Attempt to reload the library in case of UnsatisfiedLinkError

[JasonFengJ9]

Attempt to reload the library in case of UnsatisfiedLinkError

When an UnsatisfiedLinkError is thrown because the library was already loaded in another classloader, run gc() to unload the unreachable classloaders, and reload the library again.

Java 8/11 UnsatisfiedLinkError message already loaded in another classloader is from

openj9/runtime/vm/vmbootlib.c

Lines 518 to 519 in 0027b81

	/* loading a library in multiple class loaders is not permitted */
	reportError(errBuf, "Library is already loaded in another ClassLoader", bufLen);

Java 17+ is from https://github.com/ibmruntimes/openj9-openjdk-jdk17/blob/4a311794a42998359c859814c645398be928e19a/src/java.base/share/classes/jdk/internal/loader/NativeLibraries.java#L206-L209

            // cannot be loaded by other class loaders
            if (loadedLibraryNames.contains(name)) {
                throw new UnsatisfiedLinkError("Native Library " + name +
                        " already loaded in another classloader");
            }

closes #19978

Signed-off-by: Jason Feng [email protected]

[pshipton]

jenkins test sanity amac jdk11,jdk17

[pshipton]

java/lang/Runtime/loadLibrary/LoadLibraryTest.java

16:49:16  STDOUT:
16:49:16  findLibrary someLibrary
16:49:16  Thread1 load
16:49:16  findLibrary awt
16:49:16  Thread2 load
16:49:16  STDERR:
16:49:16  java.lang.ExceptionInInitializerError
16:49:16  	at java.base/java.lang.J9VMInternals.ensureError(J9VMInternals.java:206)
16:49:16  	at java.base/java.lang.J9VMInternals.recordInitializationFailure(J9VMInternals.java:195)
16:49:16  	at java.base/java.lang.Class.forNameImpl(Native Method)
16:49:16  	at java.base/java.lang.Class.forName(Class.java:418)
16:49:16  	at LoadLibraryTest$2.run(LoadLibraryTest.java:137)
16:49:16  Caused by: java.lang.RuntimeException: someLibrary was loaded
16:49:16  	at Target.<clinit>(Target.java:28)
16:49:16  	... 3 more

[JasonFengJ9]

java/lang/Runtime/loadLibrary/LoadLibraryTest.java

Looking into it.

[pshipton]

J9vmTest

17:05:25  Able to open BigInteger library in different classLoader
17:05:25  Exception in thread "main" java.lang.RuntimeException
17:05:25  	at j9vm.test.libraryhandle.MultipleLibraryLoadTest.main(MultipleLibraryLoadTest.java:58)
17:05:25  non-zero exit value: 1
17:05:25  *** Test FAILED *** (j9vm.test.libraryhandle.MultipleLibraryLoadTest)

[pshipton]

jdk17 java/lang/ClassLoader/nativeLibrary/NativeLibraryTest.java

16:48:23  STDOUT:
16:48:23  count: 1
16:48:23  STDERR:
16:48:23  JVMJNCK001I JNI check utility installed. Use -Xcheck:jni:help for usage
16:48:23  java.lang.RuntimeException: should fail to load the native library by another class loader
16:48:23  	at NativeLibraryTest.runTest(NativeLibraryTest.java:97)
16:48:23  	at NativeLibraryTest.main(NativeLibraryTest.java:65)
16:48:23  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
16:48:23  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
16:48:23  	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
16:48:23  	at java.base/java.lang.reflect.Method.invoke(Method.java:575)
16:48:23  	at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
16:48:23  	at java.base/java.lang.Thread.run(Thread.java:857)

[pshipton]

Ah, if there is an UnsatisfiedLinkError, and it doesn't match the condition, the original UnsatisfiedLinkError needs to be re-thrown.

[JasonFengJ9]

Re-throwing the UnsatisfiedLinkError still failed java/lang/ClassLoader/nativeLibrary/NativeLibraryTest.java.

23:24:00  java.lang.RuntimeException: should fail to load the native library by another class loader
23:24:00  	at NativeLibraryTest.runTest(NativeLibraryTest.java:97)
23:24:00  	at NativeLibraryTest.main(NativeLibraryTest.java:65)
23:24:00  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
23:24:00  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
23:24:00  	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
23:24:00  	at java.base/java.lang.reflect.Method.invoke(Method.java:575)
23:24:00  	at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
23:24:00  	at java.base/java.lang.Thread.run(Thread.java:857)

The test depends on GC behaviour.
https://github.com/ibmruntimes/openj9-openjdk-jdk17/blob/94ec587a8a2c3e278d3bba093b980ad9ea343e22/test/jdk/java/lang/ClassLoader/nativeLibrary/NativeLibraryTest.java#L97-L98

        Runnable r = newTestRunnable();
        r.run();
        // reload the native library by the same class loader
        r.run();
        // load the native library by another class loader
        Runnable r1 = newTestRunnable();
        try {
            r1.run();
            throw new RuntimeException("should fail to load the native library" +
                    " by another class loader");
        } catch (UnsatisfiedLinkError e) {}

The test need to be modified or excluded after this PR.

[JasonFengJ9]

Opened an extension PR to modify the test

• keep Runnable r strongly reachable so that it is not reclaimable by GC ibmruntimes/openj9-openjdk-jdk#851

[pshipton]

jenkins compile amac jdknext

[JasonFengJ9]

The test changes have been merged in extension repos.

[pshipton]

jenkins test sanity amac jdk11,jdk17