#194 Deadlock in gate application

[Yan]

Hi,

I've found deadlock when run duplicated CorpusController in several threads.
The reason is that in class gate.creole.AbstractResource
access to static field beanInfoCache is not synchronized.

Here is threads dump for deadlock:

Found one Java-level deadlock:

"IndexingThread-4[57]":
waiting to lock monitor 0x0000000002aa5198 (object 0x000000077bfc21f8, a gate.util.GateClassLoader),
which is held by "IndexingThread-2[55]"
"IndexingThread-2[55]":
waiting to lock monitor 0x0000000002aa6168 (object 0x000000077c086df0, a gate.util.GateClassLoader),
which is held by "IndexingThread-1[54]"
"IndexingThread-1[54]":
waiting to lock monitor 0x0000000002aa5198 (object 0x000000077bfc21f8, a gate.util.GateClassLoader),
which is held by "IndexingThread-2[55]"

Java stack information for the threads listed above:

"IndexingThread-4[57]":
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:270)
at com.sun.beans.finder.ClassFinder.findClass(ClassFinder.java:103)
at com.sun.beans.finder.InstanceFinder.instantiate(InstanceFinder.java:93)
at com.sun.beans.finder.InstanceFinder.find(InstanceFinder.java:66)
at java.beans.Introspector.findExplicitBeanInfo(Introspector.java:438)
at java.beans.Introspector.<init>(Introspector.java:388)
at java.beans.Introspector.getBeanInfo(Introspector.java:252)
at java.beans.Introspector.getBeanInfo(Introspector.java:214)
at gate.creole.AbstractResource.getBeanInfo(AbstractResource.java:493)
at gate.creole.AbstractResource.removeResourceListeners(AbstractResource.java:333)
at gate.creole.ConditionalSerialController.runComponent(ConditionalSerialController.java:182)
at gate.creole.SerialController.executeImpl(SerialController.java:157)
at gate.creole.ConditionalSerialAnalyserController.executeImpl(ConditionalSerialAnalyserController.java:244)
at gate.creole.ConditionalSerialAnalyserController.execute(ConditionalSerialAnalyserController.java:139)
at org.apache.nutch.data2life.index.MimirIndexWriter$IndexingThread.run(MimirIndexWriter.java:251)
"IndexingThread-2[55]":
at java.lang.ClassLoader.loadClass(ClassLoader.java:404)
- waiting to lock <0x000000077c086df0> (a gate.util.GateClassLoader)
at gate.util.GateClassLoader.loadClass(GateClassLoader.java:199)
at gate.util.GateClassLoader.loadClass(GateClassLoader.java:239)
at gate.util.GateClassLoader.loadClass(GateClassLoader.java:216)
at gate.util.GateClassLoader.loadClass(GateClassLoader.java:139)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:270)
at com.sun.beans.finder.ClassFinder.findClass(ClassFinder.java:103)
at com.sun.beans.finder.InstanceFinder.instantiate(InstanceFinder.java:93)
at com.sun.beans.finder.InstanceFinder.find(InstanceFinder.java:66)
at java.beans.Introspector.findExplicitBeanInfo(Introspector.java:438)
at java.beans.Introspector.<init>(Introspector.java:388)
at java.beans.Introspector.getBeanInfo(Introspector.java:252)
at java.beans.Introspector.getBeanInfo(Introspector.java:214)
at gate.creole.AbstractResource.getBeanInfo(AbstractResource.java:493)
at gate.creole.AbstractResource.removeResourceListeners(AbstractResource.java:333)
at gate.creole.ConditionalSerialController.runComponent(ConditionalSerialController.java:182)
at gate.creole.SerialController.executeImpl(SerialController.java:157)
at gate.creole.ConditionalSerialAnalyserController.executeImpl(ConditionalSerialAnalyserController.java:244)
at gate.creole.ConditionalSerialAnalyserController.execute(ConditionalSerialAnalyserController.java:139)
at org.apache.nutch.data2life.index.MimirIndexWriter$IndexingThread.run(MimirIndexWriter.java:251)
"IndexingThread-1[54]":
at java.lang.ClassLoader.loadClass(ClassLoader.java:404)
- waiting to lock <0x000000077bfc21f8> (a gate.util.GateClassLoader)
at gate.util.GateClassLoader.loadClass(GateClassLoader.java:199)
at gate.util.GateClassLoader.loadClass(GateClassLoader.java:239)
at gate.util.GateClassLoader.loadClass(GateClassLoader.java:216)
at gate.util.GateClassLoader.loadClass(GateClassLoader.java:139)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:270)
at com.sun.beans.finder.ClassFinder.findClass(ClassFinder.java:103)
at com.sun.beans.finder.InstanceFinder.instantiate(InstanceFinder.java:93)
at com.sun.beans.finder.InstanceFinder.find(InstanceFinder.java:66)
at java.beans.Introspector.findExplicitBeanInfo(Introspector.java:438)
at java.beans.Introspector.<init>(Introspector.java:388)
at java.beans.Introspector.getBeanInfo(Introspector.java:252)
at java.beans.Introspector.getBeanInfo(Introspector.java:214)
at gate.creole.AbstractResource.getBeanInfo(AbstractResource.java:493)
at gate.creole.AbstractResource.setResourceListeners(AbstractResource.java:295)
at gate.creole.ConditionalSerialController.runComponent(ConditionalSerialController.java:149)
at gate.creole.SerialController.executeImpl(SerialController.java:157)
at gate.creole.ConditionalSerialAnalyserController.executeImpl(ConditionalSerialAnalyserController.java:244)
at gate.creole.ConditionalSerialAnalyserController.execute(ConditionalSerialAnalyserController.java:139)
at org.apache.nutch.data2life.index.MimirIndexWriter$IndexingThread.run(MimirIndexWriter.java:251)

Found 1 deadlock.

[Jan Dedek]

I can confirm the bug. See my post at gate users:
https://sourceforge.net/p/gate/mailman/message/34109423/

It seems that making the method gate.creole.AbstractResource.getBeanInfo(Class<? extends Resource>) synchronized could solve the problem.

[Avishay]

hi... i'm using gate 7 ... and upgrading to gate 8 is impossible right now for us.... and we are facing a problem with the above bug .... is there any patch for it ?