are threads or system classloaders. These life time of these resources can span the life time of the JVM. If they reference unnecessary objects, the life time of these objects will also span that of the JVM. Once a leaky JVM nears its memory ceiling, garbage collection will be continually invoked. This will cause CPU to increase as it struggles to free up space for new object allocations. Unless detected by monitoring tools and handled accordingly, CPU may increase to 100% and may not recover, leaving the leaky application (and whatever other applications may be running in the same JVM) unresponsive.

This version of Heapster does not alert the developer when it think there is a memory leak, but future versions will include this functionality. This version is more useful for the proactive developer who wants to ensure an application does not have a memory leak or for a developer who knows there is a memory leak (perhaps due to an OutOfMemoryError) and would like to understand the root cause. Heapster provides the following functionality:


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Introduction


Installation