Hi everybody,

on our server running Wildfly-10.1.0.Final we're observing a weird behaviour. About once a day there are two or three threads consuming between 25-30% CPU load each and they keep running forever.

It's not clear what causes those threads to "go crazy" and what they are doing. The stack trace below doesn't really give any clue (at least not to me). Does anyone have an idea how to get to the root of the problem?

Thanks very much in advance!

Stack Trace

default task-56 [366] (RUNNABLE)

   org.xnio.conduits.StreamSinkChannelWrappingConduit.awaitWritable line: 99

   org.xnio.conduits.ConduitStreamSinkChannel.awaitWritable line: 134

   io.undertow.channels.DetachableStreamSinkChannel.awaitWritable line: 87

   io.undertow.server.HttpServerExchange$WriteDispatchChannel.awaitWritable line: 1962

   org.xnio.channels.Channels.writeBlocking line: 154

   io.undertow.servlet.spec.ServletOutputStreamImpl.write line: 283

   io.undertow.io.BlockingSenderImpl.writeBuffer line: 190

   io.undertow.io.BlockingSenderImpl.send line: 71

   io.undertow.server.handlers.resource.CachedResource.serve line: 187

   io.undertow.servlet.handlers.DefaultServlet.serveFileBlocking line: 332

   io.undertow.servlet.handlers.DefaultServlet.doGet line: 180

   javax.servlet.http.HttpServlet.service line: 687

   javax.servlet.http.HttpServlet.service line: 790

   io.undertow.servlet.handlers.ServletHandler.handleRequest line: 85

   io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest line: 62

   io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest line: 36

   org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest line: 78

   io.undertow.server.handlers.PredicateHandler.handleRequest line: 43

   io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest line: 131

   io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest line: 57

   io.undertow.server.handlers.PredicateHandler.handleRequest line: 43

   io.undertow.security.handlers.AuthenticationConstraintHandler.handleRequest line: 53

   io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest line: 46

   io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest line: 64

   io.undertow.servlet.handlers.security.ServletSecurityConstraintHandler.handleRequest line: 59

   io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest line: 60

   io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest line: 77

   io.undertow.security.handlers.NotificationReceiverHandler.handleRequest line: 50

   io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest line: 43

   io.undertow.server.handlers.PredicateHandler.handleRequest line: 43

   org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest line: 61

   io.undertow.server.handlers.PredicateHandler.handleRequest line: 43

   io.undertow.server.handlers.PredicateHandler.handleRequest line: 43

   io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest line: 292

   io.undertow.servlet.handlers.ServletInitialHandler.access$100 line: 81

   io.undertow.servlet.handlers.ServletInitialHandler$2.call line: 138

   io.undertow.servlet.handlers.ServletInitialHandler$2.call line: 135

   io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call line: 48

   io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call line: 43

   io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call line: 44

   io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call line: 44

   io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call line: 44

   io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call line: 44

   io.undertow.servlet.api.LegacyThreadSetupActionWrapper$1.call line: 44

   io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest line: 272

   io.undertow.servlet.handlers.ServletInitialHandler.access$000 line: 81

   io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest line: 104

   io.undertow.server.Connectors.executeRootHandler line: 202

   io.undertow.server.HttpServerExchange$1.run line: 805

   java.util.concurrent.ThreadPoolExecutor.runWorker line: 1142

   java.util.concurrent.ThreadPoolExecutor$Worker.run line: 617

   java.lang.Thread.run line: 745