Following JIRA explains the above problem found in 4.1.0-alpha: https://issues.apache.org/jira/browse/STRATOS-1089
On Tue, Jan 20, 2015 at 6:50 PM, Imesh Gunaratne <[email protected]> wrote: > Hi Devs, > > Currently we have significant amount of read write locks in Stratos > codebase to synchronize data structure updates made by multiple threads. > > As I figured out recently there are several possibilities that these locks > could cause problems if not properly implemented: > > *Problem 1: A thread trying to acquire a write lock while having a read > lock.* > *Problem 2: Locks acquired but not released* > > I just implemented a ReadWriteLock class in stratos common module which > could detect these problems. This class make use > of java.util.concurrent.locks.ReentrantReadWriteLock and implements > additional logic to detect problems. By default problem 2 detection logic > is disabled, it can be enabled by setting following system property: > > > *read.write.lock.monitor.enabled=true* > > I have now updated all read write locks with the above class. > Following is an example scenario where I detected an unreleased lock in > the REST API: > > org.apache.stratos.common.exception.LockNotReleasedException > at > org.apache.stratos.common.concurrent.locks.ReadWriteLockMonitor.checkTimeout(ReadWriteLockMonitor.java:71) > at > org.apache.stratos.common.concurrent.locks.ReadWriteLockMonitor.run(ReadWriteLockMonitor.java:50) > at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) > at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304) > at > java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178) > at > java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) > at > java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) > at > java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) > at java.lang.Thread.run(Thread.java:745) > [2015-01-20 18:30:12,952] ERROR > {org.apache.stratos.common.concurrent.locks.ReadWriteLockMonitor} - System > error, lock has not released for 30 seconds: [lock-name] topology > [lock-type] Read [thread-id] 405 [thread-name] http-nio-9443-exec-21 > [stack-trace] > java.lang.Thread.getStackTrace(Thread.java:1589) > > org.apache.stratos.common.concurrent.locks.ReadWriteLock.acquireReadLock(ReadWriteLock.java:160) > > org.apache.stratos.messaging.message.receiver.topology.TopologyManager.acquireReadLockForCluster(TopologyManager.java:173) > > org.apache.stratos.rest.endpoint.api.StratosApiV41Utils.addClustersInstancesToGroupInstanceBean(StratosApiV41Utils.java:1015) > > org.apache.stratos.rest.endpoint.api.StratosApiV41Utils.setSubGroupInstances(StratosApiV41Utils.java:1027) > > org.apache.stratos.rest.endpoint.api.StratosApiV41Utils.addGroupsInstancesToApplicationInstanceBean(StratosApiV41Utils.java:979) > > org.apache.stratos.rest.endpoint.api.StratosApiV41Utils.getApplicationRuntime(StratosApiV41Utils.java:963) > > org.apache.stratos.rest.endpoint.api.StratosApiV41.getApplicationRuntime(StratosApiV41.java:579) > > Thanks > > > -- > Imesh Gunaratne > > Technical Lead, WSO2 > Committer & PMC Member, Apache Stratos > -- Imesh Gunaratne Technical Lead, WSO2 Committer & PMC Member, Apache Stratos
