#78: Added shutdown() method to DefaultEnv to stop thread pools and updated Integration Guide and FAQ.

Author: jaccomoc

docs/pages/faq.md

@@ -160,7 +160,7 @@ blank lines (or 33K including comments and blank lines).
 
 ### How many test cases are there?
 
-There are currently over 11K individual test cases.
+There are currently over 11,000 individual test cases.
 Each test case is a Jactl script that is compiled, run, and then verified against the expected
 result (or the expected error).
 
@@ -213,6 +213,18 @@ def decoded = x.base64Decode()    // will be array of bytes: [1, 2, 3, 4]
 ```
 See the [Integration Guide](integration-guide.md) for more information.
 
+### Why doesn't my Java program exit after evaluating a Jactl script?
+
+If you have a simple Java program where you evaluate a Jactl script using the default execution
+environment, there will be some daemon threads that have been started in the background and
+if you don't stop these threads, the JVM will not normally exit (unless `System.exit()` is called).
+
+Note that these threads are shared and only started up once.
+
+You can use the static method `io.jactl.DefaultEnv.shutdown()` to stop these threads.
+
+See [Integration Guide](integration-guide.md) for more information.
+
 ### Is there an IntelliJ plugin for Jactl?
 
 Yes, there is an IntelliJ plugin.

docs/pages/integration-guide.md

@@ -187,6 +187,29 @@ All these exception classes are subclasses of the top level `io.jactl.JactlError
 > **Note**<br/>
 > All of these classes are unchecked exceptions so be sure to catch them at the appropriate place in your code.
 
+### Default Execution Environment and Shutdown
+
+By default, if you have not provided an implementation of the `JactlEnv` interface
+(see [Jactl Execution Environment](#jactl-execution-environment) below) you will be using the
+built-in `io.jactl.DefaultEnv`.
+
+This class creates static thread pools for the non-blocking event loop threads, the blocking
+threads, and a thread for timers.
+
+Since these thread-pools are daemon threads, if you want to cleanly exit without invoking
+`System.exit()`, you will need stop these thread-pools using the static `io.jactl.DefaultEnv.shutdown()`
+method:
+
+```java
+class MyTest {
+  public static void main(String[] args) {
+    Object result = Jactl.eval("3 + 5");
+    System.out.println("Result is " + result);
+    io.jactl.DefaultEnv.shutdown();
+  }
+}
+```
+
 ## JactlContext
 
 Although most of the examples shown so far haven't used a JactlContext, in general, you will need to create an object

src/main/java/io/jactl/DefaultEnv.java

@@ -65,4 +65,10 @@ public void scheduleBlocking(Runnable blocking) {
   public Object getThreadContext() {
     return null;
   }
+
+  public static void shutdown() {
+    eventLoop.shutdown();
+    blockingExecutor.shutdown();
+    timerService.shutdown();
+  }
 }