# ModuleClassLoader Deadlock **URL:** \ **Category:** Module Development\ **Tags:** ignition81\ **Created:** [November 17, 2022, 5:48pm UTC](https://forum.inductiveautomation.com/t/moduleclassloader-deadlock/66646 "2022-11-17T17:48:35Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![cody.tamaki](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cody.tamaki](https://forum.inductiveautomation.com/u/cody.tamaki)\ **Post date:** [November 17, 2022, 5:48pm UTC](https://forum.inductiveautomation.com/t/moduleclassloader-deadlock/66646/1 "2022-11-17T17:48:35Z")
Hello, I've got a module of mine using a REST API from the Ignition gateway, and I keep leaking database connections due to dead-locked threads from the Ignition Module class loader. Is there any way around this? Should I force this thread to use a separate class loader? Full thread-dump of one of the dead-locked threads below. ``` { "name": "webserver-10520231", "id": 10520231, "state": "RUNNABLE", "daemon": false, "system": "Web API", "scope": "Gateway", "cpuUsage": 0, "lockedMonitors": [ { "lock": "com.inductiveautomation.ignition.gateway.modules.NativeLibraryManagerImpl@4c686005", "frame": "java.base@11.0.15/java.lang.ClassLoader.loadClass(Unknown Source)" }, { "lock": "com.inductiveautomation.ignition.gateway.modules.ModuleClassLoader@3e2f0cef", "frame": "java.base@11.0.15/java.lang.ClassLoader.loadClass(Unknown Source)" }, { "lock": "com.inductiveautomation.ignition.gateway.modules.ModuleClassLoader@17281723" } ], "stacktrace": [ "java.base@11.0.15/java.lang.ClassLoader.loadClass(Unknown Source)", "java.base@11.0.15/java.lang.ClassLoader.loadClass(Unknown Source)", "app//com.inductiveautomation.ignition.gateway.modules.ModuleClassLoader.loadClass(ModuleClassLoader.java:85)", "app//com.inductiveautomation.ignition.gateway.modules.ModuleClassLoader.loadClass(ModuleClassLoader.java:93)", "java.base@11.0.15/java.lang.ClassLoader.loadClass(Unknown Source)", "java.base@11.0.15/java.lang.Class.forName0(Native Method)", "java.base@11.0.15/java.lang.Class.forName(Unknown Source)", "org.hibernate.validator.internal.util.privilegedactions.LoadClass.loadNonValidatorClass(LoadClass.java:118)", "org.hibernate.validator.internal.util.privilegedactions.LoadClass.run(LoadClass.java:76)", "org.hibernate.validator.internal.util.privilegedactions.LoadClass.run(LoadClass.java:31)", "org.hibernate.validator.internal.metadata.core.ConstraintHelper.run(ConstraintHelper.java:1022)", "org.hibernate.validator.internal.metadata.core.ConstraintHelper.isClassPresent(ConstraintHelper.java:1007)", "org.hibernate.validator.internal.metadata.core.ConstraintHelper.isJavaMoneyInClasspath(ConstraintHelper.java:974)", "org.hibernate.validator.internal.metadata.core.ConstraintHelper.(ConstraintHelper.java:324)", "org.hibernate.validator.internal.engine.ValidatorFactoryImpl.(ValidatorFactoryImpl.java:146)", "org.hibernate.validator.HibernateValidator.buildValidatorFactory(HibernateValidator.java:38)", "org.hibernate.validator.internal.engine.ConfigurationImpl.buildValidatorFactory(ConfigurationImpl.java:386)", "javax.validation.Validation.buildDefaultValidatorFactory(Validation.java:103)", "com.tamakicontrol.service.model.AbstractCrudService.createValidator(AbstractCrudService.java:46)", "com.tamakicontrol.service.model.AbstractCrudService.(AbstractCrudService.java:39)", "com.tamakicontrol.service.model.productionmodel.ProductionModelService.(ProductionModelService.java:44)", "com.tamakicontrol.service.model.productionmodel.ProductionModelService$$EnhancerByGuice$$36026832.()", "com.tamakicontrol.service.model.productionmodel.ProductionModelService$$EnhancerByGuice$$36026832.GUICE$TRAMPOLINE()", "com.tamakicontrol.service.model.productionmodel.ProductionModelService$$EnhancerByGuice$$36026832$$Lambda$10844/0x000000080378cc40.apply(Unknown Source)", "com.google.inject.internal.ProxyFactory$ProxyConstructor.newInstance(ProxyFactory.java:183)", "com.google.inject.internal.ConstructorInjector.provision(ConstructorInjector.java:114)", "com.google.inject.internal.ConstructorInjector.construct(ConstructorInjector.java:91)", "com.google.inject.internal.ConstructorBindingImpl$Factory.get(ConstructorBindingImpl.java:300)", "com.google.inject.internal.SingleParameterInjector.inject(SingleParameterInjector.java:40)", "com.google.inject.internal.SingleParameterInjector.getAll(SingleParameterInjector.java:60)", "com.google.inject.internal.ConstructorInjector.provision(ConstructorInjector.java:113)", "com.google.inject.internal.ConstructorInjector.construct(ConstructorInjector.java:91)", "com.google.inject.internal.ConstructorBindingImpl$Factory.get(ConstructorBindingImpl.java:300)", "com.google.inject.internal.SingleParameterInjector.inject(SingleParameterInjector.java:40)", "com.google.inject.internal.SingleParameterInjector.getAll(SingleParameterInjector.java:60)", "com.google.inject.internal.ConstructorInjector.provision(ConstructorInjector.java:113)", "com.google.inject.internal.ConstructorInjector.construct(ConstructorInjector.java:91)", "com.google.inject.internal.ConstructorBindingImpl$Factory.get(ConstructorBindingImpl.java:300)", "com.google.inject.internal.SingleParameterInjector.inject(SingleParameterInjector.java:40)", "com.google.inject.internal.SingleParameterInjector.getAll(SingleParameterInjector.java:60)", "com.google.inject.internal.ConstructorInjector.provision(ConstructorInjector.java:113)", "com.google.inject.internal.ConstructorInjector.construct(ConstructorInjector.java:91)", "com.google.inject.internal.ConstructorBindingImpl$Factory.get(ConstructorBindingImpl.java:300)", "com.google.inject.internal.InjectorImpl$1.get(InjectorImpl.java:1101)", "org.jvnet.hk2.guice.bridge.internal.GuiceServiceHk2Bean.create(GuiceServiceHk2Bean.java:90)", "org.jvnet.hk2.internal.SystemDescriptor.create(SystemDescriptor.java:455)", "org.jvnet.hk2.guice.bridge.internal.GuiceScopeContext.findOrCreate(GuiceScopeContext.java:51)", "org.jvnet.hk2.internal.Utilities.createService(Utilities.java:2102)", "org.jvnet.hk2.internal.ServiceLocatorImpl.getService(ServiceLocatorImpl.java:666)", "org.jvnet.hk2.internal.ThreeThirtyResolver.resolve(ThreeThirtyResolver.java:54)", "org.jvnet.hk2.internal.ClazzCreator.resolve(ClazzCreator.java:188)", "org.jvnet.hk2.internal.ClazzCreator.resolveAllDependencies(ClazzCreator.java:211)", "org.jvnet.hk2.internal.ClazzCreator.create(ClazzCreator.java:334)", "org.jvnet.hk2.internal.SystemDescriptor.create(SystemDescriptor.java:463)", "org.glassfish.jersey.inject.hk2.RequestContext.findOrCreate(RequestContext.java:59)", "org.jvnet.hk2.internal.Utilities.createService(Utilities.java:2102)", "org.jvnet.hk2.internal.ServiceLocatorImpl.internalGetService(ServiceLocatorImpl.java:758)", "org.jvnet.hk2.internal.ServiceLocatorImpl.internalGetService(ServiceLocatorImpl.java:721)", "org.jvnet.hk2.internal.ServiceLocatorImpl.getService(ServiceLocatorImpl.java:691)", "org.glassfish.jersey.inject.hk2.AbstractHk2InjectionManager.getInstance(AbstractHk2InjectionManager.java:160)", "org.glassfish.jersey.inject.hk2.ImmediateHk2InjectionManager.getInstance(ImmediateHk2InjectionManager.java:30)", "org.glassfish.jersey.internal.inject.Injections.getOrCreate(Injections.java:105)", "org.glassfish.jersey.server.model.MethodHandler$ClassBasedMethodHandler.getInstance(MethodHandler.java:260)", "org.glassfish.jersey.server.internal.routing.PushMethodHandlerRouter.apply(PushMethodHandlerRouter.java:51)", "org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:86)", "org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:89)", "org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:89)", "org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:89)", "org.glassfish.jersey.server.internal.routing.RoutingStage.apply(RoutingStage.java:69)", "org.glassfish.jersey.server.internal.routing.RoutingStage.apply(RoutingStage.java:38)", "org.glassfish.jersey.process.internal.Stages.process(Stages.java:173)", "org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:247)", "org.glassfish.jersey.internal.Errors$1.call(Errors.java:248)", "org.glassfish.jersey.internal.Errors$1.call(Errors.java:244)", "org.glassfish.jersey.internal.Errors.process(Errors.java:292)", "org.glassfish.jersey.internal.Errors.process(Errors.java:274)", "org.glassfish.jersey.internal.Errors.process(Errors.java:244)", "org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:265)", "org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:234)", "org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:680)", "org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:394)", "org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:346)", "org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:366)", "org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:319)", "org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:205)", "app//com.inductiveautomation.ignition.gateway.bootstrap.MapServlet.service(MapServlet.java:86)", "app//org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1450)", "app//org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799)", "app//org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1631)", "app//org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:548)", "app//org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)", "app//org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:600)", "app//org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)", "app//org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)", "app//org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624)", "app//org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)", "app//org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1440)", "app//org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)", "app//org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501)", "app//org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594)" ] }, ``` ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [November 17, 2022, 5:50pm UTC](https://forum.inductiveautomation.com/t/moduleclassloader-deadlock/66646/2 "2022-11-17T17:50:13Z")
Are you sure you have a deadlock? You've only posted one thread. Does the full thread dump actually indicate a deadlock between 2 or more threads at the top? ---
**Author:** ![cody.tamaki](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cody.tamaki](https://forum.inductiveautomation.com/u/cody.tamaki)\ **Post date:** [November 21, 2022, 8:28pm UTC](https://forum.inductiveautomation.com/t/moduleclassloader-deadlock/66646/3 "2022-11-21T20:28:18Z")
Sorry it was my mistake... I think I just happened to grab a copy of a thread dump that showed 2 different threads queuing for the same lock and I didn't notice it. No deadlocks though.