JBoss threads hung in Http2StreamSinkChannel and AbstractFramedStreamSinkChannel.awaitWritable

Issue

• JBoss is becoming unresponsive with request threads exhausted and persisting in Http2StreamSinkChannel/AbstractFramedStreamSinkChannel.awaitWritable calls:

"default task-21293" #37774 prio=5 os_prio=0 tid=0x000000004ac58800 nid=0x2644 in Object.wait() [0x00000000796de000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
    at java.lang.Object.wait(Native Method)
    at io.undertow.server.protocol.framed.AbstractFramedStreamSinkChannel.awaitWritable(AbstractFramedStreamSinkChannel.java:301)
    - locked <0x00000006721ad108> (a java.lang.Object)
    at io.undertow.protocols.http2.Http2StreamSinkChannel.awaitWritable(Http2StreamSinkChannel.java:186)
    at org.xnio.conduits.StreamSinkChannelWrappingConduit.awaitWritable(StreamSinkChannelWrappingConduit.java:99)
    at org.xnio.conduits.AbstractSinkConduit.awaitWritable(AbstractSinkConduit.java:66)
    at org.xnio.conduits.ConduitStreamSinkChannel.awaitWritable(ConduitStreamSinkChannel.java:134)
    at io.undertow.channels.DetachableStreamSinkChannel.awaitWritable(DetachableStreamSinkChannel.java:87)
    at io.undertow.server.HttpServerExchange$WriteDispatchChannel.awaitWritable(HttpServerExchange.java:2052)