TS/MP 2.5 System Management Manual

between these objects and server processes can slow down the response time of PATHMON
processes compared to other commands (from PATHCOM or SPI).
• Creating and deleting links
If the PATHMON process is configured so that it is constantly creating and deleting links, the
server might wait for processor cycles, causing incoming transactions to be placed on the
server-class wait queue.
For more information about PATHMON performance and steps you can take to improve it, see
“Managing PATHMON Process Performance” (page 101).
Understanding the Causes of Link Dissolution
A PATHMON process, ACS subsystem processes, or TCP process, or a server process (indirectly)
can delete a link. This table describe how a link manager can cause deletion of a link.
A link manager will return a link to a server process when any of these situations occur:
ActionCause
Returns the dynamic link.A “DELETEDELAY” timer expires for a dynamic link.
Returns the link.An OPEN error occurs on a link.
Returns all links for this server process, allowing current I/O
to complete.
An I/O error occurs on a link. (I/O errors include timeouts
caused by the SET SERVER TIMEOUT value. Timeouts
caused by the SERVERCLASS_SEND_ timeout value are not
considered to be link errors.)
Returns all links for this server process, allowing current I/O
to complete.
The PATHMON process sends a server class stop request.
Returns all links to the server process, allowing current I/O
to complete.
The PATHMON process sends a forced delink request.
Deletes all links owned by that PATHMON process,
allowing current I/O to complete. Consequently, no links
are returned to the PATHMON process.
The PATHMON process sends an external shutdown
notification.
Deletes all links owned by that PATHMON process,
allowing current I/O to complete. Consequently, no links
are returned to the PATHMON process.
The PATHMON process returns an unexpected I/O error
or close message, or the link manager detects a message
protocol error.
Deletes all links owned by that PATHMON process,
allowing current I/O to complete. Consequently, no links
are returned to the PATHMON process.
A link manager gets an error trying to communicate with
the PATHMON process.
The PATHMON process and Server Links
If a server process goes down, the operating system automatically informs the PATHMON process
that owns that server class. The PATHMON process then dissolves all links to that server process
by sending a message to all ACS subsystem processes with established links to that server process.
Because servers are (usually) coded to stop themselves when all openers have closed them, system
managers seldom need to worry about stopping servers.
Managing PATHMON Process Performance
The performance of the PATHMON process is critical to response time for applications and
management tasks.
Generally, in the production environment, the PATHMON process must be busy only during startup
and shutdown of the PATHMON environment. If the PATHMON process is very busy at times other
than startup and shutdown, you must take steps to alleviate the workload.
These sections describe factors that can cause poor performance and steps you can take to improve
performance.
Managing PATHMON Process Performance 101