This appendix describes environment variables and system properties that can be useful for troubleshooting problems with the Java HotSpot VM.
This appendix contains the following sections:
This variable shows the directory where the Java Development Kit (JDK) software is installed.
In many environments, the command line is not readily accessible to start the application with the necessary command-line options.
This often happens with applications that use embedded VMs (meaning they use the Java Native Interface (JNI) Invocation API to start the VM), or where the startup is deeply nested in scripts. In these environments the
JAVA_TOOL_OPTIONS environment variable can be useful to augment a command line.
When this environment variable is set, the
JNI_CreateJavaVM function (in the JNI Invocation API), the
JNI_CreateJavaVM function adds the value of the environment variable to the options supplied in its
In some cases, this option is disabled for security reasons. For example, on the Oracle Solaris operating system, this option is disabled when the effective user or group ID differs from the real ID.
This environment variable allows you to specify the initialization of tools, specifically the launching of native or Java programming language agents using the
This variable can also be used to augment the command line with other options for diagnostic purposes. For example, you can supply the
-XX:OnError option to specify a script or command to be executed when a fatal error occurs.
Because this environment variable is examined at the time, that the
JNI_CreateJavaVM function is called, it cannot be used to augment the command line with options that would normally be handled by the launcher, for example, VM selection using the
-client option or the
This system property controls whether the security system of the Java Runtime Environment (JRE) prints trace messages during execution.
This option can be useful when diagnosing an issue involving a security manager when a
SecurityException is thrown.
java.security.debug property can have the following values:
The following additional options can be specified with the
Include stack trace.
Dump all domains in context.
Before throwing an exception, dump the stack and domain that did not have permission.
Print the JAR verification information.
Print the permissions that
For example, to print all
checkPermission results and trace all domains in context, set the
java.security.debug property to
access,stack. To trace access failures, set the property to
The following example shows the output of a
$ java -Djava.security.debug="access,failure" MyApp access denied (java.net.SocketPermission server.foobar.com resolve ) java.lang.Exception: Stack trace at java.lang.Thread.dumpStack(Thread.java:1158) at java.security.AccessControlContext.checkPermission (AccessControlContext.java:253) at java.security.AccessController.checkPermission(AccessController.java:427) at java.lang.SecurityManager.checkPermission(SecurityManager.java:532) at java.lang.SecurityManager.checkConnect(SecurityManager.java:1031) at java.net.InetAddress.getAllByName0(InetAddress.java:1117) at java.net.InetAddress.getAllByName0(InetAddress.java:1098) at java.net.InetAddress.getAllByName(InetAddress.java:1061) at java.net.InetAddress.getByName(InetAddress.java:958) at java.net.InetSocketAddress.<init>(InetSocketAddress.java:124) at java.net.Socket.<init>(Socket.java:178) at MyApp.main(MyApp.java:7)
To know more about the
java.security.debug system property, see the Troubleshooting Security in the Java Platform, Standard Edition Security Developer's Guide.