Question

当我将Java从8升级到11时，我收到了Netty关于"jdk.internal.misc.Unsafe"的错误消息，详细信息如下：

我知道这是一条调试级别消息，我可以更改日志级别以忽略它。但是我不确定是否会忽略其他问题，例如性能。有谁知道最好的解决方案？

java.lang.IllegalAccessException: class io.netty.util.internal.PlatformDependent0$6 cannot access class jdk.internal.misc.Unsafe (in module java.base) because module java.base does not export jdk.internal.misc to unnamed module @84b8f0f
    at jdk.internal.reflect.Reflection.newIllegalAccessException(Reflection.java:361) ~[?:?]
    at java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:591) ~[?:?]
    at java.lang.reflect.Method.invoke(Method.java:558) ~[?:?]
    at io.netty.util.internal.PlatformDependent0$6.run(PlatformDependent0.java:334) ~[netty-all-4.1.36.Final.jar:4.1.36.Final]
    at java.security.AccessController.doPrivileged(Native Method) ~[?:?]
    at io.netty.util.internal.PlatformDependent0.<clinit>(PlatformDependent0.java:325) ~[netty-all-4.1.36.Final.jar:4.1.36.Final]
    at io.netty.util.internal.PlatformDependent.isAndroid(PlatformDependent.java:214) ~[netty-all-4.1.36.Final.jar:4.1.36.Final]
    at io.netty.util.internal.PlatformDependent.<clinit>(PlatformDependent.java:82) ~[netty-all-4.1.36.Final.jar:4.1.36.Final]
    at io.netty.buffer.UnpooledByteBufAllocator.<clinit>(UnpooledByteBufAllocator.java:37) ~[netty-all-4.1.36.Final.jar:4.1.36.Final]
    at io.netty.buffer.Unpooled.<clinit>(Unpooled.java:73) ~[netty-all-4.1.36.Final.jar:4.1.36.Final]
    at wedo.stream3.framework.base.connector.supplier.DelimiterDecoderSupplier.getDelimiter(DelimiterDecoderSupplier.java:41) ~[classes/:?]
    at wedo.stream3.framework.base.connector.supplier.DelimiterDecoderSupplier.<init>(DelimiterDecoderSupplier.java:26) ~[classes/:?]
    at wedo.stream3.framework.base.connector.supplier.DelimiterDecoderSupplier.<init>(DelimiterDecoderSupplier.java:20) ~[classes/:?]
    at wedo.stream3.framework.base.connector.supplier.CommonChannelHandlerSupplier.<init>(CommonChannelHandlerSupplier.java:37) ~[classes/:?]
    at wedo.stream3.framework.base.connector.supplier.CommonChannelHandlerSupplier.<init>(CommonChannelHandlerSupplier.java:25) ~[classes/:?]
    at wedo.stream3.framework.base.connector.TcpClientConnector.start(TcpClientConnector.java:39) ~[classes/:?]
    at wedo.stream3.framework.bootstrap.FrameworkLauncher.lambda$start$0(FrameworkLauncher.java:61) ~[classes/:?]
    at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) [?:?]
    at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177) [?:?]
    at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1654) [?:?]
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) [?:?]
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) [?:?]
    at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) [?:?]
    at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) [?:?]
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) [?:?]
    at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497) [?:?]
    at wedo.stream3.framework.bootstrap.FrameworkLauncher.start(FrameworkLauncher.java:58) [classes/:?]
    at org.stream3.prototype.mfc.App.launchFramework(App.java:58) [classes/:?]
    at org.stream3.prototype.mfc.App.main(App.java:41) [classes/:?]

Answer 1

要允许netty访问该类，请使用以下选项启动java：

--add-opens java.base/jdk.internal.misc=ALL-UNNAMED

这会将模块jdk.internal.misc中的软件包java.base打开到未修改的模块。

另请参阅java command和此intro to the Java module system的文档。

编辑：要让Netty使用其直接缓冲区优化，还需要设置

-Dio.netty.tryReflectionSetAccessible=true

与此主题相关的许多Netty问题，请参见例如netty/issues/7769

Answer 2

在Java 11下运行Netty时，请使用以下VM选项：

--add-opens java.base/jdk.internal.misc=ALL-UNNAMED
-Dio.netty.tryReflectionSetAccessible=true

然后，要知道何时使用深反射，请添加：

--illegal-access=warn

Answer 3

正如您所说，这只是一条调试消息，可以忽略。它基本上告诉您Netty无法使用“所有优化”，因为它无法访问类。如果需要，可以在启动应用程序时通过命令行标志打开访问级别。

Netty-无法访问类jdk.internal.misc.Unsafe

3 个答案: