michalkurka [Wed, 17 Mar 2021 17:12:21 +0000 (13:12 -0400)]
Fix a race condition in CtClassType#getClassFile3
javassist fails to find a class when concurrently running process
compresses the class (converts classfile to raw bytes)
the idea of the fix is to make sure to only update rawClassfile and classfile
under lock in getClassFile3, all other places that modify classfile are
already synchronized
when reading the object state, we need to read under lock both classfile and
rawClassFile otherwise we might get an inconsistent state
modifies javassist.util.proxy.DefinePackageHelper to be compatible to Java 11.
It also adds a javadoc comment to CtClass#toClass() to recommend the users to use #toClass(Class) or #toClass(Lookup).
Andres Luuk [Mon, 9 Jul 2018 08:05:25 +0000 (11:05 +0300)]
Custom URL stream handler in ByteArrayClassPath
Otherwise a normal streamhandler lookup is made and if javassist is used early on server startup protses this can lead to a deadlock on rare cases on WebSpheare.
For example. A new StreamHandlerFactory is registered but not jet fully initialized. Now javassist is used at the same time but form another thread and it will be the first one to invoke the new StreamHandlerFactory and now it can deadlock with the other thread:
Snipets from my deadlock:
3XMTHREADINFO "main" J9VMThread:0x000000000175EC00, omrthread_t:0x00007F4120008100, java/lang/Thread:0x00000000624290B8, state:B, prio=5
3XMTHREADBLOCK Blocked on: org/osgi/util/tracker/ServiceTracker$Tracked@0x00000000627F0A90 Owned by: "other-thread" (J9VMThread:0x0000000001B26300, java/lang/Thread:0x00000000629F1458)
3XMHEAPALLOC Heap bytes allocated since last GC cycle=0 (0x0)
3XMTHREADINFO3 Java callstack:
4XESTACKTRACE at org/osgi/util/tracker/ServiceTracker.getServiceReferences(ServiceTracker.java:525)
4XESTACKTRACE at org/eclipse/osgi/framework/internal/protocol/StreamHandlerFactory.createInternalURLStreamHandler(StreamHandlerFactory.java:162)
4XESTACKTRACE at org/eclipse/osgi/framework/internal/protocol/StreamHandlerFactory.createURLStreamHandler(StreamHandlerFactory.java:118)
4XESTACKTRACE at java/net/URL.getURLStreamHandler(URL.java:1154)
4XESTACKTRACE at java/net/URL.<init>(URL.java:611(Compiled Code))
4XESTACKTRACE at java/net/URL.<init>(URL.java:502(Compiled Code))
4XESTACKTRACE at java/net/URL.<init>(URL.java:451)
4XESTACKTRACE at javassist/ByteArrayClassPath.find(JRebel:92)
...
4XESTACKTRACE at java/lang/ClassLoader.loadClassHelper(ClassLoader.java:924(Compiled Code))
5XESTACKTRACE (entered lock: org/eclipse/core/launcher/Main$StartupClassLoader@0x0000000062F3AA88, entry count: 1)
3XMTHREADINFO "other-thread" J9VMThread:0x0000000001B26300, omrthread_t:0x00007F4120A5D060, java/lang/Thread:0x00000000629F1458, state:B, prio=5
3XMTHREADBLOCK Blocked on: org/eclipse/core/launcher/Main$StartupClassLoader@0x0000000062F3AA88 Owned by: "main" (J9VMThread:0x000000000175EC00, java/lang/Thread:0x00000000624290B8)
3XMHEAPALLOC Heap bytes allocated since last GC cycle=0 (0x0)
3XMTHREADINFO3 Java callstack:
4XESTACKTRACE at org/osgi/util/tracker/AbstractTracked.size(AbstractTracked.java:356)
4XESTACKTRACE at org/osgi/util/tracker/ServiceTracker.getServiceReferences(ServiceTracker.java:526)
5XESTACKTRACE (entered lock: org/osgi/util/tracker/ServiceTracker$Tracked@0x00000000627F0A90, entry count: 1)
4XESTACKTRACE at org/eclipse/osgi/framework/internal/protocol/StreamHandlerFactory.createInternalURLStreamHandler(StreamHandlerFactory.java:162)
4XESTACKTRACE at org/eclipse/osgi/framework/internal/protocol/StreamHandlerFactory.createURLStreamHandler(StreamHandlerFactory.java:118)
4XESTACKTRACE at java/net/URL.getURLStreamHandler(URL.java:1154)
4XESTACKTRACE at java/net/URL.<init>(URL.java:611(Compiled Code))
4XESTACKTRACE at java/net/URL.<init>(URL.java:502(Compiled Code))
4XESTACKTRACE at java/net/URL.<init>(URL.java:451)
4XESTACKTRACE at java/net/URI.toURL(URI.java:1100)
4XESTACKTRACE at com/ibm/jsse2/av.a(av.java:92)
4XESTACKTRACE at com/ibm/jsse2/av.engineInit(av.java:7)
4XESTACKTRACE at javax/net/ssl/TrustManagerFactory.init(TrustManagerFactory.java:25)