IBM User Guide for Java V7 on Windows > Troubleshooting and support > Using diagnostic tools > Shared classes diagnostic data > Understanding shared classes diagnostics output

printAllStats utility

The printAllStats utility is a suboption of -Xshareclasses, optionally taking a cache name using name=<name>. This utility lists the cache contents in order, providing as much diagnostic information as possible. Because the output is listed in chronological order, you can interpret it as an "audit trail" of cache updates. Because it is a cache utility, the JVM displays the information about the cache specified or the default cache and then exits.

Each JVM that connects to the cache receives a unique ID. Each entry in the output is preceded by a number indicating the JVM that wrote the data.

Classpaths

1: 0x2234FA6C CLASSPATH
        C:\myJVM\sdk\jre\lib\vm.jar
        C:\myJVM\sdk\jre\lib\core.jar
        C:\myJVM\sdk\jre\lib\charsets.jar
        C:\myJVM\sdk\jre\lib\graphics.jar
        C:\myJVM\sdk\jre\lib\security.jar
        C:\myJVM\sdk\jre\lib\ibmpkcs.jar
        C:\myJVM\sdk\jre\lib\ibmorb.jar
        C:\myJVM\sdk\jre\lib\ibmcfw.jar
        C:\myJVM\sdk\jre\lib\ibmorbapi.jar
        C:\myJVM\sdk\jre\lib\ibmjcefw.jar
        C:\myJVM\sdk\jre\lib\ibmjgssprovider.jar
        C:\myJVM\sdk\jre\lib\ibmjsseprovider2.jar
        C:\myJVM\sdk\jre\lib\ibmjaaslm.jar
        C:\myJVM\sdk\jre\lib\ibmjaasactivelm.jar
        C:\myJVM\sdk\jre\lib\ibmcertpathprovider.jar
        C:\myJVM\sdk\jre\lib\server.jar
        C:\myJVM\sdk\jre\lib\xml.jar

This output indicates that JVM 1 caused a class path to be stored at address 0x2234FA6C in the cache. The class path contains 17 entries, which are listed. If the class path is stored using a given partition or modification context, this information is also shown.

ROMClasses

1: 0x2234F7DC ROMCLASS: java/lang/Runnable at 0x213684A8
        Index 1 in class path 0x2234FA6C

This output indicates that JVM 1 stored a class called java/lang/Runnable in the cache. The metadata about the class is stored at address 0x2234F7DC, and the class itself is written to address 0x213684A8. The output also indicates the class path against which the class is stored, and from which index in that class path the class was loaded. In the example, the class path is the same address as the one listed in the Classpath example. If a class is stale, it has !STALE! appended to the entry. If the ROMClass is stored using a given partition or modification context, this information is also shown.

AOT methods

1: 0x540FBA6A AOT: loadConvert
        for ROMClass java/util/Properties at 0x52345174

This output indicates that JVM 1 stored AOT compiled code for the method loadConvert() in java/util/Properties. The ROMClass address is the address of the ROMClass that contains the method that was compiled. If an AOT method is stale, it has !STALE! appended to the entry.

URLs and Tokens

URLs and Tokens are displayed in the same format as class paths. A URL is effectively the same as a class path, but with only one entry. A Token is in a similar format, but it is a meaningless string passed to the Java™ Helper API.

ZipCache

1: 0x042FE07C ZIPCACHE: luni-kernel.jar_347075_1272300300_1 Address: 0x042FE094 Size: 7898
1: 0x042FA878 ZIPCACHE: luni.jar_598904_1272300546_1 Address: 0x042FA890 Size: 14195
1: 0x042F71F8 ZIPCACHE: nio.jar_405359_1272300546_1 Address: 0x042F7210 Size: 13808
1: 0x042F6D58 ZIPCACHE: annotation.jar_13417_1272300554_1 Address: 0x042F6D70 Size: 1023

The first line in the output indicates that JVM 1 stored a zip entry cache called luni-kernel.jar_347075_1272300300_1 in the shared cache. The metadata for the zip entry cache is stored at address 0x042FE07C. The data is written to the address 0x042FE094, and is 7898 bytes in size. Storing zip entry caches for bootstrap jar files is controlled by the -Xzero:sharebootzip sub option, which is enabled by default. The full -Xzero option is not enabled by default.

JIT data

1: 0xD6290368 JITPROFILE: getKeyHash Signature: ()I Address: 0xD55118C0
for ROMClass java/util/Hashtable$Entry at 0xD5511640.
2: 0xD6283848 JITHINT: loadClass Signature: (Ljava/lang/String;)Ljava/lang/Class; Address: 0xD5558F98
for ROMClass com/ibm/oti/vm/BootstrapClassLoader at 0xD5558AE0.

The JIT stores data in the shared classes cache in the form of JITPROFILE and JITHINT entries to improve runtime performance. These outputs expose the content of the shared cache and can be useful for diagnostic purposes.

Parent: Understanding shared classes diagnostics output

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