Snapshot file format

General

Snapshots are stored in XML-Format. The overall structure is:

Profile

This section contains java-method profiling data collected by byte-code-instrumentation. Below you see an extract of a snapshot-file (Complete snapshot »):

Profiling data is grouped by threads. Each thread reports the following data:

Attribute	Description
name	The name of the thread.
cpuTime	The consumed CPU time (nanoseconds).
isAlive	True if the thread is alive.

The XML-structure below <thread> shows the method call stack. Method profiling data comprises:

Attribute	Description
name	The method's full qualified name (contains package name) and human readable signature.
signature	The method's signature as defined by the Java specification
count	Invocation count
methodElapsed	Elapsed time in microseconds excluding called (and profiled) methods.
method	CPU time consumption in microseconds excluding called (and profiled) methods.
cumulatedElapsed	Cumulated elapsed time of method and all methods is has called.
cumulated	Cumulated CPU time of method and all methods is has called.
overheadCumulated	CPU time the agent consumed to collect profile data for this and all called methods. The ratio overheadCumulated / cumulated is a measure for the quality of the profiling results.
overheadMethod	CPU time the agent consumed to collect profile data for this method.
exceptions	Number of exceptions thrown.

Sampler

This section contains java-method profiling data collected by sampling. Below you see an extract of a snapshot-file (Complete snapshot »):

Profiling data is grouped by threads. Each thread reports the following data:

Attribute	Description
name	The name of the thread.
cumulated	The number of recorded hits with thread being in state Thread.State.RUNNABLE.
cumulatedElapsed	The number of recorded hits regardless of the thread's state.
cpuTime	The consumed CPU time (nanoseconds).
elapsedTime	The total elapsed time (nanoseconds) i.e. the time the thread is running.
isAlive	True if the thread is alive.

The XML-structure below <thread> shows the method call stack. Method profiling data comprises:

Attribute	Description
name	The method's full qualified name (contains package name). Contrary to byte-code-instrumentation (see <profiler>, doesn't provide signature.
hits	The number of recorded hits with thread being in state Thread.State.RUNNABLE.
elapsed	The number of recorded hits regardless of the thread's state.
cumulated	Cumulated number of recorded hits (i.e. this method and all called methods) with thread being in state Thread.State.RUNNABLE.
cumulatedElapsed	Cumulated number of recorded hits regardless of the thread's state.

Memory

This section contains object allocation data collected by byte-code-instrumentation. Below you see an extract of a snapshot-file (Complete snapshot »):

<memory>
<thread name="AWT-EventQueue-0">
    <memory class="java.awt.geom.AffineTransform" count="69" max="799"/>
    <memory class="java.awt.Rectangle" count="61" max="1446"/>
    <memory class="sun.java2d.pipe.Region" count="37" max="373"/>
    <memory class="java.lang.Object" count="7" max="7"/>
    ....

</thread>
    <thread name="AWT-Windows">
    <memory class="java.awt.Rectangle" count="45" max="88"/>
    <memory class="java.awt.event.PaintEvent" count="45" max="88"/>
    <memory class="sun.awt.EventQueueItem" count="43" max="88"/>
</thread>
</memory>

The object allocations are grouped by threads which allocated the respective objects. For each allocated object, the following data is provided:

Attribute	Description
class	The class name of the allocated object
count	The number of objects currently allocated
max	The maximum number of previously allocated objects.

Coverage

This section contains coverage metrics collected by byte-code-instrumentation. Below you see an extract of a snapshot-file (Complete snapshot »):

<coverage>
    <class name="com.terrasoft.profilerj.tutorial.Example01" source="Example01.java">
        <method name="<init>" signature="(Ljava/lang/String;)V" firstline="11" count="0">
            <footprints>0 0 </footprints>
        </method>

....
</coverage>

The tag <class> contains general information about the class whose methods have been checked vor coverage:

Attribute	Description
class	The name of the class
source	The source file (only available if class was compiled with debug switch "on")

Beneath the class node you find a <method> tag for each method of the class.

Attribute	Description
name	The name of the method
signature	The method's signature
firstline	The line in the source code where the method begins (i.e. the first executable statement)
count	The number of times this method has been invoked.

The tag <footprints> contains integers delimited by blanks. Each source line of the respective method corresponds to exactly one number, i.e. the first line of the method corresponds to the first integer. Each number may be -1, 0 or greater than 0:

-1 : The line doesn't contain executable code (e.g. empty lines, comments ...)
0 : The respective line contains executable code which has never been reached.
greater 0: The value shows how often the line has been executed.