Multiple Java Apps in same JVM

Hi,
I have created a shell script which calls my java application with heap size as below:
/bin/java -Xms:3072M -Xmx:3072M ...
I'm calling the shell script multiple times in the background to create multiple instances of my java application in the same box. I have set a limit of 5 for java applications at any point of time. But what I'm experiencing is that first few sets of java application finish very fast (almost 3 mins) but last few sets taking a lot of time (around 10 mins). The quantity of data processed by all java applications is same but why later sets of java application is taking longer?
Can I do something here so that later sets of apps also completes in 3 mins? Can I refresh java heap before submitting another set of java applications? Java application is not mine but I have purchased from 3rd party. Please help!!!
Thanks in advance.

> why later sets of java application is taking longer?
Probably because of CPU usage. But could be memory.
>Can I do something here so that later sets of apps also completes in 3 mins
You tune the task, the complete task, to the box. That means you must understand in detail what is taking time and then architect that to make the best use of the available CPUs and memory (and other resources as used by the task.)

Similar Messages

How do I run multiple java apps in one JVM to reduce memory use?

Hi all,
I saw an article either on the web or in a magazine not too long ago about how to "detect" if the app is already running, and if so, it hands off the new instance to the already running JVM, which then creates a thread to run the Java app in. As it turns out, my app will be used in an ASP environment, through Citrix. We may have as many as 50 to 100 users running the same app, each with their own unique user ID, but all using the same one server to run it on. Each instance eats up 25MB of memory right now. So the question is if anybody knows of a URL or an app like this that can handle the process of running the same (or even different Java) apps in one JVM as separate threads, instead of requring several instances of the JVM to run? I know this article presented a fully working example, and I believe I know enough to do it but I wanted ot use the article as a reference to make sure it is done right. I know that each app basically would use the same one "launcher" program that would on first launch "listen" to a port, as well as send a message through the port to see if an existing launcher was running. If it does, it hands off the Java app to be run to the existing luancher application and shuts down the 2nd launching app. By using this method, the JVM eats up its normal memory, but each Java app only consumes its necessary memory as well and doesn't use up more JVM instance memory.
Thanks.

<pre>
import java.util.Properties;
import java.io.FileInputStream;
import java.io.IOException;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.util.Enumeration;
import java.util.NoSuchElementException;
public class RunProg implements Runnable, Cloneable
private String iProg;
private String iArgs[];
public static void main(String args[])
new RunProg().main();
// first step is to start main program itself
private void main()
Properties properties = System.getProperties();
try
properties.load(new FileInputStream("RunProg.properties"));
catch(IOException e)
System.setProperties(properties);
int i = 0;
System.out.println("enter main, activeCount=" + Thread.activeCount());
while(true)
String program = properties.getProperty("Prog" + i);
if(program == null)
break;
StringTokenizer st = new StringTokenizer(program);
String[] args = new String[st.countTokens() - 1];
try
RunProg rp = (RunProg)this.clone();
rp.iProg = st.nextToken();
for(int j = 0; st.hasMoreTokens(); j++)
     args[j] = st.nextToken();
rp.iArgs = args;
Thread th = new Thread(rp);
th.setName("prog" + i + "=" + program);
th.start();
System.out.println("prog" + i + "=" + program + ", started");
catch(CloneNotSupportedException e)
System.out.println("prog" + i + "=" + program + ", can't start");
i++;
     System.out.println("end of main, activeCount=" + Thread.activeCount());
// next step is to start all others one by one
public void run()
try
Class c = Class.forName(iProg);
Class p[] = new Class[1];
p[0] = String[].class;
Method m = c.getMethod("main", p);
Object o[] = new Object[1];
o[0] = iArgs;
m.invoke(null, o);
catch(ClassNotFoundException e)
System.out.println(iProg + "ClassNotFoundException");
catch(NoSuchMethodException e)
System.out.println(iProg + "NoSuchMethodException");
catch(InvocationTargetException e)
System.out.println(iProg + "NoSuchMethodException");
catch(IllegalAccessException e)
System.out.println(iProg + "NoSuchMethodException");
System.out.println(Thread.currentThread().getName() + ", ended");
System.out.println("exit run, activeCount=" + Thread.activeCount());
// setup SecurityManager to disable method System.exit()
public RunProg()
     SecurityManager sm = new mySecurityManager();
     System.setSecurityManager(sm);
// inner-class to disable method System.exit()
protected class mySecurityManager extends SecurityManager
     public void checkExit(int status)
          super.checkExit(status);
          Thread.currentThread().stop();
          throw new SecurityException();
* inner-class to analyze StringTokenizer. This class is enhanced to check double Quotation marks
protected class StringTokenizer implements Enumeration
private int currentPosition;
private int maxPosition;
private String str;
private String delimiters;
private boolean retTokens;
* Constructs a string tokenizer for the specified string. All
* characters in the <code>delim</code> argument are the delimiters
* for separating tokens.
* <p>
* If the <code>returnTokens</code> flag is <code>true</code>, then
* the delimiter characters are also returned as tokens. Each
* delimiter is returned as a string of length one. If the flag is
* <code>false</code>, the delimiter characters are skipped and only
* serve as separators between tokens.
* @param str a string to be parsed.
* @param delim the delimiters.
* @param returnTokens flag indicating whether to return the delimiters
* as tokens.
public StringTokenizer(String str, String delim, boolean returnTokens)
currentPosition = 0;
this.str = str;
maxPosition = str.length();
delimiters = delim;
retTokens = returnTokens;
* Constructs a string tokenizer for the specified string. The
* characters in the <code>delim</code> argument are the delimiters
* for separating tokens. Delimiter characters themselves will not
* be treated as tokens.
* @param str a string to be parsed.
* @param delim the delimiters.
public StringTokenizer(String str, String delim)
this(str, delim, false);
* Constructs a string tokenizer for the specified string. The
* tokenizer uses the default delimiter set, which is
* <code>"\t\n\r\f"</code>: the space character, the tab
* character, the newline character, the carriage-return character,
* and the form-feed character. Delimiter characters themselves will
* not be treated as tokens.
* @param str a string to be parsed.
public StringTokenizer(String str)
this(str, " \t\n\r\f", false);
* Skips delimiters.
protected void skipDelimiters()
while(!retTokens &&
(currentPosition < maxPosition) &&
(delimiters.indexOf(str.charAt(currentPosition)) >= 0))
currentPosition++;
* Tests if there are more tokens available from this tokenizer's string.
* If this method returns <tt>true</tt>, then a subsequent call to
* <tt>nextToken</tt> with no argument will successfully return a token.
* @return <code>true</code> if and only if there is at least one token
* in the string after the current position; <code>false</code>
* otherwise.
public boolean hasMoreTokens()
skipDelimiters();
return(currentPosition < maxPosition);
* Returns the next token from this string tokenizer.
* @return the next token from this string tokenizer.
* @exception NoSuchElementException if there are no more tokens in this
* tokenizer's string.
public String nextToken()
skipDelimiters();
if(currentPosition >= maxPosition)
throw new NoSuchElementException();
int start = currentPosition;
boolean inQuotation = false;
while((currentPosition < maxPosition) &&
(delimiters.indexOf(str.charAt(currentPosition)) < 0 || inQuotation))
if(str.charAt(currentPosition) == '"')
inQuotation = !inQuotation;
currentPosition++;
if(retTokens && (start == currentPosition) &&
(delimiters.indexOf(str.charAt(currentPosition)) >= 0))
currentPosition++;
String s = str.substring(start, currentPosition);
if(s.charAt(0) == '"')
s = s.substring(1);
if(s.charAt(s.length() - 1) == '"')
s = s.substring(0, s.length() - 1);
return s;
* Returns the next token in this string tokenizer's string. First,
* the set of characters considered to be delimiters by this
* <tt>StringTokenizer</tt> object is changed to be the characters in
* the string <tt>delim</tt>. Then the next token in the string
* after the current position is returned. The current position is
* advanced beyond the recognized token. The new delimiter set
* remains the default after this call.
* @param delim the new delimiters.
* @return the next token, after switching to the new delimiter set.
* @exception NoSuchElementException if there are no more tokens in this
* tokenizer's string.
public String nextToken(String delim)
delimiters = delim;
return nextToken();
* Returns the same value as the <code>hasMoreTokens</code>
* method. It exists so that this class can implement the
* <code>Enumeration</code> interface.
* @return <code>true</code> if there are more tokens;
* <code>false</code> otherwise.
* @see java.util.Enumeration
* @see java.util.StringTokenizer#hasMoreTokens()
public boolean hasMoreElements()
return hasMoreTokens();
* Returns the same value as the <code>nextToken</code> method,
* except that its declared return value is <code>Object</code> rather than
* <code>String</code>. It exists so that this class can implement the
* <code>Enumeration</code> interface.
* @return the next token in the string.
* @exception NoSuchElementException if there are no more tokens in this
* tokenizer's string.
* @see java.util.Enumeration
* @see java.util.StringTokenizer#nextToken()
public Object nextElement()
return nextToken();
* Calculates the number of times that this tokenizer's
* <code>nextToken</code> method can be called before it generates an
* exception. The current position is not advanced.
* @return the number of tokens remaining in the string using the current
* delimiter set.
* @see java.util.StringTokenizer#nextToken()
public int countTokens()
int count = 0;
int currpos = currentPosition;
while(currpos < maxPosition)
* This is just skipDelimiters(); but it does not affect
* currentPosition.
while(!retTokens &&
(currpos < maxPosition) &&
(delimiters.indexOf(str.charAt(currpos)) >= 0))
currpos++;
if(currpos >= maxPosition)
break;
int start = currpos;
boolean inQuotation = false;
while((currpos < maxPosition) &&
(delimiters.indexOf(str.charAt(currpos)) < 0 || inQuotation))
if(str.charAt(currpos) == '"')
inQuotation = !inQuotation;
currpos++;
if(retTokens && (start == currpos) &&
(delimiters.indexOf(str.charAt(currpos)) >= 0))
currpos++;
count++;
return count;
</pre>
RunProg.properties like this:
Prog1=GetEnv 47838 837489 892374 839274
Prog0=GetEnv "djkfds dfkljsd" dsklfj

Running multiple java-apps in single JVM?

We have about 125 Citrix clients running on 5 Citrix Servers. We are investigating a new very big development project which will cover about 10 main projects with 15 Applications each. The complete project will be written in Java.
Basically, each module will have it's own JVM. BUt, when each client runs a couple of modules, the servers will surely run out of memory...
I searched for way's to run different modules within 1 single JVM but it seems to be 'not done', because of 'System.exit()', 'Static Variable' probs to name only 2.
Any idea's on how to implement this?
thanks.

thanks for the reply.
Yes, I assume the server will run out of memory.
1) Our citrix servers are consuming about 3/4th of their 4Gb memory capacity without any java_application running.
2) Each of our 5 Citrix servers has 25 users active
3) Each JVM takes about 20mb memory
4) Each user will run at least 3 app's simultaneously
Abouve results in 3*20=60Mb / user * 25= 1,5Gb memory extra needed.
Can you give me an example of a Thread.sleep(60000) test_pgm?
and/or an example for a "classloader" program to launch each app in its ow sandbox (in same JVM)?
(eventually a link to get more info on this)
thanks

Multiple web apps sharing same cache in a single JVM ?

Is it possible to share cache across multiple web apps running in the same app server (multiple web apps, single JVM) ?
Thanks for any info.

Hi Bob,
Cluster membership is scoped to the ClassLoader, so if your application server provides a ClassLoader-per-application, this will work fine.
This is supported for both Coherence (NamedCaches) and Coherence*Web (HTTP sessions).
Jon Purdy
Tangosol, Inc.

Run two java apps in separate jvm's on the same machine?

At the command line, when you type:
java MyClass
and then type:
java MyClass
are the two programs (assuming neither terminated prior to the other's execution) is it running in a separate Java Virtual Machine or the same one?
And if they're running in the same JVM, is there a way to run the second program in a separate JVM for testing purposes even though they're on the same computer? (btw I'm running windows XP).

thanks all...just a quick follow up question. Are two
separate jvm's on the same computer a good
representation of two jvms running on separate
computers?Don't know what you mean by "a good representation."
They're two separate processes. For basic testing, not worrying about performance, etc., and if your code doesn't do anything special to treat two VMs on the same box differently than two VMs on separate boxes, it's probably a reasonable approximation.

Multiple Java apps running in one VM

I have one VM that runs one application with GUI, database. It also spawns another VM to run more apps through Sockets.
Is there a way to run several Java apps within a single VM? If so, I can get rid of those interprocess communication stuff and make things easier.
Thanks in advance.
Lee

Yes you can do what to want to do. It is actually very benificail. Take a look at this article:
http://java.sun.com/docs/books/performance/1st_edition/html/JPClassLoading.fm.html#24732
here is code to do it as well:
package com.ist.system;
import com.ist.util.LogMsg;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.Method;
import java.net.InetAddress;
import java.net.Socket;
* This class was pulled from:
* http://java.sun.com/docs/books/performance/1st_edition/html/JPClassLoading.fm.html#24732
* It was written to provide the ability to launch many applications in the
* same JVM. By doing this, it will save on system resources like RAM. When
* the <code>launch</code> method is called, it will check to see if there is a
* VM already running. If there is, it will launch the new application in the
* currently running VM. If there isn't, it will create a process that will
* keep a VM alive until there are no more applications running. Once there are
* no more applications running, this service will System.exit.
public class Launcher {
    static final int socketPort = 9876;
     * This method will launch a new instance of the passed in className
     * in an already running JVM if one is already running. If one is not
     * running, this application will create one.
     * @param className the class which you wish to launch
    public void launch(String className) {
        LogMsg.shortDebug("Trying to launch: " + className);
        Socket s = findService();
        if (s != null) {
            LogMsg.shortDebug("Launcher found service");
            try {
                OutputStream oStream = s.getOutputStream();
                byte[] bytes = className.getBytes();
                oStream.write(bytes.length);
                oStream.write(bytes);
                oStream.close();
                LogMsg.shortDebug(className);
            } catch (IOException e) {
                LogMsg.warn("Launcher couldn't talk to service");
        } else {
            LogMsg.event("Starting new service");
            Launcher.go(className);
            Thread listener = new ListenerThread();
            listener.start();
            LogMsg.shortDebug("Started service listener");
    protected Socket findService() {
        try {
            Socket s = new Socket(InetAddress.getLocalHost(),
            socketPort);
            return s;
        } catch (IOException e) {
            // couldn't find a service provider
            return null;
    public static synchronized void go(final String className) {
        LogMsg.shortDebug("Launcher running a " + className);
        Thread thread = new Thread() {
            public void run() {
                try {
                    Class clazz = Class.forName(className);
                    Class[] argsTypes = {String[].class};
                    Object[] args = {new String[0]};
                    Method method = clazz.getMethod("main", argsTypes);
                    method.invoke(clazz, args);
                } catch (Exception e) {
                    LogMsg.shortDebug("Launcher coudn't run the " + className);
        }; // end thread sub-class
        thread.start();
        runningPrograms++;
    static int runningPrograms = 0;
     * All programs wishing to exit should call this method and NOT
     * use System.exit. Calling System.exit will kill all the applications
     * running in this VM.
    public static synchronized void programQuit() {
        runningPrograms--;
        if (runningPrograms <= 0) {
            System.exit(0);
    public static void main(String[] args) {
        LogMsg.setupTraceLevel();
        Launcher l = new Launcher();
        l.launch(args[0]);
}

Connect Multiple Ingrian server in same JVM

Hi All,
I have faced an issue where I have to connect multiple Ingrain server depending on some choice in same JVM.However I can able to set one server for jvm by placing the IngrianNAE.jar and IngrianNAE.properties in jre/lib/ext and every things running well, but if I tried to modify the Ingrain properties file during runtime through System.setProperties(), it always pick the old value instead the new one. So my question is that whether it is possible to configure for same JVM or not.
Thanks & Regards

Any Inputs...?

Running multiple java apps simultaneously, each using a different jre.

I have a situation where I have 3 or 4 applications (and one applet) that were built over time, each with a different version of the jdk (ranging from 1.2.2.005 to 1.3.2). I need to know of a way (and it must exist) to run each of these applications on the same machine, and at runtime, have each application (or applet) run with its respective version of the jre. Certainly, one could change some source code and make all programs compatible with a particular jre, but that doesn't solve my problem if a new app is built with a new version of the jdk down the road. Currently, each runs fine by themselves, but if I try to run them together as different processes, some won't do anything because the default jre may not be what it needs. Would the Java Plug-in software have a role to play in this? Is there a way to specify (link) which application should use which jre?
P.S. These applications (right now) don't have to interact or interface in any way. I just need to have them all running as separate processes on the same machine and be able to jump from one to the other.

However ... if you have the programs running in Java1.x, I
wouldn't recommend to let it run under Java 1.y; atleast
not without thorough testing.I do it all the time and have not had a problem. I'm
currently using JDK 1.4 beta 3 and I regularly run a
Java application written with JDK 1.1.
It sounds like the programs you are running are
relying on behavior that is not guaranteed. If that
behavior changes in a later version, it can break your
program. Program to the contracts provided by other
classes and packages, and you should have few or no
problems.I guess you are right. Maybe you can help me with the following problem (this is off this topic, I know): I have Swing JDK 1.2 and Swing from JDK 1.3. I have to register keys on components.
In JDK 1.2 I can use registerKeyBoardAction, in JDK 1.3 I have to use input maps and action maps. Both solutions only work with certain JDK. What I did was writing code which detects the java version and takes the appropriate action to register the keys. To make the thing compile in 1.2, I have to use reflection for the input/action map methods, because they are only available in 1.3.
Any idea how to solve this more elegantly ?

Running multiple java apps simultaneously, using different versions of jre.

I have a situation where I have 3 or 4 applications (and one applet) that were built over time, each with a different version of the jdk (ranging from 1.2.2.005 to 1.3.2). I need to know of a way (and it must exist) to run each of these applications on the same machine, and at runtime, have each application (or applet) run with its respective version of the jre. Certainly, one could change some source code and make all programs compatible with a particular jre, but that doesn't solve my problem if a new app is built with a new version of the jdk down the road. Currently, each runs fine by themselves, but if I try to run them together as different processes, some won't do anything because the default jre may not be what it needs. Would the Java Plug-in software have a role to play in this? Is there a way to specify (link) which application should use which jre?
P.S. These applications (right now) don't have to interact or interface in any way. I just need to have them all running as separate processes on the same machine and be able to jump from one to the other.

Write a batch file that sets the environment properly and restores it afterwards, here is a sample batch file we use which switches to IBM's JRE to run an app:
OLDPATH=$PATH
PATH=$PATH:"/usr/local/java/IBMJava2-13/jre/bin"
OLDCP=$CLASSPATH
CLASSPATH="/usr/local/java/IBMJava2-13/jre/lib/rt.jar:."
OLDHOME=$JAVA_HOME
JAVA_HOME="/usr/local/java/IBMJava2-13/jre"
# put the command to execute your program here
java -jar app.jar
PATH=$OLDPATH
CLASSPATH=$CLASSPATH
JAVA_HOME=$JAVA_HOME
This is for Linux, but it should be possible to write one for Windows too.

Multiple java threads in a JVM created by the invocation interface

Hi,
I have a certain application APP that calls functions of a C library. One of these functions creates a JVM through the invocation interface. In the JVM I create some other threads and a Swing GUI. From the java "main" thread as well as the other threads (including the Swing event dispatcher thread) I need to call dll functions through native java methods. The latter indirectly (through another dll) invoke functions of an API of application APP.
I have problems when making calls from the java threads to the java native library. In some cases everything works well i.e., I'm able to make calls to the java native library from both the "main" java thread and the other threads. In other cases a crash occurs when attempting to access the native library from any threads but the "main" thread.
Can anyone help me on this? Is there any requirement that only the main java thread makes callbacks to C code?
Thanks.

> why later sets of java application is taking longer?
Probably because of CPU usage. But could be memory.
>Can I do something here so that later sets of apps also completes in 3 mins
You tune the task, the complete task, to the box. That means you must understand in detail what is taking time and then architect that to make the best use of the available CPUs and memory (and other resources as used by the task.)

Running 2 java apps means 2 JVM instances ?

For each running Java application I start on my desktop do I get a seperate instance of the JVM ? If so that seems like such a waste ...

Yes. If you find this wasteful, though, you could write a Java application that runs your applications in a single JVM, in separate threads, but that would be violating the first two rules of optimization:
1. Don't do it.
2. Don't do it yet.
Those rules are there to remind you not to try to optimize a situation until you know that it needs to be optimized and until you know how to optimize it.

Mixing multiple rmi protocols in same jvm

We are having to build a gateway between Javelin's Coppelia server and
WLAS 6.0. Coppelia has its own rmi implementation and WLAS has its T3
protocol. Is it possible to mix connections between both of them in one
jvm. It would seem ok and we are tying to test it now but wanted to get
confirm from BEA folks.

"Larry Presswood" <[email protected]> wrote in message
news:[email protected]..
We are having to build a gateway between Javelin's Coppelia server and
WLAS 6.0. Coppelia has its own rmi implementation and WLAS has its T3
protocol. Is it possible to mix connections between both of them in one
jvm. It would seem ok and we are tying to test it now but wanted to get
confirm from BEA folks.Larry,
We've not tested this configuration. However I can't think of anything off
hand that would prevent it from working. Let me know how it goes, I'd be
happy to try to help if something comes up.
Good luck!
Adam

Show java app name in task manager

Right now if I run 10 java apps in seperate JVMs, it shows 10 copies of java.exe in the task manager on Windows NT/2000.
Does anyone know a way to change the image name when I launch my java apps, or a simple way to create a java "application" for windows (for example, NetBeans shows up as Netbeans.exe even though it is a java app).
Thanks!

Turns out you can copy java.exe to anyname.exe and execute anyname.exe just like java.exe.
DOH!

Launch multiple WS apps from a local Java application?

I should develop a local Java application that on demand launches webstart applications. Obviously it could be done with a simple HTML file, but the requirements are that launched apps be monitored by the launching app, so they need to be in the same JVM.
I tried
java -Djnlpx.home="C:/programfilesdir/Java Web Start"
-classpath ".;..\classes;..\lib;..\lib\javaws.jar" Launcher
Then Launcher.java calls com.sun.javaws.Main's main method passing the JNLP URL as a parameter.
This launches Java Web Start and then the child app, but for some reason I ignore the Launcher app is exited without exceptions as soon as javaws starts.
Provided that the Java WS app manager is itself a Java app that launches WS app's, any clue on how to do the same thing? Or can the source code be inspected?
Thanks.

I should develop a local Java application that on
demand launches webstart applications. Obviously it
could be done with a simple HTML file, but the
requirements are that launched apps be monitored by
the launching app, so they need to be in the same
JVM.You might check out netx, a open-source JNLP client that has extra support for running multiple apps in a single JVM. It includes a SecurityManager that can catch System.exit and close the calling app's windows and resources (applet sounds, etc) instead of closing the JVM. It has other support too like separate look and feels for each app.
It doesn't yet implement all of the spec though, but it does run most JNLP apps.
http://jnlp.sourceforge.net/netx/

Same JVM for multiple Frames in a web application

Hi guys,
I have a web application that loads an applet during login. Once the login is completed, the web application will display the available functions accessible with a menu on the left frame and the main display page on the right frame. Whenever any form action is perfomed on the right frame, the jvm with the login session seems to exit (java console closes) and the applet will be loaded to prompt the user to login again. The JRE installed on the Windows client is 1.6.0_14 from SUN.
I'm guessing that the different frames are using different JVMs?
Is there a way to use the same jvm for a web application with multiple frames? I want to prevent the case where the user will have to login again.
Thanks for any advice!
- Zen -

I have sort of the same problem
[Identical applets in the same JVM, next generation plugin issue|http://forums.sun.com/thread.jspa?threadID=5396118]
I have submitted a Request for enhancement to SUN to allow forced grouping of applets in the same JVM.
Sort of the opposite of the "separate_jvm" Applet tag parameter.
It seems there is currently no way to do this.
[New Plugin command line args|https://jdk6.dev.java.net/plugin2/jnlp/#COMMAND_LINE_ARGS]
When per-applet JVM command-line arguments are specified, it is likely that the new Java Plug-In will need to launch another JVM instance in order to satisfy them. In other words, it is unlikely that a preexisting JVM instance will have been started with the correct set of command-line arguments to satisfy the current applet's request. The rules for exactly when a new JVM instance is launched to start a given applet are deliberately left unspecified, as this functionality is brand new in the 6u10 release and may need to change in subsequent releases. Here is a rough set of guidelines for the sharing and creation of new JVM instances:
* If the command-line arguments used to start a preexisting JVM instance are a superset of the requested arguments, the preexisting JVM instance will be used.
* If a JVM instance is launched for the "default" set of command-line arguments (i.e., those specified in the Java Control Panel, with no per-applet arguments specified), then this JVM instance will never be used to launch any applet that has even one per-applet command-line argument.
* -Xmx is handled specially: if a preexisting JVM instance was started with for example -Xmx256m, and a new applet requests -Xmx128m, then new applet will very likely be run in the preexisting JVM instance. In other words, -Xmx specifications are matched with a greater-than-or-equal test.
There is no way to "name" a JVM instance used to launch a particular applet and "force" subsequent applets into that JVM instance.
See the section on the separate_jvm parameter to isolate a particular applet in its own JVM instance, separate from all other applets.

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