Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Here's some code showing the Future implementation and the Thread.stop() one. This is an interesting problem, and it points out the need for a hook in a ScriptEngine to be able to halt whatever script it's running for whatever reason. I wonder whether this would break the assumptions in most implementations since they assume <code>eval()</code> will be executed in a single-threaded (blocking) environment?</p> <p>Anyway, the results of executing the code below:</p> <pre><code>// exec with Thread.stop() $ java ExecJavascript Java: Starting thread... JS: Before infinite loop... Java: ...thread started Java: Thread alive after timeout, stopping... Java: ...thread stopped (program exits) // exec with Future.cancel() $ java ExecJavascript 1 Java: Submitting script eval to thread pool... Java: ...submitted. JS: Before infinite loop... Java: Timeout! trying to future.cancel()... Java: ...future.cancel() executed (program hangs) </code></pre> <p>Here's the full program:</p> <pre><code>import java.util.concurrent.*; import javax.script.*; public class ExecJavascript { private static final int TIMEOUT_SEC = 5; public static void main( final String ... args ) throws Exception { final ScriptEngine engine = new ScriptEngineManager() .getEngineByName("JavaScript"); final String script = "var out = java.lang.System.out;\n" + "out.println( 'JS: Before infinite loop...' );\n" + "while( true ) {}\n" + "out.println( 'JS: After infinite loop...' );\n"; if ( args.length == 0 ) { execWithThread( engine, script ); } else { execWithFuture( engine, script ); } } private static void execWithThread( final ScriptEngine engine, final String script ) { final Runnable r = new Runnable() { public void run() { try { engine.eval( script ); } catch ( ScriptException e ) { System.out.println( "Java: Caught exception from eval(): " + e.getMessage() ); } } }; System.out.println( "Java: Starting thread..." ); final Thread t = new Thread( r ); t.start(); System.out.println( "Java: ...thread started" ); try { Thread.currentThread().sleep( TIMEOUT_SEC * 1000 ); if ( t.isAlive() ) { System.out.println( "Java: Thread alive after timeout, stopping..." ); t.stop(); System.out.println( "Java: ...thread stopped" ); } else { System.out.println( "Java: Thread not alive after timeout." ); } } catch ( InterruptedException e ) { System.out.println( "Interrupted while waiting for timeout to elapse." ); } } private static void execWithFuture( final ScriptEngine engine, final String script ) throws Exception { final Callable&lt;Object&gt; c = new Callable&lt;Object&gt;() { public Object call() throws Exception { return engine.eval( script ); } }; System.out.println( "Java: Submitting script eval to thread pool..." ); final Future&lt;Object&gt; f = Executors.newCachedThreadPool().submit( c ); System.out.println( "Java: ...submitted." ); try { final Object result = f.get( TIMEOUT_SEC, TimeUnit.SECONDS ); } catch ( InterruptedException e ) { System.out.println( "Java: Interrupted while waiting for script..." ); } catch ( ExecutionException e ) { System.out.println( "Java: Script threw exception: " + e.getMessage() ); } catch ( TimeoutException e ) { System.out.println( "Java: Timeout! trying to future.cancel()..." ); f.cancel( true ); System.out.println( "Java: ...future.cancel() executed" ); } } } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POjava scripting API - how to stop the evaluation
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USChris Winters
    1. USChris Winters
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThis resumes control after 15 seconds with a timeout exception, but leaves the background thread running, so the question of how to interrupt it remains.
      singulars
      1. PO
      1. USAlexander Torstling
    2. CODuh! Thanks for the comment, added the Future cancellation.
      singulars
      1. PO
      1. USChris Winters
    3. COhi, thanks for the elegant solution, but even after the Future cancellation the background thread is still running consuming the CPU resources. so the question still remains..
      singulars
      1. PO
      1. USspecial0ne
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload