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https://issues.apache.org/jira/browse/LUCENE-6482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14575660#comment-14575660
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Uwe Schindler commented on LUCENE-6482:
---------------------------------------
>From digging around, the main problem is basically the following:
- The JVM requires that a parent clas smust be initialized before the child
class
- But there is a "special case": A parent class is allowed to initialize
subclasses from its static initializers (so stuff like our setup works). This
is documented in the JLS.
- But another thread is not allowed to initialize subclasses at the same time.
This basically leads to the deadlock we are seeing here. We have a not yet
fully initialized Codec parent class. The other thread is creating an instance
of a subclass directly. But while initializing this subclass, it waits for the
parent class to get available. But the parent class is currently scanning
classpath and creating instances of all available codecs. While doing this it
tries to create the class that the other thread is instantiating directly using
new(). And this is the deadlock.
> Class loading deadlock relating to NamedSPILoader
> -------------------------------------------------
>
> Key: LUCENE-6482
> URL: https://issues.apache.org/jira/browse/LUCENE-6482
> Project: Lucene - Core
> Issue Type: Bug
> Affects Versions: 4.9.1
> Reporter: Shikhar Bhushan
> Assignee: Uwe Schindler
> Attachments: CodecLoadingDeadlockTest.java
>
>
> This issue came up for us several times with Elasticsearch 1.3.4 (Lucene
> 4.9.1), with many threads seeming deadlocked but RUNNABLE:
> {noformat}
> "elasticsearch[search77-es2][generic][T#43]" #160 daemon prio=5 os_prio=0
> tid=0x00007f79180c5800 nid=0x3d1f in Object.wait() [0x00007f79d9289000]
> java.lang.Thread.State: RUNNABLE
> at org.apache.lucene.index.SegmentInfos.read(SegmentInfos.java:359)
> at org.apache.lucene.index.SegmentInfos$1.doBody(SegmentInfos.java:457)
> at
> org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:912)
> at
> org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:758)
> at org.apache.lucene.index.SegmentInfos.read(SegmentInfos.java:453)
> at
> org.elasticsearch.common.lucene.Lucene.readSegmentInfos(Lucene.java:98)
> at org.elasticsearch.index.store.Store.readSegmentsInfo(Store.java:126)
> at org.elasticsearch.index.store.Store.access$300(Store.java:76)
> at
> org.elasticsearch.index.store.Store$MetadataSnapshot.buildMetadata(Store.java:465)
> at
> org.elasticsearch.index.store.Store$MetadataSnapshot.<init>(Store.java:456)
> at
> org.elasticsearch.index.store.Store.readMetadataSnapshot(Store.java:281)
> at
> org.elasticsearch.indices.store.TransportNodesListShardStoreMetaData.listStoreMetaData(TransportNodesListShardStoreMetaData.java:186)
> at
> org.elasticsearch.indices.store.TransportNodesListShardStoreMetaData.nodeOperation(TransportNodesListShardStoreMetaData.java:140)
> at
> org.elasticsearch.indices.store.TransportNodesListShardStoreMetaData.nodeOperation(TransportNodesListShardStoreMetaData.java:61)
> at
> org.elasticsearch.action.support.nodes.TransportNodesOperationAction$NodeTransportHandler.messageReceived(TransportNodesOperationAction.java:277)
> at
> org.elasticsearch.action.support.nodes.TransportNodesOperationAction$NodeTransportHandler.messageReceived(TransportNodesOperationAction.java:268)
> at
> org.elasticsearch.transport.netty.MessageChannelHandler$RequestHandler.run(MessageChannelHandler.java:275)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> {noformat}
> It didn't really make sense to see RUNNABLE threads in Object.wait(), but
> this seems to be symptomatic of deadlocks in static initialization
> (http://ternarysearch.blogspot.ru/2013/07/static-initialization-deadlock.html).
> I found LUCENE-5573 as an instance of this having come up with Lucene code
> before.
> I'm not sure what exactly is going on, but the deadlock in this case seems to
> involve these threads:
> {noformat}
> "elasticsearch[search77-es2][clusterService#updateTask][T#1]" #79 daemon
> prio=5 os_prio=0 tid=0x00007f7b155ff800 nid=0xd49 in Object.wait()
> [0x00007f79daed8000]
> java.lang.Thread.State: RUNNABLE
> at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
> at
> sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
> at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
> at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
> at java.lang.Class.newInstance(Class.java:433)
> at org.apache.lucene.util.NamedSPILoader.reload(NamedSPILoader.java:67)
> - locked <0x000000061fef4968> (a org.apache.lucene.util.NamedSPILoader)
> at org.apache.lucene.util.NamedSPILoader.<init>(NamedSPILoader.java:47)
> at org.apache.lucene.util.NamedSPILoader.<init>(NamedSPILoader.java:37)
> at
> org.apache.lucene.codecs.PostingsFormat.<clinit>(PostingsFormat.java:44)
> at
> org.elasticsearch.index.codec.postingsformat.PostingFormats.<clinit>(PostingFormats.java:67)
> at
> org.elasticsearch.index.codec.CodecModule.configurePostingsFormats(CodecModule.java:126)
> at
> org.elasticsearch.index.codec.CodecModule.configure(CodecModule.java:178)
> at
> org.elasticsearch.common.inject.AbstractModule.configure(AbstractModule.java:60)
> - locked <0x000000061fef49e8> (a
> org.elasticsearch.index.codec.CodecModule)
> at
> org.elasticsearch.common.inject.spi.Elements$RecordingBinder.install(Elements.java:204)
> at
> org.elasticsearch.common.inject.spi.Elements.getElements(Elements.java:85)
> at
> org.elasticsearch.common.inject.InjectorShell$Builder.build(InjectorShell.java:130)
> at
> org.elasticsearch.common.inject.InjectorBuilder.build(InjectorBuilder.java:99)
> - locked <0x000000061fef4c10> (a
> org.elasticsearch.common.inject.InheritingState)
> at
> org.elasticsearch.common.inject.InjectorImpl.createChildInjector(InjectorImpl.java:131)
> at
> org.elasticsearch.common.inject.ModulesBuilder.createChildInjector(ModulesBuilder.java:69)
> at
> org.elasticsearch.indices.InternalIndicesService.createIndex(InternalIndicesService.java:296)
> - locked <0x000000061fef4cd0> (a
> org.elasticsearch.indices.InternalIndicesService)
> at
> org.elasticsearch.indices.cluster.IndicesClusterStateService.applyNewIndices(IndicesClusterStateService.java:312)
> at
> org.elasticsearch.indices.cluster.IndicesClusterStateService.clusterChanged(IndicesClusterStateService.java:181)
> - locked <0x000000061fef4e70> (a java.lang.Object)
> at
> org.elasticsearch.cluster.service.InternalClusterService$UpdateTask.run(InternalClusterService.java:444)
> at
> org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedEsThreadPoolExecutor.java:153)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> {noformat}
> {noformat}
> "elasticsearch[search77-es2][generic][T#1]" #80 daemon prio=5 os_prio=0
> tid=0x00007f794400a000 nid=0xd4b in Object.wait() [0x00007f79dac56000]
> java.lang.Thread.State: RUNNABLE
> at
> org.apache.lucene.codecs.simpletext.SimpleTextCodec.<init>(SimpleTextCodec.java:37)
> at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
> at
> sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
> at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
> at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
> at java.lang.Class.newInstance(Class.java:433)
> at org.apache.lucene.util.NamedSPILoader.reload(NamedSPILoader.java:67)
> - locked <0x000000061fcf1f50> (a org.apache.lucene.util.NamedSPILoader)
> at org.apache.lucene.util.NamedSPILoader.<init>(NamedSPILoader.java:47)
> at org.apache.lucene.util.NamedSPILoader.<init>(NamedSPILoader.java:37)
> at org.apache.lucene.codecs.Codec.<clinit>(Codec.java:41)
> at org.apache.lucene.index.SegmentInfos.read(SegmentInfos.java:359)
> at org.apache.lucene.index.SegmentInfos$1.doBody(SegmentInfos.java:457)
> at
> org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:912)
> at
> org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:758)
> at org.apache.lucene.index.SegmentInfos.read(SegmentInfos.java:453)
> at
> org.elasticsearch.common.lucene.Lucene.readSegmentInfos(Lucene.java:98)
> at org.elasticsearch.index.store.Store.readSegmentsInfo(Store.java:126)
> at org.elasticsearch.index.store.Store.access$300(Store.java:76)
> at
> org.elasticsearch.index.store.Store$MetadataSnapshot.buildMetadata(Store.java:465)
> at
> org.elasticsearch.index.store.Store$MetadataSnapshot.<init>(Store.java:456)
> at
> org.elasticsearch.index.store.Store.readMetadataSnapshot(Store.java:281)
> at
> org.elasticsearch.indices.store.TransportNodesListShardStoreMetaData.listStoreMetaData(TransportNodesListShardStoreMetaData.java:186)
> at
> org.elasticsearch.indices.store.TransportNodesListShardStoreMetaData.nodeOperation(TransportNodesListShardStoreMetaData.java:140)
> at
> org.elasticsearch.indices.store.TransportNodesListShardStoreMetaData.nodeOperation(TransportNodesListShardStoreMetaData.java:61)
> at
> org.elasticsearch.action.support.nodes.TransportNodesOperationAction$NodeTransportHandler.messageReceived(TransportNodesOperationAction.java:277)
> at
> org.elasticsearch.action.support.nodes.TransportNodesOperationAction$NodeTransportHandler.messageReceived(TransportNodesOperationAction.java:268)
> at
> org.elasticsearch.transport.netty.MessageChannelHandler$RequestHandler.run(MessageChannelHandler.java:275)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> {noformat}
> Full thread dump: https://gist.github.com/shikhar/d0f6d2d008f45d2d4f91
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