This Refcard will help Java developers working with multi-threaded programs to understand core concurrency concepts and how to apply them. Overview the. This Refcard covers JVM internals, class loading (updated to reflect the new Metaspace in Java 8), garbage collection, troubleshooting, monitoring, concurrency. This Refcard focuses on the design, deployment, service discovery, and management of Java applications on the open-source project called Docker so that you.

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Java Performance Optimization

Most of the methods of the ExecutorService use Future as a return type. Deadlock A deadlock occurs when there is more than one thread, each waiting for a resource held by another, such that a cycle of resources and acquiring threads is formed.

Livelock and thread starvation Livelock occurs when threads spend all of their time negotiating access to a resource or detecting and avoiding deadlock such that no thread actually makes progress.

Using AtomicXXX classes, it is possible to implement an atomic check-then-act operation:. Services should also track the progression of both business and operational metrics. The more we can do upfront to support remediation in those waning and critical seconds, minutes, and hours after a production outage, the better.

Otherwise, all files are extracted.

Java EE 7 Reference Card at DZone

It is important to realize that no GC policy can save your application from an inadequate Java heap sizing. Event which consists of values that indicate the start of an object, end of an object, and other similar events. Concept Description Atomicity An atomic operation is one which is executed in an all or nothing fashion, therefore partial state is impossible.


As a starting point, here are some recommended guidelines: This Refcard covers JVM internals, class loading updated to reflect the new Metaspace in Java 8garbage collection, troubleshooting, monitoring, concurrency, and more. Always wait inside a loop that checks the condition being waited on — this addresses the timing issue if another thread satisfies the condition before the wait begins.

Unexpected exception handling Threads can specify an UncaughtExceptionHandler that will receive a notification reccard any uncaught exception that causes a thread to abruptly terminate.

Instead, use Thread interrupt or a volatile flag to indicate to a thread what it should do. The HotSpot G1 collector is designed to meet user-defined garbage collection GC pause time goals with high probability, while achieving high throughput.

Java 8 Performance Optimization – DZone Refcard Update ~ Java EE Support Patterns

Monitor is acquired by several threads with no contention. In the “generalized” for loop, the expression after the: Services should expose their own health endpoints, metadata about the service itself, logs, threadumps, configuration and refcwrd information, and whatever else could be operationally useful. JSR Most enterprise applications will need to deal with persistent data, and interaction with relational databases can be a tedious and difficult endeavor.

Each format specifier has the following form. In order to provide efficient garbage collection, the Heap is essentially divided into sub areas. The Revcard of Thread start happens before any action in this thread.

Automation at the platform and application tiers support this velocity.

Core Java Concurrency

Long-term solutions normally involve resolving memory leaks and tuning your application class metadata footprint The usage of Java pro ler tools and JVM Heap Dump analysis will greatly help you achieve such goals.

Similar to lock contention troubleshooting, it is recommended to use techniques such as thread dump analysis as a starting point. Each Netflix Hystrix circuit breaker exposes a server-sent event-based stream of status information about the Netflix Hystrix on that node.


The size is a value in bytes.

Use a TreeMap to traverse in sort order requires that key type is comparable for Map. Elements can only be removed when their delay has passed and are removed in the order of the oldest expired item. Metrics can be overwhelming, and so it makes sense to publish collected metrics to time-series databases that support analytics and refcad. For example, jar cvfC myprog.

Unix or ; Windows. Annotation that javaa the application the ability to declaratively control transaction boundaries refard CDI-managed beans, as well as classes defined as managed beans.

It provides concurrent access along with sorted map functionality similar to TreeMap. If you omit a break, processing continues with the next case. Distributed transactions are a stop-the-world approach to state synchronization; that is the worst possible outcome in a distributed system. The following are examples of beans that would be automatically enabled for injection using default settings.

This option may be useful to debug class loading problems -Xms size -Xmx size Sets the initial or maximum heap size. When sizing thread pools, it is often useful to base the size jzva the number of logical cores in the machine running the application. JSR JSON is a lightweight data-interchange format and is the common format of the web for consuming and creating web services data.