https://issues.apache.org/bugzilla/show_bug.cgi?id=56530
Bug ID: 56530
Summary: WebappClassLoader.loadClass synchronization issue due
to coarse lock at WebappClassLoader instance level
instead of been by class name
Product: Tomcat 7
Version: 7.0.53
Hardware: PC
Status: NEW
Severity: major
Priority: P2
Component: Catalina
Assignee: dev@tomcat.apache.org
Reporter: sebtar...@ncf.ca
I'm having some visible performance issue related to the use of method
synchronized loadClass(String name, boolean resolve) in WebappClassLoader
I see that the author or at least some of the author(s) of the class
WebappClassLoader got the idea in other cases of a more specialize lock than
WebappClassLoader instance.
Should we just lock here using the name of the class we are looking for?
Also we should probably make the distinction between read and write.
The scenario here, is classic cache factory synchronization. So we could just
copy the right locking pattern from other sources.
My partial threads stack dump:
2014-05-14 12:36:01
Full thread dump Java HotSpot(TM) 64-Bit Server VM (20.45-b01 mixed mode):
"http-bio-31680-exec-57" - Thread t@124
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
...
"http-bio-31680-exec-56" - Thread t@123
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-55" - Thread t@122
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
Locked ownable synchronizers:
- locked <444b3957> (a
java.util.concurrent.locks.ReentrantLock$NonfairSync)
"http-bio-31680-exec-54" - Thread t@121
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.findProviderClass(ObjectFactory.java:358)
"http-bio-31680-exec-53" - Thread t@120
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-52" - Thread t@119
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-51" - Thread t@118
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at javax.xml.parsers.FactoryFinder.getProviderClass(FactoryFinder.java:119)
"http-bio-31680-exec-50" - Thread t@117
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-49" - Thread t@116
java.lang.Thread.State: RUNNABLE
at java.lang.Class.getClassLoader0(Native Method)
at java.lang.Class.getClassLoader(Class.java:589)
at
com.sun.xml.internal.bind.v2.model.annotation.LocatableAnnotation.create(LocatableAnnotation.java:63)
at
com.sun.xml.internal.bind.v2.model.annotation.RuntimeInlineAnnotationReader.getAllFieldAnnotations(RuntimeInlineAnnotationReader.java:60)
at
com.sun.xml.internal.bind.v2.model.annotation.RuntimeInlineAnnotationReader.getAllFieldAnnotations(RuntimeInlineAnnotationReader.java:42)
"http-bio-31680-exec-48" - Thread t@115
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at javax.xml.bind.ContextFinder.safeLoadClass(ContextFinder.java:481)
"http-bio-31680-exec-47" - Thread t@114
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at javax.xml.parsers.FactoryFinder.getProviderClass(FactoryFinder.java:119)
"http-bio-31680-exec-46" - Thread t@113
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-45" - Thread t@112
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:47)
"http-bio-31680-exec-44" - Thread t@111
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.findProviderClass(ObjectFactory.java:358)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.newInstance(ObjectFactory.java:303)
"http-bio-31680-exec-43" - Thread t@110
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.findProviderClass(ObjectFactory.java:358)
"http-bio-31680-exec-42" - Thread t@109
java.lang.Thread.State: TIMED_WAITING
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <2aa68578> (a
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:196)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2025)
at
java.util.concurrent.LinkedBlockingQueue.poll(LinkedBlockingQueue.java:424)
at org.apache.tomcat.util.threads.TaskQueue.poll(TaskQueue.java:86)
at org.apache.tomcat.util.threads.TaskQueue.poll(TaskQueue.java:32)
at
java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:955)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:917)
at java.lang.Thread.run(Thread.java:662)
Locked ownable synchronizers:
- None
"http-bio-31680-exec-40" - Thread t@107
java.lang.Thread.State: TIMED_WAITING
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <2aa68578> (a
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:196)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2025)
at
java.util.concurrent.LinkedBlockingQueue.poll(LinkedBlockingQueue.java:424)
at org.apache.tomcat.util.threads.TaskQueue.poll(TaskQueue.java:86)
at org.apache.tomcat.util.threads.TaskQueue.poll(TaskQueue.java:32)
at
java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:955)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:917)
at java.lang.Thread.run(Thread.java:662)
Locked ownable synchronizers:
- None
"http-bio-31680-exec-39" - Thread t@106
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.findProviderClass(ObjectFactory.java:358)
"http-bio-31680-exec-38" - Thread t@105
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at javax.xml.parsers.FactoryFinder.getProviderClass(FactoryFinder.java:119)
at javax.xml.parsers.FactoryFinder.newInstance(FactoryFinder.java:154)
at javax.xml.parsers.FactoryFinder.find(FactoryFinder.java:241)
"http-bio-31680-exec-37" - Thread t@104
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:47)
at
com.sun.xml.internal.bind.v2.model.impl.ModelBuilder.loadObjectFactory(ModelBuilder.java:249)
"http-bio-31680-exec-36" - Thread t@103
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.findProviderClass(ObjectFactory.java:358)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.newInstance(ObjectFactory.java:303)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.newInstance(ObjectFactory.java:289)
"http-bio-31680-exec-35" - Thread t@102
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-34" - Thread t@101
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-33" - Thread t@100
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-32" - Thread t@99
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.findProviderClass(ObjectFactory.java:358)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.newInstance(ObjectFactory.java:303)
"http-bio-31680-exec-31" - Thread t@98
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at javax.xml.parsers.FactoryFinder.getProviderClass(FactoryFinder.java:119)
at javax.xml.parsers.FactoryFinder.newInstance(FactoryFinder.java:154)
"http-bio-31680-exec-30" - Thread t@97
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at javax.xml.bind.ContextFinder.safeLoadClass(ContextFinder.java:481)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:185)
"http-bio-31680-exec-29" - Thread t@96
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
"http-bio-31680-exec-28" - Thread t@95
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at javax.xml.parsers.FactoryFinder.getProviderClass(FactoryFinder.java:119)
at javax.xml.parsers.FactoryFinder.newInstance(FactoryFinder.java:154)
"http-bio-31680-exec-27" - Thread t@94
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at javax.xml.parsers.FactoryFinder.getProviderClass(FactoryFinder.java:119)
"http-bio-31680-exec-26" - Thread t@93
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:505)
at
com.sun.xml.internal.bind.v2.model.nav.ReflectionNavigator.findClass(ReflectionNavigator.java:47)
"http-bio-31680-exec-25" - Thread t@92
java.lang.Thread.State: BLOCKED
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1605)
- waiting to lock <264d40df> (a
org.apache.catalina.loader.WebappClassLoader) owned by "http-bio-31680-exec-41"
t@108
at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.findProviderClass(ObjectFactory.java:358)
at
com.sun.org.apache.xerces.internal.utils.ObjectFactory.newInstance(ObjectFactory.java:303)
.. and more
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