Restlet hangs on Engine.getInstance

[jonfinanger]

I have to modules (different threads) accessing restlet api in my java application. The first module uses the ClientResource and connects to a remte server. The other acts as a restserver using new Component() waiting for requests.....

The modules starts about at the same time. Once a while i experience a "freeze" in the startup of the modules. And the stacktrace shows this every time it hangs:

Module 1:
#46 daemon prio=5 os_prio=0 tid=0x15e72000 nid=0x3444 waiting for monitor entry [0x1684f000] java.lang.Thread.State: BLOCKED (on object monitor) at org.restlet.engine.Engine.getInstance(Engine.java:249) - waiting to lock <0x09938838> (a java.lang.Class for org.restlet.engine.Engine) at org.restlet.data.Method.<clinit>(Method.java:337) at org.restlet.resource.ClientResource.<init>(ClientResource.java:396)

Module2:
#50 daemon prio=5 os_prio=0 tid=0x15e6f400 nid=0x3774 in Object.wait() [0x167bf000] java.lang.Thread.State: RUNNABLE at org.restlet.engine.connector.HttpProtocolHelper.registerMethods(HttpProtocolHelper.java:39) at org.restlet.engine.connector.ProtocolHelper.<init>(ProtocolHelper.java:42) at org.restlet.engine.connector.HttpProtocolHelper.<init>(HttpProtocolHelper.java:35) at org.restlet.engine.Engine.registerDefaultProtocols(Engine.java:867) at org.restlet.engine.Engine.discoverProtocols(Engine.java:680) at org.restlet.engine.Engine.<init>(Engine.java:492) at org.restlet.engine.Engine.register(Engine.java:382) - locked <0x09938838> (a java.lang.Class for org.restlet.engine.Engine) at org.restlet.engine.Engine.register(Engine.java:368) - locked <0x09938838> (a java.lang.Class for org.restlet.engine.Engine) at org.restlet.engine.Engine.getInstance(Engine.java:252) - locked <0x09938838> (a java.lang.Class for org.restlet.engine.Engine) at org.restlet.Restlet.<init>(Restlet.java:122) at org.restlet.Restlet.<init>(Restlet.java:99) at org.restlet.Component.<init>(Component.java:173)

The first thread is waiting for the second in a blocked state. It looks to me that the second thread is causing the blocking, but i'm not clear on why the second thread never releases the monitor

[Tembrel]

What Restlet version is this? I see some problems with the most recent code, but I don't see an Object.wait in HttpProtocolHelper.registerMethods.

To work around this, call Engine.getInstance in each thread before calling any other Restlet methods.

Restlet folks: Probably best not to use static synchronized to guard access to the singleton. Also, the call to an abstract method in the constructor of ProtocolHelper looks a bit dicey.