Hi Aaron, I'm not sure if synchronizing on an arbitrary lock object would help. I suspect we will start seeing the ConcurrentModificationException again. The right fix has gone into Hadoop through 10456. Unfortunately, I don't have any bright ideas on how to synchronize this at the Spark level without the risk of deadlocks.
On Mon, Jul 14, 2014 at 3:07 PM, Aaron Davidson <ilike...@gmail.com> wrote: > The full jstack would still be useful, but our current working theory is > that this is due to the fact that Configuration#loadDefaults goes through > every Configuration object that was ever created (via > Configuration.REGISTRY) and locks it, thus introducing a dependency from > new Configuration to old, otherwise unrelated, Configuration objects that > our locking did not anticipate. > > I have created https://github.com/apache/spark/pull/1409 to hopefully fix > this bug. > > > On Mon, Jul 14, 2014 at 2:44 PM, Patrick Wendell <pwend...@gmail.com> > wrote: > > > Hey Cody, > > > > This Jstack seems truncated, would you mind giving the entire stack > > trace? For the second thread, for instance, we can't see where the > > lock is being acquired. > > > > - Patrick > > > > On Mon, Jul 14, 2014 at 1:42 PM, Cody Koeninger > > <cody.koenin...@mediacrossing.com> wrote: > > > Hi all, just wanted to give a heads up that we're seeing a reproducible > > > deadlock with spark 1.0.1 with 2.3.0-mr1-cdh5.0.2 > > > > > > If jira is a better place for this, apologies in advance - figured > > talking > > > about it on the mailing list was friendlier than randomly (re)opening > > jira > > > tickets. > > > > > > I know Gary had mentioned some issues with 1.0.1 on the mailing list, > > once > > > we got a thread dump I wanted to follow up. > > > > > > The thread dump shows the deadlock occurs in the synchronized block of > > code > > > that was changed in HadoopRDD.scala, for the Spark-1097 issue > > > > > > Relevant portions of the thread dump are summarized below, we can > provide > > > the whole dump if it's useful. > > > > > > Found one Java-level deadlock: > > > ============================= > > > "Executor task launch worker-1": > > > waiting to lock monitor 0x00007f250400c520 (object > 0x00000000fae7dc30, > > a > > > org.apache.hadoop.co > > > nf.Configuration), > > > which is held by "Executor task launch worker-0" > > > "Executor task launch worker-0": > > > waiting to lock monitor 0x00007f2520495620 (object > 0x00000000faeb4fc8, > > a > > > java.lang.Class), > > > which is held by "Executor task launch worker-1" > > > > > > > > > "Executor task launch worker-1": > > > at > > > > > > org.apache.hadoop.conf.Configuration.reloadConfiguration(Configuration.java:791) > > > - waiting to lock <0x00000000fae7dc30> (a > > > org.apache.hadoop.conf.Configuration) > > > at > > > > > > org.apache.hadoop.conf.Configuration.addDefaultResource(Configuration.java:690) > > > - locked <0x00000000faca6ff8> (a java.lang.Class for > > > org.apache.hadoop.conf.Configurati > > > on) > > > at > > > > > > org.apache.hadoop.hdfs.HdfsConfiguration.<clinit>(HdfsConfiguration.java:34) > > > at > > > > > > org.apache.hadoop.hdfs.DistributedFileSystem.<clinit>(DistributedFileSystem.java:110 > > > ) > > > at > sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native > > > Method) > > > at > > > > > > sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl. > > > java:57) > > > at > sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native > > > Method) > > > at > > > > > > sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl. > > > java:57) > > > at > > > > > > sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAcces > > > sorImpl.java:45) > > > at > > java.lang.reflect.Constructor.newInstance(Constructor.java:525) > > > at java.lang.Class.newInstance0(Class.java:374) > > > at java.lang.Class.newInstance(Class.java:327) > > > at > > java.util.ServiceLoader$LazyIterator.next(ServiceLoader.java:373) > > > at java.util.ServiceLoader$1.next(ServiceLoader.java:445) > > > at > > > org.apache.hadoop.fs.FileSystem.loadFileSystems(FileSystem.java:2364) > > > - locked <0x00000000faeb4fc8> (a java.lang.Class for > > > org.apache.hadoop.fs.FileSystem) > > > at > > > > org.apache.hadoop.fs.FileSystem.getFileSystemClass(FileSystem.java:2375) > > > at > > > org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:2392) > > > at > org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:89) > > > at > > > org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:2431) > > > at > > org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2413) > > > at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:368) > > > at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:167) > > > at > > > org.apache.hadoop.mapred.JobConf.getWorkingDirectory(JobConf.java:587) > > > at > > > > > > org.apache.hadoop.mapred.FileInputFormat.setInputPaths(FileInputFormat.java:315) > > > at > > > > > > org.apache.hadoop.mapred.FileInputFormat.setInputPaths(FileInputFormat.java:288) > > > at > > > org.apache.spark.SparkContext$$anonfun$22.apply(SparkContext.scala:546) > > > at > > > org.apache.spark.SparkContext$$anonfun$22.apply(SparkContext.scala:546) > > > at > > > > > > org.apache.spark.rdd.HadoopRDD$$anonfun$getJobConf$1.apply(HadoopRDD.scala:145) > > > > > > > > > > > > ...elided... > > > > > > > > > "Executor task launch worker-0" daemon prio=10 tid=0x0000000001e71800 > > > nid=0x2d97 waiting for monitor entry [0x00007f24d2bf1000] > > > java.lang.Thread.State: BLOCKED (on object monitor) > > > at > > > org.apache.hadoop.fs.FileSystem.loadFileSystems(FileSystem.java:2362) > > > - waiting to lock <0x00000000faeb4fc8> (a java.lang.Class for > > > org.apache.hadoop.fs.FileSystem) > > > at > > > > org.apache.hadoop.fs.FileSystem.getFileSystemClass(FileSystem.java:2375) > > > at > > > org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:2392) > > > at > org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:89) > > > at > > > org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:2431) > > > at > > org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2413) > > > at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:368) > > > at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:167) > > > at > > > org.apache.hadoop.mapred.JobConf.getWorkingDirectory(JobConf.java:587) > > > at > > > > > > org.apache.hadoop.mapred.FileInputFormat.setInputPaths(FileInputFormat.java:315) > > > at > > > > > > org.apache.hadoop.mapred.FileInputFormat.setInputPaths(FileInputFormat.java:288) > > > at > > > org.apache.spark.SparkContext$$anonfun$22.apply(SparkContext.scala:546) > > > at > > > org.apache.spark.SparkContext$$anonfun$22.apply(SparkContext.scala:546) > > > at > > > > > > org.apache.spark.rdd.HadoopRDD$$anonfun$getJobConf$1.apply(HadoopRDD.scala:145) > > >
