be more careful about terminating multi stream threads

bubble-server/src/main/java/bubble/service/stream/ActiveStreamState.java

@@ -14,6 +14,7 @@ import org.cobbzilla.util.http.HttpContentEncodingType;
 import org.cobbzilla.util.io.FilterInputStreamViaOutputStream;
 import org.cobbzilla.util.io.FixedByteArrayInputStream;
 import org.cobbzilla.util.io.multi.MultiStream;
+import org.cobbzilla.util.io.multi.MultiUnderflowHandlerMonitor;
 import org.cobbzilla.util.system.Bytes;
 
 import java.io.ByteArrayInputStream;
@@ -39,6 +40,22 @@ class ActiveStreamState {
     // this avoids errors when creating a GZIPInputStream when only one or a few bytes are available
     public static final long MIN_BYTES_BEFORE_WRAP = Bytes.KB;
 
+    static {
+        // do not terminate threads that are idling just fine
+        // only terminate threads with abnormally long or short stacks
+        MultiUnderflowHandlerMonitor.DEFAULT_UNDERFLOW_MONITOR.setTerminateThreadFunc(t -> {
+            final StackTraceElement[] stack = t.getStackTrace();
+            if (stack.length < 5) return false;
+            if (stack.length > 15) return true;
+            for (int i=0; i<5; i++) {
+                if (stack[i].toString().contains("org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run")) {
+                    return false;
+                }
+            }
+            return true;
+        });
+    }
+
     private final FilterHttpRequest request;
     private final String requestId;
     private final AppRuleHarness firstRule;

utils/cobbzilla-utils

@@ -1 +1 @@
-Subproject commit 5165445487522986bb7c112e2b41a3563c6b9b69
+Subproject commit 9481a2c0a68e50d6ad3b984b77f41ce0a57de963