Possible VM deadlock due to FileSystems.getDefault and System.loadLibrary interplay (original) (raw)

Vitaly Davidovich vitalyd at gmail.com
Wed Jan 3 17:13:52 UTC 2018

On Wed, Jan 3, 2018 at 12:00 PM, Alan Bateman <Alan.Bateman at oracle.com> wrote:

The stack trace looks like JDK 8 or older. The initialization has changed quite a bit in JDK 9+ and would be interesting to see if you can duplicate it there. Yes - it's 8u152 as I mentioned in the follow-up email (sorry, should've mentioned that initially).

Trying this on JDK9 is a bit tricky as the code (and its dependencies) in question isn't easily runnable on 9 without quite a bit of work.

Do you agree with the deadlock assessment though? That's what it looks like to me but wanted to make sure I'm not missing anything.

Thanks Alan

-Alan

On 03/01/2018 16:56, Vitaly Davidovich wrote: Hi all,

Consider the following stacktraces of the main app thread and a background thread: "main" #1 prio=5 osprio=0 tid=0x0000000001bfd000 nid=0x1958 waiting for monitor entry [0x00002b98ceba3000] java.lang.Thread.State: BLOCKED (on object monitor) at java.lang.Runtime.loadLibrary0(Runtime.java:862) - waiting to lock <0x00000007bf834b20> (a java.lang.Runtime) at java.lang.System.loadLibrary(System.java:1122) at sun.nio.fs.UnixNativeDispatcher$1.run( UnixNativeDispatcher.java:573) at sun.nio.fs.UnixNativeDispatcher$1.run( UnixNativeDispatcher.java:571) at java.security.AccessController.doPrivileged(Native Method) at sun.nio.fs.UnixNativeDispatcher.( UnixNativeDispatcher.java:571) at sun.nio.fs.UnixFileSystem.(UnixFileSystem.java:67) at sun.nio.fs.LinuxFileSystem.<_ _init>(LinuxFileSystem.java:39) at sun.nio.fs.LinuxFileSystemProvider.newFileSystem( LinuxFileSystemProvider.java:46) at sun.nio.fs.LinuxFileSystemProvider.newFileSystem( LinuxFileSystemProvider.java:39) at sun.nio.fs.UnixFileSystemProvider.( UnixFileSystemProvider.java:56) at sun.nio.fs.LinuxFileSystemProvider. (LinuxFileSystemProvider.java:41) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorA ccessorImpl.newInstance( NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorI mpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor. newInstance(Constructor.java:423) at java.lang.Class.newInstance(Class.java:442) at sun.nio.fs.DefaultFileSystemProvider.createProvider( DefaultFileSystemProvider.java:48) at sun.nio.fs.DefaultFileSystemProvider.create( DefaultFileSystemProvider.java:63) at java.nio.file.FileSystems$DefaultFileSystemHolder. getDefaultProvider(FileSystems.java:108) at java.nio.file.FileSystems$DefaultFileSystemHolder. access$000(FileSystems.java:89) at java.nio.file.FileSystems$Defa ultFileSystemHolder$1.run( FileSystems.java:98) at java.nio.file.FileSystems$Defa ultFileSystemHolder$1.run( FileSystems.java:96) at java.security.AccessController.doPrivileged(Native Method) at java.nio.file.FileSystems$DefaultFileSystemHolder. defaultFileSystem(FileSystems.java:96) at java.nio.file.FileSystems$DefaultFileSystemHolder.<_ _clinit>(FileSystems.java:90) at java.nio.file.FileSystems.getD efault(FileSystems.java: 176) at java.nio.file.Paths.get(Paths.java:84) at .ServiceLoader. setup(ServiceLoader.java:446) at .MetadataAdminLoader.main( MetadataAdminLoader.java:52)

"shardDbExecutor-0-pool-0" #33 prio=5 osprio=0 tid=0x0000000001ebf000 nid=0x1d01 in Object.wait() [0x00002b991f941000] java.lang.Thread.State: RUNNABLE at java.nio.file.FileSystems.getD efault(FileSystems.java: 176) at java.nio.file.Paths.get(Paths.java:138) at sun.misc.Launcher$ExtClassLoader.findLibrary( Launcher.java:224) at java.lang.ClassLoader.loadLibr ary(ClassLoader.java:1830) at java.lang.Runtime.loadLibrary0(Runtime.java:870) - locked <0x00000007bf834b20> (a java.lang.Runtime) at java.lang.System.loadLibrary(System.java:1122) at sun.security.ec.SunEC$1.run(SunEC.java:60) at sun.security.ec.SunEC$1.run(SunEC.java:58) at java.security.AccessController.doPrivileged(Native Method) at sun.security.ec.SunEC.(SunEC.java:58) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorA ccessorImpl.newInstance( NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorI mpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor. newInstance(Constructor.java:423) at java.lang.Class.newInstance(Class.java:442) at sun.security.jca.ProviderConfig$2.run( ProviderConfig.java:221) at sun.security.jca.ProviderConfig$2.run( ProviderConfig.java:206) at java.security.AccessController.doPrivileged(Native Method) at sun.security.jca.ProviderConfig.doLoadProvider( ProviderConfig.java:206) at sun.security.jca.ProviderConfig.getProvider( ProviderConfig.java:187) - locked <0x00000007bea03f48> (a sun.security.jca. ProviderConfig) at sun.security.jca.ProviderList. getProvider(ProviderList.java:233) at sun.security.jca.ProviderList. getService(ProviderList.java:331) at sun.security.jca.GetInstance. getInstance(GetInstance.java:157) at javax.net.ssl.SSLContext.getIn stance(SSLContext.java:156) at com.microsoft.sqlserver.jdbc. TDSChannel.enableSSL(IOBuffer.java:1658) at com.microsoft.sqlserver.jdbc.SQLServerConnection. connectHelper(SQLServerConnection.java:1976) at com.microsoft.sqlserver.jdbc.S QLServerConnection.login( SQLServerConnection.java:1627) at com.microsoft.sqlserver.jdbc.SQLServerConnection. connectInternal(SQLServerConnection.java:1458) at com.microsoft.sqlserver.jdbc.S QLServerConnection.connect( SQLServerConnection.java:772) at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect( SQLServerDriver.java:1168) at java.sql.DriverManager.getConnection(DriverManager. java:664) at java.sql.DriverManager.getConnection(DriverManager. java:208) at .ConnectionPool.createGoodConnection( ConnectionPool.java:565) at .ConnectionPool.createNewConnection( ConnectionPool.java:519) at .ConnectionPool. getConnection(ConnectionPool.java:407) at .StatementCachingConnectionImpl .setupConnection(StatementCachingConnectionImpl.java:94) at .StatementCachingConnectionImpl.( StatementCachingConnectionImpl.java:54) at .TestConnectionFactories$ FaultInjectingConnection.(TestConnectionFactories.java:90) at .TestConnectionF actories.lambda$static$3( TestConnectionFactories.java:33) at .TestConnectionFactories$$ Lambda$12/1738236591.newConnection(Unknown Source) at .SedaExecutor. setupConnections(SedaExecutor.java:130) at .SedaExecutor$SedaThreadFactory.lambda$ newThread$0(SedaExecutor.java:165) at .SedaExecutor$SedaThreadFactory$$Lambda$22/139 2419022.run(Unknown Source) at java.lang.Thread.run(Thread.java:748) The application intermittently hangs on startup, and the above callstacks are present. It seems like there's a deadlock due to concurrent class loading and default FileSystem initialization (which itself triggers class loading here). I wasn't able to find any existing JBS entries reporting anything similar. Am I seeing this right? Is this a known issue? Thanks

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