Shenandoah trades concurrent cpu cycles and space for pause time improvements. Shenandoah is an open-source low-pause time collector for OpenJDK designed to move us closer to those goals. In order to meet the lower end of that goal we need garbage collection algorithms which are efficient enough to allow programs to run in the available memory, but also optimized to never interrupt the running program for more than a handful of milliseconds. Service Level Agreement (SLA) applications guarantee response times of 10-500ms. Modern machines have more memory and more processors than ever before. This project will be a success if we can keep consistent short gc pause times. Pause times due to reasons other than GC like Time To Safe Point (TTSP) issues or monitor inflation are outside the scope of this JEP. The goal is not to fix all JVM pause issues. Shenandoah is an appropriate algorithm for applications which value responsiveness and predictable short pauses. There are other garbage collection algorithms which prioritize throughput or memory footprint over responsiveness. Pause times with Shenandoah are independent of heap size, meaning you will have the same consistent pause times whether your heap is 200 MB or 200 GB. Source: I work on OpenJDK Windows builds at RH.Add a new garbage collection (GC) algorithm named Shenandoah which reduces GC pause times by doing evacuation work concurrently with the running Java threads. RH OpenJDK 8 installer includes a WebStart implementation RH OpenJDK 8 installer includes a JavaFX implementation RH OpenJDK 8 includes a set of font filesĪll native binaries in RH OpenJDK 8 are signed by RH certificate RH OpenJDK 8 does not include demos and samples RH OpenJDK 8 includes all Java sources code inside the src.zip file (that is used by IDEs to allow browsing jdk code), in upstream build substantial part of these sources is not included RH OpenJDK 8 may use slightly newer timezone data - it is taken from RHEL/CentOS RH OpenJDK 8 uses the set of root CA certificates from RHEL/CentOS RH OpenJDK 8 uses sources from RHEL/CentOS for dependency libraries (zlib, giflib, libjpeg-turbo, libpng, nss ( nss is not used anymore)) instead of the (partial) sources of these libraries that are included in-tree in upstream jdk sourcesĮlliptic Crypto implementation in RH OpenJDK 8 includes only 3 most popular elliptic curves - NIST P-256, NIST P-384 and NIST P-521. RH OpenJDK 8 includes Shenandoah garbage collector RHEL/CentOS changes can be tracked in a publicly-available repo for CentOS RPM These sources are generally very close to upstream sources, but contain some changes (see points below) and may include some bugfixes (RPM patches) ahead of time. RH OpenJDK 8 build is done from the sources of OpenJDK RPM package that is used on RHEL/CentOS. Generally Red Hat builds are trying to stay as close as possible in behaviour to OpenJDK 8 package that is included in RHEL and CentOS. Technical differences between Red Hat OpenJDK 8 for Windows and other mentioned builds are pretty minor, as all these builds pass TCK. All the restrictions about the "development use" are related only to the subscription (support) that can be purchased from Red Hat. Red Hat provides OpenJDK 8 Windows binaries under exactly the same license as AdoptOpenJDK and any other open-source OpenJDK 8 build - under the GNU GPL v.
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