Fix JRuby embed crash after application reloading #4312
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We use JRuby `ScriptingContainer` in a tomcat servlet web application. After application reloading in tomcat, JRuby runtime initialization fails with the error message. "BUG: could not initialize constructor handle" `MethodHandles.publicLookup().findConstructor()` fails with `IllegalAccessException` in static initialization block. The initialization does not work well with tomcat reloading. As a workaround `MethodHandles.lookup()` without access check works fine.
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Here is a test code for the issue. With jruby-complete-9.1.6.0.jar, this fails with the following Exception. import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
public class TestReload {
public static void main(String[] args) {
try {
for (int i = 0; i < 2; i++) {
// load class
URLClassLoader loader = new URLClassLoader(new URL[] {
new URL("jar:file:./jruby-complete.jar!/")
});
Class<?> container = loader.loadClass("org.jruby.embed.ScriptingContainer");
Method runScriptlet = container.getMethod("runScriptlet", String.class);
Method setClassLoader = container.getMethod("setClassLoader", ClassLoader.class);
Object c = container.newInstance();
setClassLoader.invoke(c, loader);
runScriptlet.invoke(c, "puts \"Hello World!\"");
// unload class
loader = null;
c = null;
System.gc();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}$ java TestReload
Hello World!
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at TestReload.main(TestReload.java:18)
Caused by: java.lang.ExceptionInInitializerError
at org.jruby.runtime.ThreadContext.<init>(ThreadContext.java:201)
at org.jruby.runtime.ThreadContext.newContext(ThreadContext.java:76)
at org.jruby.internal.runtime.ThreadService.initMainThread(ThreadService.java:166)
at org.jruby.Ruby.init(Ruby.java:1238)
at org.jruby.Ruby.newInstance(Ruby.java:339)
at org.jruby.embed.internal.AbstractLocalContextProvider.getGlobalRuntime(AbstractLocalContextProvider.java:82)
at org.jruby.embed.internal.SingletonLocalContextProvider.getRuntime(SingletonLocalContextProvider.java:99)
at org.jruby.embed.internal.EmbedRubyRuntimeAdapterImpl.runParser(EmbedRubyRuntimeAdapterImpl.java:167)
at org.jruby.embed.internal.EmbedRubyRuntimeAdapterImpl.parse(EmbedRubyRuntimeAdapterImpl.java:94)
at org.jruby.embed.ScriptingContainer.parse(ScriptingContainer.java:1239)
at org.jruby.embed.ScriptingContainer.runScriptlet(ScriptingContainer.java:1299)
... 5 more
Caused by: java.lang.RuntimeException: BUG: could not initialize constructor handle
at org.jruby.runtime.scope.ManyVarsDynamicScope.<clinit>(ManyVarsDynamicScope.java:39)
... 16 more |
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Threads would be needed to unload loaded classes. import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
public class TestReload {
public static void main(String[] args) {
while (true) {
Thread t = new Thread() {
public void run() {
try (URLClassLoader loader = new URLClassLoader(new URL[] {
new URL("jar:file:./jruby-complete.jar!/")
})) {
// load class
Class<?> container = loader.loadClass("org.jruby.embed.ScriptingContainer");
Method runScriptlet = container.getMethod("runScriptlet", String.class);
Method setClassLoader = container.getMethod("setClassLoader", ClassLoader.class);
Method terminate = container.getMethod("terminate");
Object c = container.newInstance();
setClassLoader.invoke(c, loader);
runScriptlet.invoke(c, "puts \"Hello World!\"");
terminate.invoke(c);
} catch (Exception e) {
e.printStackTrace();
}
// unload class
System.gc();
System.runFinalization();
System.gc();
}
};
t.start();
try {
t.join();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}$ java -XX:+TraceClassUnloading TestReload
(snip)
[thread 9492 also had an error]
#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x000000006e4c24b0, pid=11608, tid=0x00000000000031e4
#
# JRE version: Java(TM) SE Runtime Environment (8.0_111-b14) (build 1.8.0_111-b14)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.111-b14 mixed mode windows-amd64 compressed oops)
# Problematic frame:
# C 0x000000006e4c24b0
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
#
# An error report file with more information is saved as:
(snip)hs_err_pid11608.log contains: |
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Nice investigation on this one. I'll try out your reproduction code and see if I can figure out what's going wrong. |
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Reproduced! Investigating. |
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Using MethodHandles.lookup() does indeed solve the issue, and I think it's a good change. The jnr-ffi crash is a separate issue and I'll investigate that. |
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We use JRuby
ScriptingContainerin a tomcat servlet webapplication. After application reloading in tomcat, JRuby
runtime initialization fails with the error message.
"BUG: could not initialize constructor handle"
MethodHandles.publicLookup().findConstructor()fails withIllegalAccessExceptionin static initialization block.The initialization does not work well with tomcat reloading.
As a workaround
MethodHandles.lookup()without access checkworks fine.