![](../images/icons/arrow_down.png)
!transporter.jpg|align=center!
h3. NioTransportProtocol
!NioTransportProtocol.jpg|align=center!
h2. PreExtensionsManager composite
Each pre-extension is instantiated dynamically before internal components when Petals ESB is started according to the content of the Petals ESB classloader.
!pre-extensions.jpg|align=center!
h3. EmbeddedRegistryOverlay composite
!embedded-registry-overlay.jpg|align=center!
h2. PostExtensionsManager composite
Each post-extension is instantiated dynamically after internal components y when Petals ESB is started according to the content of the Petals ESB classloader.
!post-extensions.jpg|align=center!
h3. Autoloader composite
!autoloader.jpg|align=center!
h3. Artifact repository composite
!artifactrepository.jpg|align=center!
h3. WsApi composite
!wsapi.jpg|align=center!
h1. Known problems
h2. Deadlock when starting a composite
*Symptoms*:
The startup of Petals blocks into the startup of the Fractal composite into the thread "main" with a similar thread dump:
{code}
"main" prio=10 tid=0x00007f83d4007800 nid=0x981 in Object.wait() [0x00007f83db58f000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000000c038a388> (a org.objectweb.fractal.julia.generated.Cbd2013d7_0)
at java.lang.Object.wait(Object.java:485)
at org.objectweb.fractal.julia.generated.Cbd2013d7_0.incrementFcInvocationCounter(BasicControllerMixin.java:4216)
at org.objectweb.fractal.julia.generated.Cec3b28ec_0.startScanner(INTERCEPTOR[DirectoryScanner])
- locked <0x00000000c038a388> (a org.objectweb.fractal.julia.generated.Cbd2013d7_0)
at org.objectweb.fractal.julia.generated.Cc2597297_0.startScanner(INTERFACE[DirectoryScanner])
at org.ow2.petals.jbi.management.autoload.AutoLoaderServiceImpl.start(AutoLoaderServiceImpl.java:221)
at org.ow2.petals.jbi.management.autoload.AutoLoaderServiceImpl.startFc(AutoLoaderServiceImpl.java)
at org.objectweb.fractal.julia.generated.Cbd2013d7_0.setFcContentState(BasicControllerMixin.java:8128)
at org.objectweb.fractal.julia.generated.Cbd2013d7_0.setFcStarted(BasicControllerMixin.java:8068)
- locked <0x00000000c038adc8> (a org.objectweb.fractal.julia.generated.Cbd2013d7_0)
at org.objectweb.fractal.julia.generated.C18c4c884_0.setFcStarted(INTERFACE[LifeCycleCoordinator])
at org.objectweb.fractal.julia.generated.C4eddf8e0_0.startFc$$0(BasicControllerMixin.java:4097)
at org.objectweb.fractal.julia.generated.C4eddf8e0_0.startFc(BasicControllerMixin.java:5095)
at org.objectweb.fractal.julia.generated.C18c4c884_0.startFc(INTERFACE[LifeCycleCoordinator])
at org.ow2.petals.kernel.server.FractalHelper.startComponent(FractalHelper.java:356)
at org.ow2.petals.kernel.server.PetalsServerImpl.startPetalsComposite(PetalsServerImpl.java:412)
at org.ow2.petals.kernel.server.PetalsServerImpl.start(PetalsServerImpl.java:186)
at org.ow2.petals.launcher.PetalsLauncher.launchPetalsServer(PetalsLauncher.java:154)
at org.ow2.petals.launcher.PetalsLauncher.main(PetalsLauncher.java:391)
{code}
*Solution*:
Update the ADL of the Fractal composite to [set the sub-components in the right order|#composite_startup].