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POUsing Spring threading and TaskExecutor, how do I know when a thread is finished?
 

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  1. POUsing Spring threading and TaskExecutor, how do I know when a thread is finished?
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    <p>Alright, possible a naive question here. I have a service that needs to log into multiple network devices, run a command on each and collect the results. For speed, rather than collect the information on each device in sequence, I need to access them all concurrently and consume the results after they are done. </p> <p>Using the Spring framework and Jsch I'm quite easily able to query each device correctly. Where I am running into some confusion is in trying to rewire the beans to use TaskExecutor to accomplish this. What I can't figure out how to do is how to know when the thread is finished.</p> <p>What I have so far is this:</p> <pre><code>public class RemoteCommand { private String user; private String host; private String password; private String command; private List&lt;String&gt; commandResults; private TaskExecutor taskExecutor; public RemoteCommand(String user, String host, String password, TaskExecutor taskExecutor) { setUser(user); setHost(host); setPassword(password); setTaskExecutor(taskExecutor); } /** * @param user the user to set */ public void setUser(String user) { this.user = user; } /** * @return the user */ public String getUser() { return user; } /** * @param host the host to set */ public void setHost(String host) { this.host = host; } /** * @return the host */ public String getHost() { return host; } /** * @param password the password to set */ public void setPassword(String password) { this.password = password; } /** * @return the password */ public String getPassword() { return password; } /** * @param command the command to set */ private void setCommand(String command) { this.command = command; } /** * @return the command */ private String getCommand() { return command; } /** * @param commandResults the commandResults to set */ private void setCommandResults(List&lt;String&gt; commandResults) { this.commandResults = commandResults; } /** * @return the commandResults */ public List&lt;String&gt; getCommandResults(String command) { taskExecutor.execute(new CommandTask(command) ); return commandResults; } /** * @param taskExecutor the taskExecutor to set */ public void setTaskExecutor(TaskExecutor taskExecutor) { this.taskExecutor = taskExecutor; } /** * @return the taskExecutor */ public TaskExecutor getTaskExecutor() { return taskExecutor; } private class CommandTask implements Runnable { public CommandTask(String command) { setCommand(command); System.out.println("test: " + getCommand()); } /** * * @param command */ public void run() { List&lt;String&gt; results = new LinkedList&lt;String&gt;(); String command = getCommand(); try { System.out.println("running"); JSch jsch = new JSch(); String user = getUser(); String host = getHost(); java.util.Properties config = new java.util.Properties(); config.put("StrictHostKeyChecking", "no"); host = host.substring(host.indexOf('@') + 1); Session session = jsch.getSession(user, host, 22); session.setPassword(getPassword()); session.setConfig(config); session.connect(); Channel channel = session.openChannel("exec"); ((ChannelExec) channel).setCommand(command); channel.setInputStream(null); ((ChannelExec) channel).setErrStream(System.err); InputStream in = channel.getInputStream(); channel.connect(); byte[] tmp = new byte[1024]; while (true) { while (in.available() &gt; 0) { int i = in.read(tmp, 0, 1024); if (i &lt; 0) break; results.add(new String(tmp, 0, i)); System.out.print(new String(tmp, 0, i)); } if (channel.isClosed()) { //System.out.println("exit-status: " // + channel.getExitStatus()); break; } try { Thread.sleep(1000); } catch (Exception ee) { ee.printStackTrace(); } } channel.disconnect(); session.disconnect(); } catch (Exception e) { System.out.println(e); } setCommandResults(results); System.out.println("finished running"); } } } </code></pre> <p>Within my junit test I have:</p> <pre><code>@Test public void testRemoteExecution() { remoteCommand = (RemoteCommand) applicationContext.getBean("remoteCommand"); remoteCommand.getCommandResults("scripts/something.pl xxx.xxx.xxx.xxx"); //List&lt;String&gt; results = remoteCommand.getCommandResults("scripts/something.pl xxx.xxx.xxx.xxx"); //for (String line : results) { // System.out.println(line.trim()); //} } </code></pre> <p>My applicationContext.xml file:</p> <pre><code> &lt;bean id="taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor"&gt; &lt;property name="corePoolSize" value="5" /&gt; &lt;property name="maxPoolSize" value="10" /&gt; &lt;property name="queueCapacity" value="25" /&gt; &lt;/bean&gt; &lt;!-- ******************** --&gt; &lt;!-- Utilities --&gt; &lt;!-- ******************** --&gt; &lt;bean name="remoteCommand" class="com.xxx.ncc.sonet.utilities.RemoteCommand" scope="prototype"&gt; &lt;description&gt;Remote Command&lt;/description&gt; &lt;constructor-arg&gt;&lt;value&gt;${remote.user}&lt;/value&gt;&lt;/constructor-arg&gt; &lt;constructor-arg&gt;&lt;value&gt;${remote.host}&lt;/value&gt;&lt;/constructor-arg&gt; &lt;constructor-arg&gt;&lt;value&gt;${remote.password}&lt;/value&gt;&lt;/constructor-arg&gt; &lt;constructor-arg ref="taskExecutor" /&gt; &lt;/bean&gt; </code></pre> <p>I get as far as the first println in the run() method. Then the test exits cleanly with no errors. I never get to the second println at the bottom of that routine. I've looked at this thread <a href="https://stackoverflow.com/questions/702415/how-to-know-if-other-threads-have-finished">here</a>, which was very useful, but not implemented in a Spring specific fashion. I'm sure I'm missing something simple, or have completely run off the rails here. Any help is appreciated.</p>
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