Deadlock between reclaimCapacity and assignTasks
------------------------------------------------
Key: HADOOP-4977
URL: https://issues.apache.org/jira/browse/HADOOP-4977
Project: Hadoop Core
Issue Type: Bug
Components: contrib/capacity-sched
Reporter: Matei Zaharia
I was running the latest trunk with the capacity scheduler and saw the
JobTracker lock up with the following deadlock reported in jstack:
Found one Java-level deadlock:
=============================
"18107...@qtp0-4":
waiting to lock monitor 0x08085b40 (object 0x56605100, a
org.apache.hadoop.mapred.JobTracker),
which is held by "IPC Server handler 4 on 54311"
"IPC Server handler 4 on 54311":
waiting to lock monitor 0x0808594c (object 0x5660e518, a
org.apache.hadoop.mapred.CapacityTaskScheduler$MapSchedulingMgr),
which is held by "reclaimCapacity"
"reclaimCapacity":
waiting to lock monitor 0x08085b40 (object 0x56605100, a
org.apache.hadoop.mapred.JobTracker),
which is held by "IPC Server handler 4 on 54311"
Java stack information for the threads listed above:
===================================================
"18107...@qtp0-4":
at
org.apache.hadoop.mapred.JobTracker.getClusterStatus(JobTracker.java:2695)
- waiting to lock <0x56605100> (a org.apache.hadoop.mapred.JobTracker)
at
org.apache.hadoop.mapred.jobtracker_jsp._jspService(jobtracker_jsp.java:93)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at
org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:502)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:363)
at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:417)
at
org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:324)
at
org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:534)
at
org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:864)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:533)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:207)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:403)
at
org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at
org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:522)
"IPC Server handler 4 on 54311":
at
org.apache.hadoop.mapred.CapacityTaskScheduler$TaskSchedulingMgr.updateQSIObjects(CapacityTaskScheduler.java:564)
- waiting to lock <0x5660e518> (a
org.apache.hadoop.mapred.CapacityTaskScheduler$MapSchedulingMgr)
at
org.apache.hadoop.mapred.CapacityTaskScheduler$TaskSchedulingMgr.assignTasks(CapacityTaskScheduler.java:855)
at
org.apache.hadoop.mapred.CapacityTaskScheduler$TaskSchedulingMgr.access$1000(CapacityTaskScheduler.java:294)
at
org.apache.hadoop.mapred.CapacityTaskScheduler.assignTasks(CapacityTaskScheduler.java:1336)
- locked <0x5660dd20> (a org.apache.hadoop.mapred.CapacityTaskScheduler)
at org.apache.hadoop.mapred.JobTracker.heartbeat(JobTracker.java:2288)
- locked <0x56605100> (a org.apache.hadoop.mapred.JobTracker)
at sun.reflect.GeneratedMethodAccessor16.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:508)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:959)
Unfortunately I didn't manage to select all of the output by mistake, so some
is missing, but it appears that reclaimCapacity locks the MapSchedulingMgr and
then tries to lock the JobTracker, whereas the updateQSIObjects called in
assignTasks holds a lock on the JobTracker (the JobTracker grabs this lock when
it calls assignTasks) and then tries to lock the MapSchedulingMgr. The other
thread listed there is a Jetty thread for the web interface and isn't part of
the circular locking. The solution to this would be to lock the JobTracker in
reclaimCapacity before locking anything else.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
