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Default parameters for JvmGCDetailsTest

Manual memory management is time consuming, and error prone. Most programs still contain leaks. This is all doubly true with programs using exception-handling and/or threads. Garbage collection (GC) is a part of a Java application's JVM that automatically determines what memory a program is no longer using, and recycles it for other use. It is also known as “automatic storage (or memory) reclamation”.  The JVM Garbage Collections test reports the performance statistics pertaining to the JVM's garbage collection.

This page depicts the default parameters that need to be configured for the JvmGCDetailsTest.

  • The TEST PERIOD list box helps the user to decide how often this test needs to be executed. 

  • This test can extract metrics from the Java application using either of the following mechanisms:

    • Using SNMP-based access to the Java runtime MIB statistics;

    • By contacting the Java runtime (JRE) of the application via JMX

    To configure the test to use SNMP, select the SNMP option. On the other hand, choose the JMX option to configure the test to use JMX instead. By default, the JMX option is chosen in the MODE text box.

  • For the eG agent to collect metrics from the target IBM WebSphere Liberty server, the local connector should be enabled on the target server. Once the connector is enabled, a com.ibm.ws.jmx.local.address file will be created in the ${server.output.dir}/logs/state folder. The eG agent uses this file to connect to the target server and collect the required metrics from it. Therefore, specify the exact path to this file in the SERVICE URL PATH text box. For example, in case of Windows environments, the Service URL Path can be C:\wlp\usr\servers\server1\logs\state and in case of Linux environments, the SERVICE URL PATH can be /opt/wlp/ur/servers/server1/logs/state.

  • The SNMPPORT parameter appears only if the MODE is set to SNMP. Here specify the port number through which the server exposes its SNMP MIB. Ensure that you specify the same port you configured in the management.properties file in the <JAVA_HOME>\jre\lib\management folder used by the target application.

  • The SNMPVERSION parameter appears only if the MODE is set to SNMP. The default selection in the SNMPVERSION list is v1. However, for this test to work, you have to select SNMP v2 or v3 from this list, depending upon which version of SNMP is in use in the target environment.

  • The SNMPCOMMUNITY parameter appears only if the MODE is set to SNMP. Here, specify the SNMP community name that the test uses to communicate with the mail server. The default is public. This parameter is specific to SNMP v1 and v2 only. Therefore, if the SNMP version chosen is v3, then this parameter will not appear.

  • The USERNAME parameter appears only when v3 is selected as the SNMPVERSION. SNMP version 3 (SNMPv3) is an extensible SNMP Framework which supplements the SNMPv2 Framework, by additionally supporting message security, access control, and remote SNMP configuration capabilities. To extract performance statistics from the MIB using the highly secure SNMP v3 protocol, the eG agent has to be configured with the required access privileges - in other words, the eG agent should connect to the MIB using the credentials of a user with access permissions to be MIB. Therefore, specify the name of such a user against this parameter. 

  • The CONTEXT parameter appears only when v3 is selected as the SNMPVERSION. An SNMP context is a collection of management information accessible by an SNMP entity. An item of management information may exist in more than one context and an SNMP entity potentially has access to many contexts. A context is identified by the SNMPEngineID value of the entity hosting the management information (also called a contextEngineID) and a context name that identifies the specific context (also called a contextName). If the USERNAME provided is associated with a context name, then the eG agent will be able to poll the MIB and collect metrics only if it is configured with the context name as well. In such cases therefore, specify the context name of the USERNAME in the CONTEXT text box. By default, this parameter is set to none.

  • Specify the password that corresponds to the above-mentioned USERNAME in the AUTHPASS text box. This parameter once again appears only if the SNMPVERSION selected is v3.

  • Confirm the AUTHPASS by retyping it in the CONFIRM PASSWORD text box.

  • The AUTHTYPE parameter too appears only if v3 is selected as the SNMPVERSION. From the AUTHTYPE list box, choose the authentication algorithm using which SNMP v3 converts the specified USERNAME and PASSWORD into a 32-bit format to ensure security of SNMP transactions. You can choose between the following options:

    • MD5 - Message Digest Algorithm

    • SHA - Secure Hash Algorithm

  • The ENCRYPTFLAG appears only when v3 is selected as the SNMPVERSION. By default, the eG agent does not encrypt SNMP requests. Accordingly, the ENCRYPTFLAG is set to No by default. To ensure that SNMP requests sent by the eG agent are encrypted, select the Yes option.

  • If the ENCRYPTFLAG is set to Yes, then you will have to mention the encryption type by selecting an option from the ENCRYPTTYPE list. SNMP v3 supports the following encryption types:

    • DES - Data Encryption Standard

    • AES - Advanced Encryption Standard

  • Specify the encryption password in the ENCRYPTPASSWORD text box.

  • Confirm the encryption password by retyping it in the CONFIRM PASSWORD text box.

  • Specify the duration (in seconds) for which this test should wait for a response from the target Java application. If there is no response from the target beyond the configured duration, the test will timeout. By default, the TIMEOUT parameter is set to 240 seconds.

  • By default, in an IT environment, all data transmission occurs over UDP. Some environments however, may be specifically configured to offload a fraction of the data traffic - for instance, certain types of data traffic or traffic pertaining to specific components - to other protocols like TCP, so as to prevent UDP overloads. In such environments, you can instruct the eG agent to conduct the SNMP data traffic related to the monitored target over TCP (and not UDP). For this, set the DATA OVER TCP flag to Yes. By default, this flag is set to No.

  • Once the necessary values have been provided, clicking on the UPDATE button will register the changes made.

When changing default configurations of tests, the values with "$" indicate variables that will be replaced by the eG system according to the specific server being managed - for instance, $hostName is the host/nickname of the target host, $port is the port number of the server being monitored. E.g., for a server xyz:80, $hostName will be changed automatically by the eG manager to "xyz" and $port will be changed to "80" when configuring a test.