RELEASE NOTES FOR: 20 ==================================================================================================== Notes generated: Thu Dec 01 01:43:45 CET 2022 Hint: Prefix bug IDs with https://bugs.openjdk.org/browse/ to reach the relevant JIRA entry. JAVA ENHANCEMENT PROPOSALS (JEP): JEP 429: Scoped Values (Incubator) Introduce _scoped values_, which enable the sharing of immutable data within and across threads. They are preferred to thread-local variables, especially when using large numbers of virtual threads. This is an [incubating API](https://openjdk.org/jeps/11). JEP 432: Record Patterns (Second Preview) Enhance the Java programming language with _record patterns_ to deconstruct record values. Record patterns and type patterns can be nested to enable a powerful, declarative, and composable form of data navigation and processing. This is a [preview language feature](https://openjdk.org/jeps/12). JEP 433: Pattern Matching for switch (Fourth Preview) Enhance the Java programming language with pattern matching for `switch` expressions and statements. Extending pattern matching to `switch` allows an expression to be tested against a number of patterns, each with a specific action, so that complex data-oriented queries can be expressed concisely and safely. This is a [preview language feature](https://openjdk.org/jeps/12). JEP 434: Foreign Function & Memory API (Second Preview) Introduce an API by which Java programs can interoperate with code and data outside of the Java runtime. By efficiently invoking foreign functions (i.e., code outside the JVM), and by safely accessing foreign memory (i.e., memory not managed by the JVM), the API enables Java programs to call native libraries and process native data without the brittleness and danger of JNI. This is a [preview API](https://openjdk.org/jeps/12). JEP 436: Virtual Threads (Second Preview) Introduce *virtual threads* to the Java Platform. Virtual threads are lightweight threads that dramatically reduce the effort of writing, maintaining, and observing high-throughput concurrent applications. This is a [preview API](https://openjdk.java.net/jeps/12). JEP 437: Structured Concurrency (Second Incubator) Simplify multithreaded programming by introducing an API for *structured concurrency*. Structured concurrency treats multiple tasks running in different threads as a single unit of work, thereby streamlining error handling and cancellation, improving reliability, and enhancing observability. This is an [incubating API](https://openjdk.org/jeps/11). RELEASE NOTES: tools/javac: JDK-8244681: Javac Warns about Type Casts in Compound Assignments with Possible Lossy Conversions New lint option `lossy-conversions` has been added to `javac` to warn about type casts in compound assignments with possible lossy conversions. If the type of the right-hand operand of a compound assignment is not assignment compatible with the type of the variable, a cast is implied and possible lossy conversion may occur. The new warnings can be suppressed using `@SuppressWarnings("lossy-conversions")`. core-libs/java.net: JDK-8294241: java.net.URL constructors are deprecated The `java.net.URL` constructors are deprecated in this release. Developers are encouraged to use `java.net.URI` to parse or construct a URL. In cases where an instance of `java.net.URL` is needed to open a connection, `java.net.URI` can be used to construct or parse the URL string, possibly calling `URI::parseServerAuthority()` to validate that the authority component can be parsed as a server-based authority, and then calling `URI::toURL()` to create the `URL` instance. A new method, `URL::of(URI, URLStreamHandler)` is provided for the advanced usages where there is a need to construct a `URL` with a given custom stream handler. See the `java.net.URL` API documentation [1] for more details [2]. [1] https://download.java.net/java/early_access/jdk20/docs/api/java.base/java/net/URL.html#constructor-summary [2] https://download.java.net/java/early_access/jdk20/docs/api/java.base/java/net/URL.html#constructor-deprecation JDK-8297030: HttpClient Default Keep Alive Time is 30 Seconds In this release the default idle connection timeout value for the HTTP/1.1 and HTTP/2 connections created by the `java.net.http.HttpClient` has been reduced from 1200 seconds to 30 seconds. JDK-8293590: URL constructors called with malformed input may throw MalformedURLException for cases where it wasn't thrown previously The parsing of input provided to the `java.net.URL` constructors has changed in this release to be more strict. If the URL constructors are called with malformed input then `MalformedURLException` may be thrown for cases where it wasn’t thrown previously. In previous releases, some of the parsing/validation performed by the JDK built-in `URLStreamHander` implementations was delayed until `URL::openConnection` or `URLConnection::connect` was called. Some of these parsing/validation are now performed early, within URL constructors. An exception caused by a malformed URL that would have been delayed until the connection was opened or connected might now cause a `MalformedURLException` to be thrown at URL construction time. This change only affects URL instances that delegate to JDK built in stream handler implementations. Only applications relying on JDK built-in stream handlers should be affected. Applications relying on custom third party `URLStreamHandler` implementations should remain unaffected. A new JDK specific system property `-Djdk.net.url.delayParsing` or `-Djdk.net.url.delayParsing=true` can be specified on the command line to revert to the previous behavior. By default, the property is not set, and the new behavior is in place. The property can be specified on the java command line if unexpected regressions are observed. This new property is provided for backward compatibility and may be removed in a future release. hotspot/jvmti: JDK-8296472: appendToClassPathForInstrumentation must be used in a thread-safe manner When running an application with a Java agent (e.g. `-javaagent:myagent.jar`) and a custom system class loader (e.g. `-Djava.system.class.loader=MyClassLoader`), and the Java agent invokes the `Instrumentation.appendToSystemClassLoaderSearch` API to append to the class loader search, then the custom system class loader `appendToClassPathForInstrumentation` method will be invoked to add the JAR file to the custom system class loader's search path. The JVM no longer synchronizes on the custom class loader while calling `appendToClassPathForInstrumentation`. The `appendToClassPathForInstrumentation` method in the custom class loader must add to the class search path in a thread-safe manner. JDK-8218885: can_pop_frame and can_force_early_return Capabilities are Disabled if JVMCI Compiler is Used The JVMTI `can_pop_frame` and `can_force_early_return` capabilities are disabled if a JVMCI compiler (like Graal) is used. As a result the corresponding functionality (`PopFrame` and `ForceEarlyReturnXXX` functions) is not available to JVMTI agents. This issue is tracked by [JDK-8218885](https://bugs.openjdk.java.net/browse/JDK-8218885). JDK-8288387: GetLocalXXX/SetLocalXXX spec should require suspending target thread The JVM TI spec of the GetLocalXXX/SetLocalXXX functions has been changed to require the target thread to be either suspended or the current thread. The error code JVMTI_ERROR_THREAD_NOT_SUSPENDED will be returned if this requirement is not satisfied. The JVM TI agents which use the GetLocalXXX/SetLocalXXX API's need to be updated to suspend target thread if it is not the current thread. The full list of impacted JVM TI functions is: - GetLocalObject, GetLocalInt, GetLocalLong, GetLocalFloat, GetLocalDouble, GetLocalInstance, - SetLocalObject, SetLocalInt, SetLocalLong, SetLocalFloat, SetLocalDouble security-libs/javax.security: JDK-8297276: Remove thread text from Subject.current The specification of `Subject.current` has been changed in this release to drop the expectation that the `Subject` is inherited when creating a thread. At this time, the `Subject` is stored in the `AccessControlContext` and is inherited when creating platform threads. Virtual threads do not capture the caller context at thread creation time and the `AccessControlContext` is not inherited. Inheritance will be re-examined in a future release in advance of removing support for the `SecurityManager` and the inherited `AccessControlContext`. core-libs/java.util:i18n: JDK-8284840: Support for CLDR Version 42 Locale data based on Unicode Consortium's CLDR has been upgraded to version 42. For the detailed locale data changes, please refer to the Unicode Consortium's CLDR release notes: [https://cldr.unicode.org/index/downloads/cldr-42](https://cldr.unicode.org/index/downloads/cldr-42) Some of the notable changes in the upstream that may affect formatting are: - [" at " is no longer used for standard date/time format](https://unicode-org.atlassian.net/browse/CLDR-14032) - [NBSP prefixed to `a`, instead of a normal space](https://unicode-org.atlassian.net/browse/CLDR-14831) - [Fix first day of week info for China (CN)](https://unicode-org.atlassian.net/browse/CLDR-11510) - [Japanese: Support numbers up to 9999京](https://unicode-org.atlassian.net/browse/CLDR-15966) core-libs/java.lang: JDK-8249627: Thread.suspend/resume changed to throw UnsupportedOperationException The ability to suspend or resume a Thread with the `Thread.suspend()` and `Thread.resume()` methods has been removed in this release. The methods have been changed to throw `UnsupportedOperationException`. These methods were inherently deadlock prone and have been deprecated since JDK 1.2 (1998). The corresponding methods in `ThreadGroup`, to suspend or resume a group of threads, were changed to throw `UnsupportedOperationException` in Java 19. JDK-8289610: java.lang.ThreadGroup Is degraded Legacy `java.lang.ThreadGroup` has been degraded in this release. It is no longer possible to explicitly destroy a thread group. In its place, `ThreadGroup` is changed to no longer keep a strong reference to subgroups. A thread group is thus eligible to be GC'ed when there are no live threads in the group and nothing else is keeping the thread group alive. The behavior of several methods, deprecated for removal in prior releases, are changed as follows: - The `destroy` method does nothing. - The `isDestroyed` method returns false. - The `setDaemon` and `isDaemon` methods set/get a daemon status that is not used for anything. - The `suspend`, `resume`, and `stop` methods throw `UnsupportedOperationException`. For further details, see the [JEP 425, section java.lang.ThreadGroup](https://openjdk.java.net/jeps/425#java-lang-ThreadGroup). JDK-8289610: Thread.Stop changed to throw UnsupportedOperationException The ability to "stop" a Thread with the `Thread.stop()` method has been removed in this release. The method has been changed to throw `UnsupportedOperationException`. Stopping a Thread by causing it to throw `java.lang.ThreadDeath` was inherently unsafe. The `stop` method has been deprecated since JDK 1.2 (1998). The corresponding method in `ThreadGroup`, to "stop" a group of threads, was changed to throw `UnsupportedOperationException` in Java 19. As part of this change, `java.lang.ThreadDeath` has been deprecated, for removal. JDK-8284842: Support Unicode 15.0 This release upgrades Unicode support to 15.0, which includes the following: The `java.lang.Character` class supports the Unicode Character Database of 15.0 level, which adds 4,489 characters, for a total of 149,186 characters. These additions include 2 new scripts, for a total of 161 scripts, as well as 20 new emoji characters, and 4,193 CJK (Chinese, Japanese, and Korean) ideographs. The `java.text.Bidi` and `java.text.Normalizer` classes support 15.0 level of Unicode Standard Annexes, #9 and #15, respectively. The `java.util.regex` package supports Extended Grapheme Clusters based on the 15.0 level of Unicode Standard Annex #29 For more detail about Unicode 15.0, refer to the [Unicode Consortium's release note](https://unicode.org/versions/Unicode15.0.0/). hotspot/runtime: JDK-8295673: Deprecate and Disable Legacy Parallel Class Loading Workaround for Non-Parallel-Capable Class Loaders Some user-defined older class loaders would workaround a deadlock issue by releasing the class loader lock during the loading process. To prevent these loaders from encountering a “java.lang.LinkageError: attempted duplicate class definition” while loading the same class by parallel threads, the HotSpot Virtual Machine introduced a workaround in JDK 6 that serialized the load attempts, causing the subsequent attempts to wait for the first to complete. The need for class loaders to work this way was removed in JDK 7 when parallel-capable class loaders were introduced, but the workaround remained in the VM. That workaround is finally being removed and as a first step has been deprecated and disabled by default. If you start seeing "java.lang.LinkageError: attempted duplicate class definition" then you may have an affected legacy class loader. The flag `-XX:+EnableWaitForParallelLoad` can be used to temporarily restore the old behavior in this release of the JDK, but the legacy class loader will need to be updated for future releases. See the CSR request (JDK-8295848) for more background and details. core-libs/java.util:collections: JDK-8178355: IdentityHashMap's Remove and Replace Methods Use Object Identity The `remove(key, value)` and `replace(key, oldValue, newValue)` implementations of `IdentityHashMap` have been corrected. In previous releases, the value arguments were compared with values in the map using `equals`. However, `IdentityHashMap` specifies that all such comparisons should be made using object identity (`==`). These methods' implementations now conform to the specification. security-libs/java.security: JDK-8292177: New JFR Event: jdk.InitialSecurityProperty A new Java Flight Recorder (JFR) event has been added to record details of initial security properties when loaded via the `java.security.Security` class. The new event name is `jdk.InitialSecurityProperty` and contains the following fields: | Field name | Field Description | | ------------------------ | --------------------------- | |key | Security Property Key | |value | Corresponding Security Property Value | This new JFR event is enabled by default. The `java.security.debug=properties` system property will also now print initial security properties to standard error stream. With this new event and the already available 'jdk.SecurityPropertyModification' event (when enabled since it is not enabled by default), a JFR recording can now monitor the initial settings of all security properties and any subsequent changes. JDK-8296226: Added constructors (String, Throwable) and (Throwable) to InvalidParameterException Constructors `InvalidParameterException(String, Throwable)` and `InvalidParameterException(Throwable)` have been added to the `java.security.InvalidParameterException` class to support easy construction of `InvalidParameterException` objects with a cause. JDK-8155246: Throw Error if default java.security file fails to load A behavioral change has been made in the case where the default `conf/security/java.security` security configuration file fails to load. In such a scenario, the JDK will now throw an `InternalError`. Such a scenario should never occur. The default security file should always be present. Prior to this change, a static and outdated security configuration was loaded. JDK-8254711: New JFR Event: jdk.SecurityProviderService A new Java Flight Recorder (JFR) event has been added to record details of `java.security.Provider.getService(String type, String algorithm)` calls. The new event name is `jdk.SecurityProviderService` and contains the following fields: | Field name | Field Description | | ------------------------ | --------------------------- | |type | Type of Service | |algorithm |Algorithm Name | |provider | Security Provider | This event is disabled by default and can be enabled via the JFR configuration files or via standard JFR options. JDK-8282730: New Implementation Note for LoginModule on Removing Null from a Principals or Credentials set The `Set` implementation that holds principals and credentials in a JAAS `Subject` prohibits null elements and any attempt to add, query, or remove a null element will result in a `NullPointerException`. This is especially important when trying to remove principals or credentials from the subject at the logout phase but they are null because of a previous failed login. Various JDK `LoginModule` implementations have been fixed to avoid the exception. An Implementation Note has also been added to the `logout()` method of the `LoginModule` interface. Developers should verify and if necessary update any custom `LoginModule` implementations to be compliant with this implementation advice. core-libs/java.time: JDK-8292579: Update Timezone Data to 2022c This version includes changes from 2022b that merged multiple regions that have the same timestamp data post-1970 into a single time zone database. All time zone IDs remain the same but the merged time zones will point to a shared zone database. As a result, pre-1970 data may not be compatible with earlier JDK versions. The affected zones are ```Antarctica/Vostok, Asia/Brunei, Asia/Kuala_Lumpur, Atlantic/Reykjavik, Europe/Amsterdam, Europe/Copenhagen, Europe/Luxembourg, Europe/Monaco, Europe/Oslo, Europe/Stockholm, Indian/Christmas, Indian/Cocos, Indian/Kerguelen, Indian/Mahe, Indian/Reunion, Pacific/Chuuk, Pacific/Funafuti, Pacific/Majuro, Pacific/Pohnpei, Pacific/Wake, Pacific/Wallis, Arctic/Longyearbyen, Atlantic/Jan_Mayen, Iceland, Pacific/Ponape, Pacific/Truk, and Pacific/Yap```. For more details, refer to the announcement of [2022b](https://mm.icann.org/pipermail/tz-announce/2022-August/000071.html) core-libs/java.text: JDK-8291660: Grapheme support in BreakIterator Character boundary analysis in `java.text.BreakIterator` now conforms to Extended Grapheme Clusters breaks defined in Unicode Consortium's Standard Annex #29. This change will introduce intentional behavioral changes because the old implementation simply breaks at the code point boundaries for the vast majority of characters. For example, this is a String that contains the US flag and a grapheme for a 4-member-family. ``` "🇺🇸👨‍👩‍👧‍👦" ``` This String will be broken into two graphemes with the new implementation: ``` "🇺🇸", "👨‍👩‍👧‍👦" ``` whereas the old implementation simply breaks at the code point boundaries: ``` "🇺", "🇸", "👨", "(zwj)", "👩", "(zwj)", "👧", "(zwj)"‍, "👦" ``` where (zwj) denotes ZERO WIDTH JOINER (U+200D). core-libs/java.util.jar: JDK-8292327: InflaterInputStream.read Throws EOFException A change to `java.util.zip.InflaterInputStream` in this release means it is possible that reading uncompressed bytes with this API can fail with an unexpected `java.io.EOFException`. The issue arises when reading uncompressed bytes with a byte array that isn't large enough to fit all bytes that have been uncompressed. In that case, the additional uncompressed bytes are buffered by the implementation to be consumed by the next call to the `read` method. If the compressed stream is at end of stream then a subsequent `read` of the uncompressed data will fail incorrectly with `EOFException`. This issue will be fixed in a future update. It may be possible to workaround the issue in some cases by calling `read` with a larger bye array. security-libs/javax.net.ssl: JDK-8256660: Disabled DTLS 1.0 DTLS 1.0 has been disabled by default, by adding "DTLSv1.0" to the `jdk.tls.disabledAlgorithms` security property in the `java.security` configuration file. DTLS 1.0 has weakened over time and lacks support for stronger cipher suites. Any attempts to use DTLSv1.0 will fail with an `SSLHandshakeException`. Users can, at their own risk, re-enable the version by removing "DTLSv1.0" from the `jdk.tls.disabledAlgorithms` security property. JDK-8279164: Disabled TLS_ECDH_* Cipher Suites The TLS_ECDH_* cipher suites have been disabled by default, by adding "ECDH" to the `jdk.tls.disabledAlgorithms` security property in the `java.security` configuration file. The TLS_ECDH_* cipher suites do not preserve forward-secrecy and are rarely used in practice. Note that some TLS_ECDH_* cipher suites were already disabled because they use algorithms that are disabled, such as 3DES and RC4. This action disables the rest. Any attempts to use cipher suites starting with "TLS_ECDH_" will fail with an `SSLHandshakeException`. Users can, at their own risk, re-enable these cipher suites by removing "ECDH" from the `jdk.tls.disabledAlgorithms` security property. security-libs/javax.crypto: JDK-8247645: Provide ChaCha20 Intrinsics on x86_64 and aarch64 Platforms This feature delivers optimized intrinsic implementations for the ChaCha20 cipher supplied by the SunJCE provider. These optimized routines are designed for x86_64 chipsets that support the AVX, AVX2 and/or AVX512 instruction sets, and aarch64 chips supporting the Advanced SIMD instruction set. These intrinsics are enabled by default on supporting platforms, but may be disabled by providing the `-XX:-UseChaCha20Intrinsics` command-line option to Java. core-libs/java.nio: JDK-8057113: The new method Path::getExtension returns the file’s extension Support for obtaining the file extension of a file path's name is added via a new default method `java.nio.file.Path::getExtension`. Some examples: | File Name String | Extension | |------------------|-----------| | "foo.tar.gz" | "gz" | | "foo.bar" | "bar" | | "foo." | "" | | "foo" | `null` | | ".bar" | `null` | JDK-6924219: FileChannel positional write is unspecified in APPEND mode The specification of `java.nio.channels.FileChannel` is updated to clarify that the effect of attempting to write at a specific position using the `FileChannel::write(ByteBuffer,long)` method is system-dependent when the channel is open in append mode (`java.nio.file.StandardOpenOption.APPEND` is passed to `FileChannel::open` when the channel is opened). In particular, on some operating systems bytes will be written at the given position, while on other operating systems the given position will be ignored and the bytes will be appended to the file. JDK-8289689: Do not normalize file paths to Unicode Normalization Format D on macOS On macOS, file names are no longer normalized to Apple's variant of Unicode Normalization Format D. File names were normalized on HFS+ prior to macOS 10.13, but on APFS on macOS 10.13 and newer this normalization is no longer effected. The previous behavior may be enabled by setting the system property "jdk.nio.path.useNormalizationFormD" to "true". core-libs/java.math: JDK-8289260: Restore Behavior of java.math.BigDecimal.movePointLeft() and movePointRight() on a Zero Argument When these methods are invoked with a zero argument on a target with a negative _scale_, they return a result which is numerically the same as the target, but with a different _unscaled value_ and _scale_. In earlier releases, they returned a result with the same _unscaled value_ and _scale_, which was against the specification. The behavior is unchanged when the target has a non-negative _scale_ or when the argument is not zero. hotspot/gc: JDK-8292654: G1 Remembered set memory footprint regression after JDK-8286115 JDK-8286115 changed ergonomic sizing of a component of the remembered sets in G1. This change causes increased native memory usage of the Hotspot VM for applications that create large remembered sets with the G1 collector. In an internal benchmark total GC component native memory usage rose by almost 10% (from 1.2GB to 1.3GB). This issue can be worked around by passing double the value of `G1RemSetArrayOfCardsEntries` as printed by running the application with `-XX:+PrintFlagsFinal -XX:+UnlockExperimentalVMOptions` to your application. E.g. pass `-XX:+UnlockExperimentalVMOptions -XX:G1RemSetArrayOfCardsEntries=128` if a previous run showed a value of `64` for `G1RemSetArrayOfCardsEntries` in the output of `-XX:+PrintFlagsFinal`. This issue has been addressed in JDK 19.0.1 or later.