A |
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| active mode | | An HPjmeter JVM agent that is part of an open
console session and is collecting data from the JVM and application
and is sending it to a console.
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| agent | | A module that represents HPjmeter in your environment. HPjmeter provides
two types of agents, a node agent and a JVM agent.
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B |
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| Batch mode | | An HPjmeter JVM agent that is installed, configured,
and is collecting data, but is not connected to a console and is not
part of a session. The collected data is stored in a file on the managed
node that you can open later from the console.
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| BCI | | See bytecode instrumentation.
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| bytecode instrumentation | | Instrumentation of Java bytecode inserts a special,
short sequence of bytecode at designated points in the Java classes
of an application to facilitate runtime analysis of those classes
during monitoring.
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C |
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| cached session | | A session created when a running JVM terminates
on its own, or when you close an active session. The data in a cached
session is available for analysis, but it is no longer connected to
a running JVM and is no longer collecting additional data.
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| call graph | | Displays the capture of “call” relationships
between the methods. The nodes of the call graph represent the program
methods, while the directed arcs represent calls made from one method
to another. In a call graph, the call counts or the timing data are
collected for the arcs.
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| call graph trees | | Call graph data presented in a collapsible and
expandable tree hierarchy. See also call graph.
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| clock time | | The time as measured by an external independent
clock.
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| confidence | | The measure of reliance or assurance that HPjmeter diagnosed
the situation correctly.
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| confidence interval | | The HPjmeter graphical representation of probability
that the displayed values are correct. As the number of samples taken
increases, the probability increases.
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| console | | The main window containing the menu and button
controls for monitoring live applications and analyzing captured data.
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| Console filters | | The Session Preferences window
allows you to specify the classes to measure when you open a session
with a JVM agent. For details, see Controlling Data Collection and Display
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| CPU time | | Time spent by any central processing unit (CPU)
to execute a thread.
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| CPU virtual times | | Times when a thread is runnable, but not necessarily
running. Depending on the actual hardware, operating system, and Java
VM, this time may also include I/O time, but generally CPU virtual
times are a good approximation of real CPU time consumed by the application.
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| creation rate | | The calculated rate at which new objects are occupying
the heap.
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D |
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| dormant mode | | An HPjmeter JVM agent that is installed and configured,
but is not part of an open console session and is, therefore, not
collecting data from the JVM and applications and is not sending data
to a console.
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| dynamic attach | | In HPjmeter, the ability to find and connect to
a running JVM on a machine that has the HPjmeter node agent running,
but the JVM was started without using HPjmeter options.
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E |
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| eden | | That part of the heap where new and/or short-lived
objects (the young generation) are created and used.
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| ephemeral port
number | | a temporary port number assigned from a range
of numbers designated for this purpose.
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| exclusive times | | The accumulated total times used by a method,
but not including the time used by the methods that were called from
it.
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F |
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| filter | | To exclude the measurement of specified classes. HPjmeter provides
two methods to control how information is collected and displayed,
JVM agent filters and console filters. For details, see Controlling Data Collection and Display
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G |
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| garbage collection | | The process of automatically freeing memory by
removing objects that are no longer referenced by the program.
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H |
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| hot spot | | A section of code, typically a method, with a
higher-than-normal level of execution or access requiring high CPU
usage.
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I |
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| inclusive time | | The accumulated total time used by all invocations
of the method and all methods that were called from it directly or
indirectly.
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| inlining | | Replacing a call to a function with an instance
of the function; usually done at compile time.
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J |
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| Java Management
Extensions | | See JMX .
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| JMX™ | | Java Management Extensions.
API for managing and monitoring applications, devices, services, and
JVMs. For API specifics, see the Java Community Process web (http://jcp.org/en/home/index):
Java Management Extensions (JMX) Specification (JSR3) and JMX Remote
Specification (JSR160).
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| JVM | | Java Virtual Machine
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| JVM agent | | A module running on each managed node that collects
data and sends it to the node agent, which sends it to the console.
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| JVM agent filters | | The include and exclude options to the JVM agent allow you to filter metrics by class name.
For details, see Controlling Data Collection and Display
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| JVMPI | | JVM Profiler Interface
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| JVMTI | | JVM Tool Interface
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L |
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| lingering objects | | accumulated live objects that clog the heap, creating
memory leaks.
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| lock contention | | The summary time measured from the moment the
thread requests a Java lock until the lock is actually granted.
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| Lock Delay | | The time elapsed between the moment a thread tries
to acquire a lock and the time the thread enters the monitor.
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M |
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| managed node | | A computer on which the HPjmeter node agent and
JVM agent are installed.
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| memory leak | | HPjmeter uses the long term linear upward trends
in the heap size after garbage collections to calculate the likely
presence of memory leaks. See How Memory Leak Detection Works
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| metadata | | Objects needed by the Java interpreter and for reflection in garbage collection.
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| method | | A function defined in a class. Unless specified
otherwise, a method is not static.
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| method call count | | The number of times each function (method) of
the program was called during a run.
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| method clock time | | The actual time spent in each of the methods of
the program.
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| metric | | In this context, a mapping that associates numerical
values with static or dynamic elements such as program functions,
variables, classes, objects, types, or threads.
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N |
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| node agent | | A process that manages communication between JVM
agents and a console. Node Agent
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O |
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| old generation | | Objects in the heap that have survived a successive
number of garbage collections, and have been moved to the old space
in the heap.
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P |
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| package | | A group of types. Packages are declared with the
package keyword.
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R |
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| reduction | | Accumulating data during tracing such that consecutive
calls from the same caller to the same callee increase the recorded
time value for a call.
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S |
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| scavenge | | Incremental, lightweight garbage collection of
primarily short-lived objects in order to free space.
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| scope | | The breadth of view across thread-based profile
data. HPjmeter lets you look at a single thread, a group of threads,
or the entire application.
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| service-level objective | | service-level objective. A service-level objective
(SLO) partitions a service-level agreement (SLA) into metrics and
operational information to enforce and/or monitor the SLA.
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| session | | An open, live connection between an console and
a JVM agent running on a managed node. An open session has associated
with it a set of metrics, filters, and alerts that are configured
when you open the session.
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| severity | | The measure of the expected impact of the detected
situation on the application stability.
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| SLO | | See service-level objective.
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| SSL | | Secure Sockets Layer
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| stop-the-world
time | | Duration of a full garbage collection where processing
stops during the collection time.
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T |
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| thrashing | | Excessive paging due to a disparity between physical
memory actually available to the application and the specified maximum
size for memory usage.
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| thread spectrum | | When profiling, the distribution of thread lifetime
over the possible thread states.
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| time slice | | Time slice entries represent the life span of
the current monitoring session for an application. You can view data
throughout the life span of a time slice.
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| train | | Optional structure within the heap that is intermediate
between the eden space and the old space. The train is a related collection
of smaller memory spaces (cars) that have garbage
collected incrementally according to the train algorithm.
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| train algorithm | | Mathematical formula that describes incremental
garbage collection of related old objects. The purpose of train garbage
collection is to reduce the length of pause due to GC that is visible
to users of the software.
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V |
|---|
| visualizer | | The pop-up screens where you see graphical or
tabular displays of data. Visualizers provide contextual controls
based on the data displayed. See Using Visualizer Tool Bars
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|---|
Y |
|---|
| young generation | | New and/or short-lived objects in the heap. Usually
garbage collections are done frequently in the young generation by
scavenging the eden space.
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