{"id":1592,"date":"2015-08-19T11:39:23","date_gmt":"2015-08-19T11:39:23","guid":{"rendered":"http:\/\/mevss.jku.at\/?page_id=1592"},"modified":"2019-08-06T09:38:11","modified_gmt":"2019-08-06T09:38:11","slug":"anttracks","status":"publish","type":"page","link":"http:\/\/mevss.jku.at\/?page_id=1592","title":{"rendered":"AntTracks"},"content":{"rendered":"

AntTracks – Memory Monitoring using Accurate and Efficient Object Tracing for Java Applications<\/h1>\n
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Overview<\/h2>\n
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Object allocations and garbage collection can have a considerable impact on the performance of Java applications.
\nWithout monitoring tools, such performance problems are hard to track down, and if such tools are applied, they often cause a significant overhead and tend to distort the behavior of the monitored application.<\/p>\n

Overview<\/h2>\n

AntTracks VM: Tracing<\/h4>\n

Using the AntTracks VM, you can execute and trace any Java application.
\nThe VM will track every allocation, i.e., the allocation site (including the calling frames for frequent allocations), the allocated type, the allocating thread, the object size, as well as a number of other properties as well as object movements throughout the heap, and object deaths, i.e., when they are reclaimed by the garbage collector.<\/p>\n

In the paper Accurate and Efficient Object Tracing for Java Applications<\/a> we proposed a novel light-weight memory monitoring approach in which we trace allocations, deallocations and movements of objects using VM-specific knowledge. Information about these events is written into files for offline inspection in an analysis tool. The average run-time overhead is 4.68%, which seems to be fast enough for keeping tracing switched on even in production mode.<\/p>\n

\"Allocation<\/a>
Information recorded for every object allocation.<\/figcaption><\/figure>\n

To keep the size of the generated trace files as small as possible, we presented different concepts such as on-the-fly-compression during trace generation or trace file rotation. More details on this can be found in Efficient and Viable Handling of Large Object Traces<\/a>.<\/p>\n

\"Compression\"<\/a>
Compression to reduce trace file size<\/figcaption><\/figure>\n

Beside an object’s type and its allocation site, the objects it references and the objects it is reference by are the most valuable information to resolve memory problems. In Efficient Memory Traces with Full Pointer Information<\/a> we describe how information about the references between objects can be recorded and reconstructed with minimal overhead.<\/p>\n

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Pointer events in AntTracks.<\/figcaption><\/figure>\n

AntTracks Analyzer: Reconstruction and Memory Analysis<\/h4>\n

Our approach allows us to reconstruct the heap for any point in time and to do offline analyses on both the heap and on the trace. Efficient Rebuilding of Large Java Heaps from Event Traces <\/a>explains how the events in a trace file can be parsed and processed concurrently, as well as how heap states can be reconstructed from a trace file.<\/p>\n

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AntTracks’s data structure to store reconstructed heap objects.<\/figcaption><\/figure>\n

User-centered Offline Analysis of Memory Monitoring Data<\/a> and User-defined Classification and Multi-level Grouping of Objects in Memory Monitoring<\/a> present AntTracks’s heap state inspection. Once the heap for a certain point in time is reconstructed, users can select various classifiers, i,e., grouping criteria, based on which the heap’s objects get grouped by. Further, users can write new classifiers for detailed analysis based on their needs.<\/p>\n

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Filters and classifiers can be freely combined in AntTracks.<\/figcaption><\/figure>\n

Heap objects stay alive because they are (indirectly) reachable from so-called GC roots such as static fields or thread locals. Utilizing Object Reference Graphs and Garbage Collection Roots to Detect Memory Leaks in Offline Memory Monitoring<\/a> shows how information about GC roots can be collected into memory traces and how this information can be used in the Analyzer tool to find suspicious objects with a large ownership, i.e, those objects that keep alive a lot of other objects.<\/p>\n

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GC roots keep heap objects alive.<\/figcaption><\/figure>\n

Memory leaks are often caused by incorrectly handled data structures. For example, a developer may forget to remove objects from their containing data structures. These objects cannot be reclaimed by the garbage collector and will therefore accumulate over time. In Analyzing the Evolution of Data Structures in Trace-Based Memory Monitoring<\/a> and Analyzing Data Structure Growth Over Time to Facilitate Memory Leak Detection <\/a>we present novel techniques how to ease the inspection of memory leaks that are caused by data structures. Data structures are described using a DSL. The AntTracks analyzer is then able to detect instances of these data structures and automatically detects those data structures that exhibit the strongest growth, an indication for a possible memory leak.<\/p>\n

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Data Structure Analysis<\/figcaption><\/figure>\n

Visualizations are used in various domains to support the transfer of information. In AntTracks TrendViz: Configurable Heap Memory Visualization Over Time <\/a>we present how time-series charts in combination with a drill-down approach can be used to visualize an application’s memory evolution over time.<\/p>\n

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AntTracks TrendViz: Visualizing memory evolution over time using time-series charts and drill-down operations.<\/figcaption><\/figure>\n

About<\/h2>\n

This site provides downloads of our virtual machine and the analysis tool as well as tutorials on how to use both of them.<\/p>\n

The following introduction (“Cheat Sheet”) explains the basic features of AntTracks and their usage. Please use it to get started: AntTracks Introduction (“Cheat Sheet”)<\/a><\/p>\n

This project is a cooperation of the Institute for System Software, the Christian Doppler Laboratory for Monitoring and Evolution of Very-large-scale Software Systems and Dynatrace Austria.<\/p>\n

Sreenshots of the AntTracks Analyzer (2019):<\/h4>\n
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AntTracks Trace Overview<\/figcaption><\/figure>\n
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AntTracks Heap State Analysis<\/figcaption><\/figure>\n
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Garbage Collection Analysis in AntTracks<\/figcaption><\/figure>\n

Team<\/h4>\n