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.
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.
What I have so far is this:
public class RemoteCommand {
private String user;
private String host;
private String password;
private String command;
private List<String> 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<String> commandResults) {
this.commandResults = commandResults;
}
/**
* @return the commandResults
*/
public List<String> 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<String> results = new LinkedList<String>();
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() > 0) {
int i = in.read(tmp, 0, 1024);
if (i < 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");
}
}
}
Within my junit test I have:
@Test
public void testRemoteExecution() {
remoteCommand = (RemoteCommand) applicationContext.getBean("remoteCommand");
remoteCommand.getCommandResults("scripts/something.pl xxx.xxx.xxx.xxx");
//List<String> results = remoteCommand.getCommandResults("scripts/something.pl xxx.xxx.xxx.xxx");
//for (String line : results) {
// System.out.println(line.trim());
//}
}
My applicationContext.xml file:
<bean id="taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
<property name="corePoolSize" value="5" />
<property name="maxPoolSize" value="10" />
<property name="queueCapacity" value="25" />
</bean>
<!-- ******************** -->
<!-- Utilities -->
<!-- ******************** -->
<bean name="remoteCommand" class="com.xxx.ncc.sonet.utilities.RemoteCommand" scope="prototype">
<description>Remote Command</description>
<constructor-arg><value>${remote.user}</value></constructor-arg>
<constructor-arg><value>${remote.host}</value></constructor-arg>
<constructor-arg><value>${remote.password}</value></constructor-arg>
<constructor-arg ref="taskExecutor" />
</bean>
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 here, 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.
1 Answer