Describes Java-related tools and analysis methods available on IBM i

Includes tools such as the wrkjvmjob provided in I 6.1 and above, as well as an introduction to the related macros provided in STRSST. This article chooses some author in the work and the practice process frequently uses the function and the choice to explain, and interspersed some http://www.aliyun.com/zixun/aggregation/17253.html "" "The common question summary and the ponder.

IBM Marvell for Java (IT4J) is an IBM Java Virtual machine that is also a trend for Java virtual machines in the IBM I operating system. We usually call this Java virtual machine J9.

Unlike other operating systems, J9 has a number of unified management and analysis tools on IBM I, such as Wrkjvmjob, Prtjvmjob, and Genjvmdmp. In addition to these easy-to-use tools, there are a number of features available in the STRSST application as well as related macros. All of these tools and macros help users better manage all the J9-related jobs in the system, as well as analyze and collect data for problematic assignments. Below I will explain to some common tools.

IBM I J9 Introduction

V1 is the product name of the Java virtual machine on IBM I, such as 5722JV1 on I 5.4 and 5761jv1 on i6.1 and i7.1. It is worth mentioning that JV1 this product is distributed to end users as part of the IBM I operating system, so it will be possible to install different versions of J9 on the IBM I system without extra cost, and IBM technical support is available. Different versions of J9 occupy different options for the JV1 product, such as the following table:

Table 1 The relationship between the JV1 product options and the J9 JDK version is as follows:

J9 version JV1 options IBM i 5.4 IBM i 6.1 IBM i 7.1 JDK 1.4.2 64-bit 13 unsupported support JDK 5.0 32-bit 8 support support JDK 5.0 64-bit 9 unsupported support JDK 6.0 32-bit 11 support support JDK 6.0 64 bit 12 unsupported support JDK 7.0 32-bit 14 unsupported support JDK 7.0 64-bit 15 unsupported support not supported

This article will use the options, JDK 6.0 32bit as an example to explain and analyze the tools.

Wrkjvmjob Tools

First, let's look at Wrkjvmjob. This tool is a very common and effective tool for managing all J9 jobs on IBM i. It can be used to complete the display and management of J9 operations, mainly related to the following areas:

Environment variables Display JVM parameters display Java System Properties display garbage collection display Java lock display Java thread display to generate Java, heap and system dump control garbage collection log

We will explain the use of Wrkjvmjob in the later chapters.

Wrkjvmjob Basic Operations

There are jobs in the parameters of the Wrkjvmjob command, as well as options. When the parameters of a job can uniquely determine a job, the option will work on the job, otherwise this option will be ignored. For example, the following command can go directly to the garbage collection Information window of the 044210 job.

Wrkjvmjob JOB (044210/QSYS/QSVRMSERMD) OPTION (*GC)

Specific parameter descriptions, you can use the F1 function keys to refer to the Wrkjvmjob help information. On IBM I, this is usually a very effective approach.

By default, Wrkjvmjob will enumerate all the J9 jobs in the system, as follows:

Figure 1. Wrkjvmjob List all J9 jobs

In this window we can see that there are two J9 jobs in the system, including job name, job number, user name and so on. Through the function key F11 you can see more detailed information about each job, such as number of threads, process numbering, subsystems, and so on.