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Recent changes to the information in the V1.4.1 Diagnostics Guide
These changes are listed in the order in which they became available. The most recent addition is at the bottom.
Correction to -X options in v1.4.1
In Chapter 2 of the v1.4.1 Diagnostics Guide, in the section called "Avoiding fragmentation", there is information about the -Xp and -Xk options. Ignore this information because the -Xp and -Xk options are not included in the JVM.
Path length limitation on Windows SDKs
This change applies to all releases.
The Windows v1.4.1 SDK does not support files that have path lengths greater than 255 characters. For more information, see SUNBUG ID: 4403166, which you can see at:  http://developer.java.sun.com/developer/bugParade/bugs/4403166.html.
Changes to -Xtgc options
To enable GC trace options on SDK v1.4.1 and later, use the property –Dibm.dg.trace.print=<value> instead of the command-line option –Xtgc<n>.
On page 22 in the v1.4.1 Diagnostics Guide (DG):
–Xtgc2 should read –Dibm.dg.trc.print=st_verify.
On page 456 in the v1.4.1 DG and page 454 in the v1.4.2 DG:
–Xtgc8388608 should read –Dibm.dg.trc.print=st_concurrent_shadow_heap.
Addition to system property command-line parameters
-Dibm.stream.nio={true|false}
From v1.4.1 onwards, by default the IO converters are used. This option addresses the ordering of IO and NIO converters. When this option is set to true, the NIO converters are used instead of the IO converters.
Corrections to :Xgccon option information
:Xgccon is sometimes incorrectly spelled ":Xgcon". In the v1.4.1 SR1 guide, see pages 308 and 309. Also, in the section "verbosegc output from a concurrent mark collection with :Xgcon", the statement "The addition of the :Xgccon parameter to the verbosegc command" should read "verbose" not "verbosegc".
Correction to ulimit options
The "Linux problem determination" chapter contains a table describing the ulimit options. The ulimit -p option is documented incorrectly. -p does not control the number of user processes; it is related to the size of pipes. -u is the option related to the number of processes.
Addition of -Dsun system property command-line parameters
-Dsun.net.client.defaultConnectTimeout=<value in milliseconds>
This property specifies the default value for the connect timeout for the protocol handlers used by the java.net.URLConnection class. The default value set by the protocol handlers is -1, which means there is no timeout set.
When a connection is made by an applet to a server and the server does not respond properly, the applet might appear to hang and might also cause the browser to hang. This apparent hang occurs because there is no network connection timeout. To avoid this problem, the Java Plug-in has added a default value to the network timeout of 2 minutes for all HTTP connections. You can override the default by setting this property.
-Dsun.net.client.defaultReadTimeout=<value in milliseconds>
This property specifies the default value for the read timeout for the protocol handlers used by the java.net.URLConnection class when reading from an input stream when a connection is established to a resource.
The default value set by the protocol handlers is -1, which means there is no timeout set.
Correction to AF actions in the "Garbage Collector diagnostics" chapter
In the section "verbosegc output from an allocation failure", the list of possible AF actions should begin at 0, not 1.
Additional z/OS environment variable
In the "z/OS environment variables" section of the "Environment variables" appendix, add this environment variable:
JAVA_LOCAL_TIME
The z/OS JVM does not look at the offset part of the TZ environment variable and will therefore incorrectly show the local time. Where local time is not GMT, you can set the environment variable JAVA_LOCAL_TIME to display the correct local time as defined by TZ.
Error in JNI mode flag usage
In Chapter 6 about JNI, under the Using the mode flag heading, the description of the possible settings are incorrect. If used, these descriptions might introduce errors into a program.
The possible setting of the mode flag are:
- 0
- Update the data on the Java heap, free the copy.
- JNI_COMMIT
- Update the data on the Java heap, do not free the copy.
- JNI_ABORT
- Do not update the data on the Java heap, free the copy.
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