When launched in a placement group, select EC2 instances can utilize up to 10 Gbps for single-flow traffic.
TypeScript Language team blog. You can identify those by running the jdeps tool with the --jdk-internals option. For performance reasons, JDK 9 does not issue warnings for illegal static-access operations. Enables the option to prevent the java command from running a Java application if any of these directories exists and isn't empty:. Disables the Compact Strings feature. By default, this option is enabled.
For Java Strings containing at least one multibyte character: In the unexpected event where a performance regression is observed in migrating from Java SE 8 to Java SE 9 and an analysis shows that Compact Strings introduces the regression. Adds directives from a file to the directives stack when a program starts. See Compiler Directives and the Command Line. Sets the number of parallel marking threads. Disables the mechanism that lets tools attach to the JVM.
By default, this option is disabled, meaning that the attach mechanism is enabled and you can use diagnostics and troubleshooting tools such as jcmd , jstack , jmap , and jinfo. Specifies the path and file name to which error data is written when an irrecoverable error occurs. The following example shows how to set the error log file to C: Enables automatic failover to the old verifier when the new type checker fails.
You can enable it for classes with older versions of the bytecode. This is a commercial feature that requires that you also specify the -XX: Sets the parameters that control the behavior of JFR. This is a commercial feature that works in conjunction with the -XX: This was a change made in JDK 8u Specifies the total amount of primary memory in bytes used for data retention. By default, the size is set to bytes. Specify the amount of data written to the log file by JFR.
Specifies the maximum size in bytes of the data chunks in a recording. By default, the maximum size of data chunks is set to 12 MB. Specifies the repository a directory for temporary disk storage. By default, the system's temporary directory is used. Specifies whether thread sampling is enabled. Thread sampling occurs only if the sampling event is enabled along with this parameter.
By default, this parameter is enabled. Stack depth for stack traces by JFR. By default, the depth is set to 64 method calls. The maximum is , and the minimum is 1. Specifies the per-thread local buffer size in bytes. Higher values for this parameter allow more data gathering without contention to flush it to the global storage. It can increase an application footprint in a thread-rich environment. By default, the local buffer size is set to 5 KB. If false, instrumentation will be added when event classes are loaded.
By default it is true. Sets the Java heap occupancy threshold that triggers a marking cycle. The default occupancy is 45 percent of the entire Java heap. Sets the maximum size in bytes for large pages used for the Java heap. The size argument must be a power of 2 2, 4, 8, 16, and so on. By default, the size is set to 0, meaning that the JVM chooses the size for large pages automatically. Sets the maximum total size in bytes of the java.
By default, the size is set to 0, meaning that the JVM chooses the size for NIO direct-buffer allocations automatically. Disables the attempt to set the soft limit for the number of open file descriptors to the hard limit. By default, this option is enabled on all platforms, but is ignored on Windows.
The only time that you may need to disable this is on Mac OS, where its use imposes a maximum of , which is lower than the actual system maximum. Sets a target value for the desired maximum pause time.
The default value is milliseconds. Specifies the mode for tracking JVM native memory usage. Instructs not to track JVM native memory usage. In addition to tracking memory usage by JVM subsystems, track memory usage by individual CallSite , individual virtual memory region and its committed regions. Sets the memory alignment of Java objects in bytes.
By default, the value is set to 8 bytes. The specified value should be a power of 2, and must be within the range of 8 and inclusive. This option makes it possible to use compressed pointers with large Java heap sizes. As the alignment value increases, the unused space between objects also increases. As a result, you may not realize any benefits from using compressed pointers with large Java heap sizes. Sets a custom command or a series of semicolon-separated commands to run when an irrecoverable error occurs.
If the string contains spaces, then it must be enclosed in quotation marks. The following example shows how the -XX: OnError option can be used to run the userdump. This example assumes that the path to the userdump. Sets a custom command or a series of semicolon-separated commands to run when an OutOfMemoryError exception is first thrown. For an example of a command string, see the description of the -XX: Sets the value of the STW worker threads.
Sets the value of n to the number of logical processors. The value of n is the same as the number of logical processors up to a value of 8.
If enabled, saves jstat binary data when the Java application exits. Use the jstat command to display the performance data contained in this file as follows:. Enables printing of ergonomically selected JVM flags that appeared on the command line. It can be useful to know the ergonomic values set by the JVM, such as the heap space size and the selected garbage collector. Enables printing of collected native memory tracking data at JVM exit when native memory tracking is enabled see -XX: Decreases the amount of access control checks in the verifier.
This is a commercial feature that requires you to also specify the -XX: Sets the parameter that controls the sampling interval for Resource Management measurements, in milliseconds. This option can be used only when Resource Management is enabled that is, the -XX: See Application Class Data Sharing. Specifies the text file that contains the names of the class files to store in the class data sharing CDS archive.
For example, to specify the classes java. Main , create a text file that contains the following two lines:. The class files that you specify in this text file should include the classes that are commonly used by the application.
They may include any classes from the application, extension, or bootstrap class paths. Enables the display of a dialog box when the JVM experiences an irrecoverable error.
This prevents the JVM from exiting and keeps the process active so that you can attach a debugger to it to investigate the cause of the error. By default, this option is disabled. Starts a JFR recording for the Java application. This option is equivalent to the JFR. You can set the following parameters when starting a JFR recording:. Specifies the delay between the Java application launch time and the start of the recording.
Append s to specify the time in seconds, m for minutes, h for hours, or d for days for example, specifying 10m means 10 minutes. Specifies the duration of the recording. Append s to specify the time in seconds, m for minutes, h for hours, or d for days for example, specifying 5h means 5 hours.
Specifies the maximum age of disk data to keep for the default recording. Append s to specify the time in seconds, m for minutes, h for hours, or d for days for example, specifying 30s means 30 seconds. By default, the maximum age is set to 15 minutes 15m. Specifies the maximum size in bytes of disk data to keep for the default recording. Specifies the path and name of the event settings file of type JFC. By default, the default. Sets the Java thread stack size in kilobytes.
Use of a scaling suffix, such as k , results in the scaling of the kilobytes value so that -XX: Enables the use of commercial features.
By default, this option is disabled and the JVM runs without the commercial features. Enables application class data sharing AppCDS. This is also an experimental feature; it may change in future releases. Disables the use of biased locking. Some applications with significant amounts of uncontended synchronization may attain significant speedups with this flag enabled, but applications with certain patterns of locking may see slowdowns.
Disables the use of compressed pointers. By default, this option is enabled, and compressed pointers are used when Java heap sizes are less than 32 GB. When this option is enabled, object references are represented as bit offsets instead of bit pointers, which typically increases performance when running the application with Java heap sizes of less than 32 GB. This option works only for bit JVMs. Handles large log files. This option must be used with -Xloggc: The number of files must be greater than or equal to 1.
The default is 1. The number can be in the form of number M or number K. The default is set to K. This option is the equivalent of specifying -XX: This option is disabled by default. UseTransparentHugePages if you want this behavior.
Enables the use of large page memory. Enables issuing of membars on thread-state transitions. Enables the perfdata feature. This option is enabled by default to allow JVM monitoring and performance testing. To disable the perfdata feature, specify -XX: Enables the use of large pages that can dynamically grow or shrink. You may encounter performance problems with transparent huge pages as the OS moves other pages around to create huge pages; this option is made available for experimentation.
Enables installation of signal handlers by the application. Allows user to specify VM options in a file, for example, java -XX: Enables the use of aggressive performance optimization features. Sets the number of lines to prefetch ahead of the instance allocation pointer. By default, the number of lines to prefetch is set to Sets the size in bytes of the prefetch distance for object allocation.
Memory about to be written with the value of new objects is prefetched up to this distance starting from the address of the last allocated object.
Each Java thread has its own allocation point. Negative values denote that prefetch distance is chosen based on the platform. Positive values are bytes to prefetch. The default value is set to Sets the prefetch instruction to prefetch ahead of the allocation pointer. Possible values are from 0 to 3. The actual instructions behind the values depend on the platform. By default, the prefetch instruction is set to Sets the number of cache lines to load after the last object allocation by using the prefetch instructions generated in compiled code.
The default value is 1 if the last allocated object was an instance, and 3 if it was an array. Sets the step size in bytes for sequential prefetch instructions. By default, the step size is set to 16 bytes:. Sets the generated code style for prefetch instructions. The style argument is an integer from 0 to Use the thread-local allocation block TLAB watermark pointer to determine when prefetch instructions are executed. This option is enabled by default.
To disable background compilation, specify -XX: Sets the number of compiler threads to use for compilation. By default, the number of threads is set to 2 for the server JVM, to 1 for the client JVM, and it scales to the number of cores if tiered compilation is used. The following example shows how to set the number of threads to Specifies a command to perform on a method.
For example, to exclude the indexOf method of the String class from being compiled, use the following:. If the method is specified without the signature, then the command isapplied to all methods with the specified name.
However, you can also specify the signature of the method in the class file format. In this case, you should enclose the arguments in quotation marks, because otherwise the shell treats the semicolon as a command end.
For example, if you want to exclude only the indexOf String method of the String class from being compiled, use the following:. For example, to exclude all indexOf methods in all classes from being compiled, use the following:. The commas and periods are aliases for spaces, making it easier to pass compiler commands through a shell. You can pass arguments to -XX: CompileCommand using spaces as separators by enclosing the argument in quotation marks:.
Note that after parsing the commands passed on the command line using the -XX: CompileCommand options, the JIT compiler then reads commands from the.
You can add commands to this file or specify a different file using the -XX: To add several commands, either specify the -XX: The following commands are available:. Sets a breakpoint when debugging the JVM to stop at the beginning of compilation of the specified method. Excludes all methods from compilation except for the specified method. As an alternative, you can use the -XX: CompileOnly option, which lets you specify several methods.
Excludes compilation logging with the -XX: By default, logging is performed for all compiled methods. Passes a JIT compilation option to the specified method in place of the last argument option.
The compilation option is set at the end, after the method name. For example, to enable the BlockLayoutByFrequency option for the append method of the StringBuffer class, use the following:. Instructs not to print the compile commands. By default, the commands that you specify with the - XX: CompileCommand option are printed; for example, if you exclude from compilation the indexOf method of the String class, then the following is printed to standard output:.
You can suppress this by specifying the -XX: Sets the file from which JIT compiler commands are read. Each line in the command file represents a command, a class name, and a method name for which the command is used.
For example, this line prints assembly code for the toString method of the String class:. Sets the list of methods separated by commas to which compilation should be restricted. Only the specified methods are compiled. Specify each method with the full class name including the packages and subpackages.
For example, to compile only the length method of the String class and the size method of the List class, use the following:. Sets the number of interpreted method invocations before compilation. By default, in the server JVM, the JIT compiler performs 10, interpreted method invocations to gather information for efficient compilation. For the client JVM, the default setting is 1, invocations. This option is ignored when tiered compilation is enabled; see the option -XX: The following example shows how to set the number of interpreted method invocations to 5, You can completely disable interpretation of Java methods before compilation by specifying the -Xcomp option.
Provides unified control of first compilation. This option controls when methods are first compiled for both the tiered and the nontiered modes of operation. Setting CompileThresholdScaling to a value less than 1.
Setting CompileThresholdScaling to 0 is equivalent to disabling compilation. Enables the use of escape analysis. To disable the use of escape analysis, specify -XX: Sets the initial code cache size in bytes.
The default value is set to KB. The following example shows how to set the initial code cache size to 32 KB:. This option is enabled by default to increase performance.
To disable method inlining, specify -XX: Sets the maximum code size in bytes for compiled methods that should be inlined. Only compiled methods with the size smaller than the specified size is inlined. By default, the maximum code size is set to bytes:.
Enables logging of compilation activity to a file named hotspot. You can specify a different log file path and name using the -XX: You can enable verbose diagnostic output with a message printed to the console every time a method is compiled by using the -XX: Sets the maximum bytecode size in bytes of a method to be inlined.
By default, the maximum bytecode size is set to 35 bytes:. Sets the maximum number of nodes to be used during single method compilation. By default, the maximum number of nodes is set to 65, A nonmethod code segment containing nonmethod code, such as compiler buffers and the bytecode interpreter. This code type stays in the code cache forever. This flag is used only if —XX: Sets the size in bytes of the code segment containing nonprofiled methods.
Sets the maximum bytecode size in bytes of a trivial method to be inlined. By default, the maximum bytecode size of a trivial method is set to 6 bytes:. Enables the optimization of String concatenation operations. To disable the optimization of String concatenation operations, specify -XX: Sets the size in bytes of the code segment containing profiled methods.
Enables verbose diagnostic output from the JVM by printing a message to the console every time a method is compiled.
You can also log compilation activity to a file by using the -XX: Enables printing of inlining decisions. Sets the maximum code cache size in bytes for JIT-compiled code.
The default maximum code cache size is MB; if you disable tiered compilation with the option -XX: This option has a limit of 2 GB; otherwise, an error is generated. This option is equivalent to -Xmaxjitcodesize.
If a number of aborted transactions becomes greater than this ratio, then the compiled code is deoptimized. This ratio is used when the -XX: The default value of this option is Enables segmentation of the code cache. The feature is enabled by default if tiered compilation is enabled -XX: ICache is an instruction cache in theCPU.
The implementation of the code cache can be found in the file: Forces stack scanning of active methods to aggressively remove unused code when only the given percentage of the code cache is free. Specifies the number of times that the RTM locking code is retried, when it is aborted or busy, before falling back to the normal locking mechanism. The default value for this option is 5.
UseRTMLocking option must be enabled. Disables the use of tiered compilation. Flags that control intrinsics now require the option -XX: For example, to enable hardware AES, use the following flags:.
Enables flushing of the code cache before shutting down the compiler. To disable flushing of the code cache before shutting down the compiler, specify -XX: Enables checking if the card is already marked before updating the card table. It should be used only on machines with multiple sockets, where it increases the performance of Java applications that rely on concurrent operations.
FMA intrinsics are generated for the java. Autotunes RTM locking depending on the abort ratio. This ratio is specified by the -XX: If the number of aborted transactions exceeds the abort ratio, then the method containing the lock is deoptimized and recompiled with all locks as normal locks. Generates Restricted Transactional Memory RTM locking code for all inflated locks, with the normal locking mechanism as the fallback handler.
RTM is part of Intel's TSX, which is an x86 instruction set extension and facilitates the creation of multithreaded applications. If no conflict is found when running the transaction, then the memory and register modifications are committed together at the XEND instruction.
RTM requires that a fallback set of operations be specified in case a transaction aborts or fails. RTM improves performance for highly contended locks with low conflict in a critical region which is code that must not be accessed by more than one thread concurrently. Coarse-grain locking is the strategy of holding locks for long periods to minimize the overhead of taking and releasing locks, while fine-grained locking is the strategy of trying to achieve maximum parallelism by locking only when necessary and unlocking as soon as possible.
Also, for lightly contended locks that are used by different threads, RTM can reduce false cache line sharing, also known as cache line ping-pong. This occurs when multiple threads from different processors are accessing different resources, but the resources share the same cache line.
As a result, the processors repeatedly invalidate the cache lines of other processors, which forces them to read from main memory instead of their cache. This feature is applicable only when using the sun. Sun provider for SHA operations.
To disable only a particular SHA intrinsic, use the appropriate corresponding option. Enables intrinsics for SHA-1 crypto hash function.
Enables the transformation of scalar operations into superword operations. Superword is a vectorization optimization. To disable the transformation of scalar operations into superword operations, specify -XX: These java options provide the ability to gather system information and perform extensive debugging. Enables additional dtrace tool probes that affect the performance. By default, this option is disabled and dtrace performs only standard probes. OutOfMemoryError exception is thrown.
You can explicitly set the heap dump file path and name using the -XX: The following example shows how to set the heap dump file to C: Sets the path and file name to where log data is written. The following example shows how to set the log file to C: Setting this option is equivalent to running the jmap -histo command, or the jcmd pid GC. Enables printing of java. Setting this option is equivalent to running the jstack -l command or the jcmd pid Thread. Prints the range specified and allows automatic testing of the values.
Unlocks the options intended for diagnosing the JVM. Enables Java heap optimization. This sets various parameters to be optimal for long-running jobs with intensive memory allocation, based on the configuration of the computer RAM and CPU. Enables touching of every page on the Java heap during JVM initialization. This gets all pages into memory before entering the main method.
The option can be used in testing to simulate a long-running system with all virtual memory mapped to physical memory. By default, this option is disabled and all pages are committed as JVM heap space fills. Enables class unloading when using the concurrent mark-sweep CMS garbage collector. Sets the percentage of time 0 to used to weight the current sample when computing exponential averages for the concurrent collection statistics.
Sets the percentage 0 to of time between minor collections that the CMS collector is allowed to run. The default value is The default value is 0. Sets the percentage 0 to used to add conservatism when computing the duty cycle. Using the command prompt, create an empty project folder where you want to create the project in.
Below is the package configuration file. Below is the typescript configuration file. These options will do the following: Below is the webpack configuration file. It contains all the information to compile and bundle the source code. This ends part one of the blog post. The next post will go over the core file and folder structure of the application. Your email address will not be published.