Jetty 9.4.22 QueuedThreadPool compatibility

[josephlbarnett]

Per, jetty/jetty.project#4121 QueuedThreadPool implements ThreadFactory, which makes the newThread method public instead of protected. The JettyConnectorThreadPool class in JettyHttpContainerFactory has the newThread method marked as protected, and causes an IllegalAccessError when used at runtime (it also fails to compile if compiled against jetty 9.4.22):

java.lang.IllegalAccessError: 'java.lang.Thread org.glassfish.jersey.jetty.JettyHttpContainerFactory$JettyConnectorThreadPool.newThread(java.lang.Runnable)'
	at org.eclipse.jetty.util.thread.QueuedThreadPool.startThread(QueuedThreadPool.java:655)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.ensureThreads(QueuedThreadPool.java:642)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.doStart(QueuedThreadPool.java:182)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:72)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:169)
	at org.eclipse.jetty.server.Server.start(Server.java:407)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:117)
	at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:106)
	at org.eclipse.jetty.server.Server.doStart(Server.java:371)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:72)
	at org.glassfish.jersey.jetty.servlet.JettyWebContainerFactory.create(JettyWebContainerFactory.java:257)
	at org.glassfish.jersey.jetty.servlet.JettyWebContainerFactory.create(JettyWebContainerFactory.java:282)

[joakime]

You don't need to customize the QueuedThreadPool any more.
Use the java.util.concurrent.ThreadFactory itself, and pass it into the QueuedThreadPool constructor.

See: https://www.eclipse.org/jetty/javadoc/current/org/eclipse/jetty/util/thread/QueuedThreadPool.html#%3Cinit%3E(int,int,int,int,java.util.concurrent.BlockingQueue,java.lang.ThreadGroup,java.util.concurrent.ThreadFactory)

[jansupol]

I agree with making the method public. We probably should not rely on the new QueuedThreadPool constructor which is available in the latest Jetty only, yet, so that people can switch back to a previous version of Jetty, should they need it.

We may change it later.

[NielsDoucet]

@jansupol This incompatibility causes a bug for anyone using the spring-boot-dependencies bom as a baseline for version management (see spring-projects/spring-boot#19769).
In spring boot they are unable to change the minor version of both jetty and jersey due to various reasons (see linked ticket for details).

I asked about options on the jetty project (see jetty/jetty.project#4121), but in parallel I'd like to ask whether there is a possibility of a special 2.29.x release compatible with the new jetty API.