WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

720 WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

19.3.3 Viewing IBM Tivoli Composite Application Manager for WebSphere data

For information about how to view the data monitored by ITCAM for WebSphere Application

Server, refer to 16.6.3, “Viewing IBM Tivoli Composite Application Manager for WebSphere

data” on page 593. The process is the same for z/OS and distributed platforms.

19.4 Additional resources for monitoring

In this section, we discuss additional resources to be used while monitoring your WebSphere

environment.

19.4.1 IBM Support Assistant

IBM Support Assistant (ISA) is a software workbench provided by IBM to help you diagnose

and solve questions about IBM software. It offers several tools as add-ons to help you analyze

logs, heap dumps, Java dumps, and so on. For details about the tools and features available

for z/OS and how to install and configure them, see Introducing the IBM Support Assistant for

WebSphere Application Server on z/OS at the following website:

http://www-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/WP101575

19.4.2 Verbose garbage collection

Verbose garbage collection was mentioned in 16.4.1, “JVM memory and CPU usage” on

page 576. Again, assuming there is appropriate disk space, a monitoring strategy must

include verbose garbage collection. To enable verbose garbage collection:

1. Click Servers  Server Types  WebSphere application servers  <your server> 

Server Infrastructure  Java and process management  Process definition, as

shown in Figure 19-6.

Figure 19-6 Process definition type

2. You can define the garbage collection for any of the above processes. However, it is more

efficient to set it to run in a servant process, where the application runs and most of the

tuning occurs automatically. Click Servant  Additional Properties  Java Virtual

Machine, and select the Verbose garbage collection box, as shown on Figure 19-7 on

page 721.

Chapter 19. Monitoring z/OS systems 721

Figure 19-7 Enable verbose garbage collection

Verbose garbage collection can also be enabled using the Runtime tab, as shown in

Figure 19-8.

Figure 19-8 Enabling verbose garbage collection at run time

When verbose garbage collector is enabled, a report is written to the output stream each time

the garbage collector runs. The report is typically located in SYSOUT DD from servant output.

In Version 7, WebSphere used an optimal throughput (optthruput) algorithm for garbage

collection. Currently, generational concurrent garbage (gencon) collection is used, allowing for

performance improvements. Because optthruput uses a large contiguous heap shared by all

threads, when garbage collection is invoked, all of this area is scanned. This policy is

Note: After enabling verbose garbage collection, restart the server to validate the change.

722 WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

beneficial for applications that demand optimal throughput, but it has long pause times.

Generational concurrent garbage collection divides the heap memory in two pieces:

 Nursery, for new objects

 Tenured, for aged objects

So, in this policy, the time spent to scan one of the areas is shorter.

Example 19-3 shows a sample garbage collection entry in SYSOUT.

Example 19-3 Garbage collection entry

<exclusive-start id="274" timestamp="2011-07-20T22:44:56.947"

intervalms="34510.096">

<response-info timems="0.046" idlems="0.046" threads="0"

lastid="0000004808DCB900" lastname="WebSphere non-WLM Dispatch Thread t=007c7c68"

/>

</exclusive-start>

<af-start id="275" totalBytesRequested="40" timestamp="2011-07-20T22:44:56.948"

intervalms="34510.089" />

<cycle-start id="276" type="scavenge" contextid="0"

timestamp="2011-07-20T22:44:56.948" intervalms="34510.087" />

<gc-start id="277" type="scavenge" contextid="276"

timestamp="2011-07-20T22:44:56.948">

<mem-info id="278" free="157892256" total="261947392" percent="60">

<mem type="nursery" free="0" total="60620800" percent="0" />

<mem type="tenure" free="157892256" total="201326592" percent="78">

<mem type="soa" free="147826336" total="191260672" percent="77" />

<mem type="loa" free="10065920" total="10065920" percent="100" />

</mem>

<remembered-set count="17359" />

</mem-info>

</gc-start>

<allocation-stats totalBytes="42822544" >

<allocated-bytes non-tlh="94144" tlh="42728400" />

<largest-consumer threadName="WebSphere non-WLM Dispatch Thread t=007c7c68"

threadId="0000004808DCB900" bytes="40718768" />

</allocation-stats>

<gc-op id="279" type="scavenge" timems="105.492" contextid="276"

timestamp="2011-07-20T22:44:57.053">

<scavenger-info tenureage="6" tiltratio="70" />

<memory-copied type="nursery" objects="226786" bytes="14839960"

bytesdiscarded="4904" />

<memory-copied type="tenure" objects="65747" bytes="4425048"

bytesdiscarded="1512" />

<finalization candidates="976" enqueued="572" />

<references type="soft" candidates="4850" cleared="0" enqueued="0"

dynamicThreshold="29" maxThreshold="32" />

<references type="weak" candidates="567" cleared="45" enqueued="16" />

<references type="phantom" candidates="2" cleared="0" enqueued="0" />

</gc-op>

<gc-end id="280" type="scavenge" contextid="276" durationms="105.833"

timestamp="2011-07-20T22:44:57.053">

<mem-info id="281" free="200176936" total="263258112" percent="76">

<mem type="nursery" free="46784264" total="61931520" percent="75" />

<mem type="tenure" free="153392672" total="201326592" percent="76">

<mem type="soa" free="143326752" total="191260672" percent="74" />