fix: Python embedded server should shut down any jvm threads/work it …

…can (deephaven#6006)

Fixes deephaven#6005

py/embedded-server/build.gradle

@@ -27,7 +27,7 @@ dependencies {
     }
 }
 
-def testPyClient = Docker.registerDockerTask(project, 'testPyClient') {
+def testEmbeddedServer = Docker.registerDockerTask(project, 'testEmbeddedServer') {
     copyIn {
         from('tests') {
             into 'project/tests'
@@ -62,4 +62,4 @@ def testPyClient = Docker.registerDockerTask(project, 'testPyClient') {
     }
 }
 
-tasks.getByName('check').dependsOn(testPyClient)
+tasks.getByName('check').dependsOn(testEmbeddedServer)

py/embedded-server/deephaven_server/server.py

@@ -5,6 +5,7 @@
 
 from typing import List, Optional
 import sys
+import atexit
 
 from .start_jvm import start_jvm
 
@@ -167,6 +168,9 @@ def __init__(
         # Keep a reference to the server so we know it is running
         Server.instance = self
 
+        # On halt, prevent the JVM from writing to sys.out and sys.err
+        atexit.register(self.j_server.prepareForShutdown)
+
     def start(self):
         """
         Starts the server. Presently once the server is started, it cannot be stopped until the

py/embedded-server/java-runtime/src/main/java/io/deephaven/python/server/EmbeddedServer.java

@@ -36,6 +36,7 @@
 import io.deephaven.server.session.ObfuscatingErrorTransformerModule;
 import io.deephaven.server.session.SslConfigModule;
 import io.deephaven.time.calendar.CalendarsFromConfigurationModule;
+import io.deephaven.util.process.ProcessEnvironment;
 import org.jpy.PyModule;
 import org.jpy.PyObject;
 
@@ -167,6 +168,15 @@ public void start() throws Exception {
         Bootstrap.printf("Server started on port %d%n", getPort());
     }
 
+    public void prepareForShutdown() {
+        // Stop any DH-started threads and work
+        ProcessEnvironment.getGlobalShutdownManager().maybeInvokeTasks();
+
+        // Shut down our wrapped stdout/stderr instances
+        System.out.close();
+        System.err.close();
+    }
+
     public int getPort() {
         return server.server().getPort();
     }