RFR: 8339480: Build static-jdk image with a statically linked launcher [v8]

Jiangli Zhou jiangli at openjdk.org
Sun Nov 3 05:08:34 UTC 2024 

On Sat, 2 Nov 2024 01:05:27 GMT, Jiangli Zhou <jiangli at openjdk.org> wrote:

> > > I finally noticed that you are testing a precompiled HelloWorld class, and I have been running with a source file argument to have java compile it on the fly.
> > > When I try using a pre-compiled HelloWorld, the linux port works for me too.
> > > @jianglizhou Can you please verify if you can run this with a .java file directly? To be clear: this works fine on my mac with this PR, and (as I said), I'm pretty certain it used to work at least at some point during development on this PR.
> > > ```
> > > ihse at sthihse:/localhome/git/jdk-ALT$ cat > HelloWorld.java
> > > public class HelloWorld {
> > >   public static void main(String[] args) {
> > >     System.out.println("Hello, world!");
> > >   }
> > > }
> > > ihse at sthihse:/localhome/git/jdk-ALT$ javac HelloWorld.java 
> > > ihse at sthihse:/localhome/git/jdk-ALT$ ./build/linux-x64/images/static-jdk/bin/java HelloWorld 
> > > Hello, world!
> > > ihse at sthihse:/localhome/git/jdk-ALT$ ./build/linux-x64/images/static-jdk/bin/java HelloWorld.java
> > > Error: Unable to load main class com.sun.tools.javac.launcher.SourceLauncher in module jdk.compiler
> > > Caused by: java.lang.UnsatisfiedLinkError: no jimage in system library path: /localhome/git/jdk-ALT/build/linux-x64/images/static-jdk/bin
> > > Runtime.exit(1) logging failed: Could not initialize class jdk.internal.module.SystemModuleFinders$SystemImage
> > > ihse at sthihse:/localhome/git/jdk-ALT$ 
> > > ```
> > 
> > 
> > I can reproduce the issue with running a `.java` directly using static-jdk/bin/java built from your branch. The issue does not exist with the `bin/javastatic` built from https://github.com/openjdk/leyden/tree/hermetic-java-runtime (I just tested). I have a hunch of where is problem might be. I'll do some debugging.
> > ```
> > $ bin/java /usr/local/google/home/jianglizhou/tests/HelloWorld.java
> > Error: Unable to load main class com.sun.tools.javac.launcher.SourceLauncher in module jdk.compiler
> > Caused by: java.lang.UnsatisfiedLinkError: no jimage in system library path: /usr/local/google/home/jianglizhou/github/jdk_pull_20837/build/linux-x86_64-server-slowdebug/images/static-jdk/bin
> > Runtime.exit(1) logging failed: Could not initialize class jdk.internal.module.SystemModuleFinders$SystemImage
> > ```
> 
> Ok, I've found the cause. It's because `<jdk_build_path>/static-jdk/bin` instead of `<jdk_build_path>/static-jdk/lib` is set as the `_sun_boot_library_path` by `Arguments::set_dll_dir()`, during `os::init_system_properties_values()`. The path is retrieved via `StaticProperty.sunBootLibraryPath()` and used by `ClassLoader.loadLibrary()` to locate `jimage`. Hence the failure.
> 
> Looking at why it only fails with running with `.java` but not with `.class`, a quick looks shows me that the following call path is only taken when running with `.java`:
> 
> ```
> 	at java.base/java.lang.ClassLoader.loadLibrary(ClassLoader.java:2410)
> 	at java.base/java.lang.Runtime.loadLibrary0(Runtime.java:927)
> 	at java.base/java.lang.System.loadLibrary(System.java:2078)
> 	at java.base/jdk.internal.jimage.NativeImageBuffer$1.run(NativeImageBuffer.java:43)
> 	at java.base/jdk.internal.jimage.NativeImageBuffer$1.run(NativeImageBuffer.java:40)
> 	at java.base/java.security.AccessController.doPrivileged(AccessController.java:319)
> 	at java.base/jdk.internal.jimage.NativeImageBuffer.<clinit>(NativeImageBuffer.java:39)
> 	at java.base/jdk.internal.jimage.BasicImageReader.<init>(BasicImageReader.java:97)
> 	at java.base/jdk.internal.jimage.ImageReader$SharedImageReader.<init>(ImageReader.java:229)
> 	at java.base/jdk.internal.jimage.ImageReader$SharedImageReader.open(ImageReader.java:243)
> 	at java.base/jdk.internal.jimage.ImageReader.open(ImageReader.java:67)
> 	at java.base/jdk.internal.jimage.ImageReader.open(ImageReader.java:71)
> 	at java.base/jdk.internal.jimage.ImageReaderFactory$1.apply(ImageReaderFactory.java:70)
> 	at java.base/jdk.internal.jimage.ImageReaderFactory$1.apply(ImageReaderFactory.java:67)
> 	at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1714)
> 	at java.base/jdk.internal.jimage.ImageReaderFactory.get(ImageReaderFactory.java:61)
> 	at java.base/jdk.internal.jimage.ImageReaderFactory.getImageReader(ImageReaderFactory.java:85)
> 	at java.base/jdk.internal.module.SystemModuleFinders$SystemImage.<clinit>(SystemModuleFinders.java:385)
> 	at java.base/jdk.internal.module.SystemModuleFinders$SystemModuleReader.findImageLocation(SystemModuleFinders.java:429)
> 	at java.base/jdk.internal.module.SystemModuleFinders$SystemModuleReader.read(SystemModuleFinders.java:483)
> 	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:809)
> 	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassInModuleOrNull(BuiltinClassLoader.java:741)
> 	at java.base/jdk.internal.loader.BuiltinClassLoader.findClass(BuiltinClassLoader.java:621)
> 	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:640)
> 	at java.base/java.lang.Class.forName(Class.java:673)
> 	at java.base/java.lang.Class.forName(Class.java:648)
> 	at java.base/sun.launcher.LauncherHelper.loadModuleMainClass(LauncherHelper.java:798)
> 	at java.base/sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:733)
> ```
> 
> I'm going to look into a fix and update in this comment thread.
> 
> While investigating, I also just found there a new issue in https://github.com/openjdk/leyden/tree/hermetic-java-runtime. Let's focus on resolving the `.java` run issue with your PR to make progress first.

With further debugging I found the problem is actually due to failing to load `jimage` as a **built-in** native library. And, that's because `DEF_STATIC_JNI_OnLoad` is missing from jimage.cpp, see change in
https://github.com/openjdk/leyden/blob/3cfd92bfcc6e54377fc2cd4004c926db6aa5e16e/src/java.base/share/native/libjimage/jimage.cpp#L44. I'm going to create a bug to fix the missing `DEF_STATIC_JNI_OnLoad` in the mainline now.

With your PR, `libjimage.so` is statically linked into `static-jdk/bin/java`. As a result there is no `lib/libjimage.so`. So the `_sun_boot_library_path` issue that I pointed out earlier is not the direct cause of the failure. I don't think we need to address that in your PR. We can fix it later. I think we would need to decide what is the `dll_dir` with the static JDK support and hermetic support.

While debugging the issue, I found debugging symbols do not work for `static-jdk/bin/java`. There is no `static-jdk/bin/java.debuginfo`. I do see there's a `./support/static-native/launcher/java.debuginfo`. Please fix the debugging symbol issue in your PR.


Reading symbols from images/static-jdk/bin/java...
(No debugging symbols found in images/static-jdk/bin/java)
(gdb)

-------------

PR Comment: https://git.openjdk.org/jdk/pull/20837#issuecomment-2453298940

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