Some basic concepts and terminology
- Sampling
- The process by which Application Performance Analyzer measures
activity – recording data observed during repeated, timed “snapshots”–
is called “sampling.” Application Performance Analyzer saves
the observed data in a “measurement file,” sometimes referred to as
a “sample file.”
- Non-intrusive technology
- Application Performance Analyzer’s
sampling mechanism is efficient, effective, and, above all, non-intrusive. Application Performance Analyzer’s
measurement engine will never schedule any task to execute in the
address space being measured.
- The Application Performance Analyzer started
task
- This started task performs all of Application Performance Analyzer’s
measurements. Normally, a single Application Performance Analyzer started
task is active in a single MVS™ instance. In a multiple-MVS instance
installation (including a sysplex), an Application Performance Analyzer started
task needs to be active in each MVS instance
in which measurements are to be performed.
- The Application Performance Analyzer Listener
started task
- This started task manages the communication between the Application Performance Analyzer GUI
and the Application Performance Analyzer started
tasks. Multiple workstation GUI users communicate through one Listener
to any compatible Application Performance Analyzer started
task defined on a single MVS instance.
- Multiple started tasks
- In special situations you might want to run multiple Application Performance Analyzer started
tasks in a single operating system instance. For example, you might
want to do this when making a transition from one product version
to the next. Each Application Performance Analyzer instance
is identified by a unique four-character instance identifier. For
simplicity, this manual discusses Application Performance Analyzer in
the context of a single-instance configuration.
- The Application Performance Analyzer product
code and Application Performance Analyzer instance
ID
- The module name prefix (product code) used by Application Performance Analyzer is
CAZ. We have chosen CAZ0 as the default Application Performance Analyzer instance
identifier, and it is used for examples in this document.
- The ISPF component
- Application Performance Analyzer’s
ISPF component provides the user with full, interactive access to
the product’s functionality. A single, gateway dialog serves as the
entry point to all interactive services. The interactive services
fall into two basic categories: scheduling and managing measurement
requests; and analyzing measurement data.
- The Graphical User Interface
- The Application Performance Analyzer graphical
user interface (GUI) is a CICS Explorer plug-in that provides an alternative
to the Application Performance Analyzer ISPF
interface. It communicates with the Application Performance Analyzer started
task through the Application Performance Analyzer Listener
started task.
- Common data store
- An
optional data set unique to each Application Performance Analyzer started
task (except in a sysplex environment), used to store lists of data
set and directory names containing source program mapping files, and
source program mapping associations. It includes one common list of
data set names that can be shared amongst all users, and personal
source mapping file lists for individual users. Individual users maintain
their personal source mapping file lists using the ISPF A03 and A04
panels or the GUI Mapping Repository feature. Administrators maintain
the common source mapping file list using the ISPF A05 panel or the
GUI Mapping Repository feature.
- IEFUSI exit routine
- One Application Performance Analyzer module
will receive control during the initiation of all job steps and started
tasks, via the Step Initiation Exit (IEFUSI). During execution of
this exit routine, Application Performance Analyzer determines
whether a measurement has been scheduled for the job step, or started
task. If it has, the exit routine will initiate sampling for the target
address space. Application Performance Analyzer requires
that the exit module (CAZ00990) in library hlq.SCAZLINK be
added to the LNKLST.
- Post-process initiation exit
- One Application Performance Analyzer module
will receive control during the initiation of all USS processes via
the Post-process initiation exit (BPX_POSPROC_INIT). During execution
of this exit routine, Application Performance Analyzer determines
whether the process is a child process of one that is currently being
measured by Application Performance Analyzer.
If it is, the exit routine will initiate sampling for this target
process. Application Performance Analyzer requires
that the exit module (CAZ00991) in library hlq.SCAZLINK be added to
the LNKLST.
- IEFU83 exit routine
- This is an optional SMF Record exit that Application Performance Analyzer will
enable when measuring WebSphere applications. The exit will receive
control whenever the SMFWTM or SMFEWTM macro is invoked by WAS. It
captures SMF type 120 subtype 9 records for active sampling requests
that have the WAS data extractor turned on. All other SMF records
are ignored. Application Performance Analyzer requires
that the exit module (CAZ00993) in library hlq.SCAZLINK be
added to the LNKLST. When this exit is enabled, you must determine
the amount of above-the-bar common storage that a WAS sampling session
is permitted to allocate. This value is specified in the MemObjSize
in the Application Performance Analyzer-started
task configuration.
- IEFU84 exit routine
- This is an optional SMF Record exit that Application Performance Analyzer will
enable when the DB2 SMF configuration option has been enabled. The
exit will receive control whenever the SMFWTM or SMFEWTM macro is
invoked by DB2. It captures SMF type 101 records for active sampling
requests that have the DB2+ data extractor turned on. All other SMF
records are ignored. Application Performance Analyzer requires
that the exit module (CAZ00993) in library hlq.SCAZLINK be
added to the LNKLST. When this exit is enabled, you must determine
the amount of above-the-bar common storage that a DB2+ sampling session
are permitted to allocate. This value is specified in the MemObjSize
in the Application Performance Analyzer-started
task configuration.
- J9VM sampling module
- One Application Performance Analyzer module
is dynamically loaded and invoked by the JVMTI agent module CAZJVMTI
(for 31-bit) or CAZJ64TI (for 64-bit) when sampling Java V5 &
V6 jobs. The module processes requests by CAZJVMTI (for 31-bit) or
CAZJ64TI (for 64-bit) to record Java sample data in the sampling data
space. Application Performance Analyzer requires
that modules CAZ00102 (called by CAZJVMTI)
and CAZ00104 (called by CAZJ64TI) in library hlq.SCAZLINK be
added to the LNKLST.