> Openjdk Runtime
> Openjdk Runtime Options
Openjdk Runtime Options
During a safepoint the Threads_lock is used to block any threads that were running, with the VMThread finally releasing the Threads_lock after the VM operation has been performed. It does this by starting a Java runtime environment, loading a specified class, and invoking that class's main method. By default, the maximum bytecode size of a trivial method is set to 6 bytes: -XX:MaxTrivialSize=6 -XX:+OptimizeStringConcat Enables the optimization of String concatenation operations. The Java SE class loader hierarchy searches the bootstrap class loader, the extension class loader and the system class loader in that order. http://opinfos.com/openjdk-runtime/openjdk-runtime.html
These are developer options used for tuning specific areas of the Java HotSpot Virtual Machine operation that often have specific system requirements and may require privileged access to system configuration parameters. With one argument not ending in "...", the switch enables assertions in the specified class. The JVM uses CTRL_BREAK_EVENT to perform thread dumps. Additional java options for running test classes.
Class initialization runs the static initializers, and initializers for static fields. The maximum code cache size should not be less than the initial code cache size; see the option -XX:InitialCodeCacheSize. By default, this parameter is set to false (dump file on exit is not generated).
Use the PredictedClassLoadCount flag if your application loads a lot of classes, and especially if class.forName() is used heavily. For better performance, set the Xms and Xmx options to the same value. 3 If the error is a PermGenSpace error, set the XX:PermSize and XX:MaxPermSize options to higher values in This is called class loader delegation. Openjdk Source TESTSRCPATH test.src.path The path containing the TESTSRC directory, and any library directories that may have been specified with @library.
For options that require an argument, the argument may be separated from the option name by a space, a colon (:), or an equal sign (=), or the argument may directly Jtreg -nativepath This is necessary both for coordinating the interactions of threads, and for providing useful debugging information if things go wrong. If the size is too large, then only full garbage collections will be performed, which can take a long time to complete. The -Xbatch flag disables background compilation so that compilation of all methods proceeds as a foreground task until completed. -Xbootclasspath:bootclasspath Specify a colon-separated list of directories, JAR archives, and ZIP archives
This could cause OutOfMemoryError to be thrown in some applications. -Xincgc Enable the incremental garbage collector. Java Hotspot Download Append the letter k or K to indicate kilobytes, m or M to indicate megabytes, g or G to indicate gigabytes. See the Adding/Modifying JVM Command Line Options section below. For jar files, the usual preference is to specify version requirements in the jar file manifest rather than on the command line.
This value must be a multiple of 1024 and greater than 2 MB. https://linux.die.net/man/1/java-java-1.7.0-openjdk This is subject to change in a future release. Openjdk Options Since JDK 6, a stack trace will be included in the error message. Openjdk Hotspot For a long-form options, the argument may be separated from the option name by either white space or '='.
The default is to use the same JDK version (provided by JAVA_HOME) for both the harness and the tests, and for each test to run in its own JVM. -avm | this content By default, the depth is set to 64 method calls. After preparing all of the VM state (such as thread-local storage and allocation buffers, synchronization objects and so forth) the native thread is started. The following examples show how to set the size of allocated memory to 6 MB using various units: -Xms6291456 -Xms6144k -Xms6m If you do not set this option, then the initial Hotspot Source Code
Specifically, the Java Virtual Machine validates the parameters passed to the JNI function as well as the runtime environment data before processing the JNI request. The star means prefix match, the plus sign means this version or greater, and the ampersand means the logical anding of the two version-ranges. For more information, see HotSpot Ergonomics Examples: -Xmx83886080 -Xmx81920k -Xmx80m On Solaris 7 and Solaris 8 SPARC platforms, the upper limit for this value is approximately 4000m minus overhead amounts. weblink For example, to run the MyClass application with assertions enabled in package com.wombat.fruitbat (and any subpackages) but disabled in class com.wombat.fruitbat.Brickbat, use the following command: java -ea:com.wombat.fruitbat... -da:com.wombat.fruitbat.Brickbat MyClass -disablesystemassertions -dsa
Example: -XX:StartFlightRecording=name=test,filename=D:\test.jfr,dumponexit=true duration=time Specifies the duration of the recording. Java Options If you give multiple values, you may need to enclose them in quotes, depending on the shell you use. Refer to Java Archive (JAR) Files. -javaagent:jarpath[=options] Load a Java programming language agent, see java.lang.instrument. -verbose -verbose:class Display information about each class loaded. -verbose:gc Report on each garbage collection event. -verbose:jni
Developers are encouraged to use this flag when developing new code because the stricter checks will become the default in future releases of the Java application launcher. -Xnoclassgc Disable class garbage
The following example shows how to set the number of loaded cache lines to 5: -XX:AllocatePrefetchLines=5 Only the Java HotSpot Server VM supports this option. -XX:AllocatePrefetchStepSize=size Sets the step size (in Once the java main method completes, its very important to check and clear any pending exceptions that may have occurred and also pass back the exit status, the exception is cleared The -Xloggc option overrides -verbose:gc if both are given with the same java command. Jvm Large pages are enabled by default on Solaris. -XX:+UseParallelOldGC Enables the parallel garbage collectors, which are optimized for throughput and average response time. Notes The -version:release command line option places
The performance benefits offered by the Java HotSpot VMs' adaptive compiler will not be present in this mode. -Xbatch Disable background compilation. Verbose Options These options control the amount of output written to the console while running tests. -v | -v: | -verbose | -verbose: Increase the amount of output written to the With biased locking, in the best case these operations are essentially free of cost. http://opinfos.com/openjdk-runtime/openjdk-runtime-environment-icedtea-2-5-4.html If the size for the young generation is too small, then a lot of minor garbage collections will be performed.
The dump file is written to the location defined by the filename parameter. In addition, tools currently supporting a -classpath option should support the new-style long form option as equivalent: --class-path Given the existing support for -cp as a short form for -classpath, Normally the VM will compile the method as a background task, running the method in interpreter mode until the background compilation is finished. GC is performed in this region more often than in other regions.
Otherwise, the files may be described by one or more of the following values: none Do not retain any of the files generated by each test pass Retain files generated by With no arguments, disableassertions or -da disables assertions. This is subject to change in a future release. pack200: -g, --no-gzip, --gzip, --version Even the options used to show command-line help vary between different JDK tools, with -help, -?, --help being amongst the alternatives.
The performance benefits offered by the Java HotSpot VMs' adaptive compiler will not be present in this mode. -Xbatch Disable background compilation. By default, this option is disabled and constant pool resolutions are not traced. -XX:+TraceClassUnloading Enables tracing of classes as they are unloaded. Checks to make sure the JNI version is supported, and the ostream is initialized for gc logging. When you use the -jar option, the specified JAR file is the source of all user classes, and other class path settings are ignored.
To explicitly enable assertions in specific packages or classes, use the -enableassertions (-ea) option.