TechTip: Free App Locates Memory Leaks

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Did you really think that you didn't have to worry about this if you're a Java developer?

 

 Java   provides developers with false assurance that memory leakage is something   they need not be concerned with. Even with Java Garbage Collection, leaks may occur. And further complicating the issue, OS memory usage may be stable while the JVMs fluctuate.

 

The   challenge is in detecting that there are leaks and then determining where they are located. There are so many places where memory could be leaking that it is non-trivial to manually check them all.

 

With AutoPilot Heap  Detective, you can rapidly diagnose your memory leaks. This free application provides diagnostics to find the top offenders and simplify the task of determining the cause of these Java memory leaks. Heap Detective gathers all memory usage information for you in a straightforward interface in order to pinpoint your leaks. Heap Detective finds all objects in heap, capturing instance count, total size, and average size. It reports on top objects by retained size to find the likely culprits.

 

The   typical types of leaks that Heap Detective can be applied to include these:

 

  • Out of Memory
  • Increased GC activity
  • Heap Usage
  • Thread Leaks, Handle Leaks: Applications are spawning threads, and these threads are not properly shutting down, resulting in leaks.
  • JDBC Prepared Statements: Even though the objects are being garbage-collected, it doesn't necessarily mean that the resources allocated by the underlying databases are being deallocated. Typically, you will find that the application developers are not properly closing the prepared statements.
  • Class  Loader Leaks: Class loader leaks are very difficult to spot, but they do happen, especially when redeploying applications or when working with applications with custom class loaders.

 

Regardless of the reasons for these leaks, dealing with composite applications and multiple moving parts can be a real challenge in application development and production support. Due to the complexity, it is often impossible to spot the resource or component systems that are exhibiting leak behavior.

 

Here's a list of features:

  • Gathers detailed memory usage
  • Analyzes JVM heap remotely on any running JVM without generating a heap dump
  • Forces Garbage Collection remotely
  • Shows JVM summary: Java properties, heap usage, and free memory
  • Drills down to areas where memory is used by Instance Count, Retained Size, and Shallow Size
  • Drills down to what objects hold references to top memory consumers
  • Takes and compares multiple heap snapshots

 

 

AutoPilot Heap Detective doesn't use the Java resources it is diagnosing. It's written in C/C++ and thus doesn't use Java Heap.

 

This production-ready app doesn't run continuously; it takes snapshots. And it doesn't impact Java application performance.

 

With remote inspection of Java memory, there's no need for colocation of the tool with the JVM.

 

113012NastelFig1aphd-top10 

Figure 1: This report shows a historical view of heap with the total size of each object. The report is sorted by the largest absolute change.

 

113012NastelFig2aphd-history   

Figure 2: This view shows the "top objects by retained size" within heap. A user can interact with this view and highlight a heap object, see its properties such as retained size, the fields it is comprised of, and all the references it has to objects within the JVM.

 

There's an optional upgrade path for Heap Detective to enable leak detection as well as leak diagnostics. Integrating Heap Detective with Nastel AutoPilot provides analysis, diagnostics, and alerting as part of an application performance monitoring solution.

But Wait! There's More!

Nastel also offers another free product, MQSonar, that performs as a "ping" for WebSphere MQ. Download AutoPilot for MQSonar for free.

 

Nastel  Technologies provides middleware-centric application performance monitoring solutions for mission-critical applications from the datacenter to the cloud and is the only monitoring vendor with a unified platform to support all software and  appliance-based middleware technology requirements,

 

Nastel is a privately held company headquartered in New York, with offices in the  U.S., the U.K., Germany, and Mexico, and a network of partners throughout  Europe, the Middle East, Latin America, and Asia. For more information, visit   www.nastel.com.

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