Chapter 2. Eclipse Temurin features

Eclipse Temurin does not contain structural changes from the upstream distribution of OpenJDK.

For the list of changes and security fixes included in the latest OpenJDK 17 release of Eclipse Temurin, see OpenJDK 17.0.5 Released.

New features and enhancements

Review the following release notes to understand new features and feature enhancements included with the Eclipse Temurin 17.0.5 release:

Disabled cpu.shares parameter

Before the OpenJDK 17.0.5 release, OpenJDK used an incorrect interpretation of the cpu.shares parameter, which belongs to Linux control groups, also known as cgroups. The parameter might cause a Java Virtual machine (JVM) to use fewer CPUs than available, which can impact the JVM’s CPU resources and performance when it operates inside a container.

The OpenJDK 17.0.5 release configures a JVM to no longer use the cpu.shares parameter when determining the number of threads for a thread pool. If you want to revert this configuration, pass the -XX:+UseContainerCpuShares argument on JVM startup.

See JDK-8281181 (JDK Bug System).

SHA-1 Signed JARs

With the OpenJDK 17.0.5 release, JARs signed with SHA-1 algorithms are restricted by default and treated as if they were unsigned. These restrictions apply to the following algorithms:

Additionally, the restrictions apply to signed Java Cryptography Extension (JCE) providers.

To reduce the compatibility risk for JARs that have been previously timestamped, the restriction does not apply to any JAR signed with SHA-1 algorithms and timestamped prior to January 01, 2019. This exception might be removed in a future OpenJDK release.

To determine if your JAR file is impacted by the restriction, you can issue the following command in your CLI:

$ jarsigner -verify -verbose -certs

From the output of the previous command, search for instance of SHA1 , SHA-1, or disabled. Additionally, search for any warning messages that indicate that the JAR will be treated as unsigned. For example:

Signed by "CN="Signer""
Digest algorithm: SHA-1 (disabled)
Signature algorithm: SHA1withRSA (disabled), 2048-bit key

WARNING: The jar will be treated as unsigned, because it is signed with a weak algorithm that is now disabled by the security property:

jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024, DSA keySize < 1024, SHA1 denyAfter 2019-01-01

Consider replacing or re-signing any JARs affected by the new restrictions with stronger algorithms.

If your JAR file is impacted by this restriction, you can remove the algorithm and re-sign the file with a stronger algorithm, such as SHA-256. If you want to remove the restriction on SHA-1 signed JARs for OpenJDK 17.0.5, and you accept the security risks, you can complete the following actions:

See JDK-8269039 (JDK Bug System).

SunMSCAPI provider supports new Microsoft Windows keystore types

The SunMSCAPI provider supports the following Microsoft Windows keystore types where you must append your local namespace to Windows-:

By specifying any of these types, you can provide access to your local computer’s location for the Microsoft Windows keystore. Thereby providing the keystore access to certificates that are stored on your local system.

See JDK-6782021 (JDK Bug System).

System properties for controlling the keep-alive behavior of HTTPURLConnection

The OpenJDK 17.0.5 release includes the following new system properties that you can use to control the keep-alive behavior of HTTPURLConnection:

Before the OpenJDK 17.0.5 release, a server or a proxy with an unspecified keep-alive time might cause an idle connection to remain open for a period defined by a hard-coded default value.

With OpenJDK 17.0.5, you can use system properties to change the default value for the keep-alive time. The keep-alive properties control this behavior by changing the HTTP keep-alive time of either a server or proxy, so that OpenJDK’s HTTP protocol handler closes idle connections after a specified number of seconds.

Before the OpenJDK 17.0.5 release, the following use cases would lead to specific keep-alive behaviors for HTTPURLConnection:

The OpenJDK 17.0.5 release maintains the previously described behavior, but you can now specify the timeouts in the second and third listed use cases by using the http.keepAlive.time.server and http.keepAlive.time.proxy properties, rather than having to rely on the default settings.

See JDK-8278067 (JDK Bug System).

Revised on 2024-05-03 15:35:32 UTC