InitialDirContext Throwing ServiceUnavailableException socket closed

Question

Any assistance is appreciated.
Problems occurring when multiple DirContext instances are created. Attempting to make a SSL connection to Active Directory on port 636. A single successful context can be established in the below code. However, a second instantiation of InitialDirContext(env) results in a javax.naming.ServiceUnavailableException: [domain]:636; socket closed error. Multiple contexts are desired to establish a connection pool.
A few items to note. Establishing four unsecure DirContext on port 389 works successfully. I can establish a DirContext on port 636, use the context, close the context then establish new contexts without a problem. A server certificate was imported to the C:\j2sdk1.4.2_11\jre\lib\security\cacerts file. Testing on a local computer. Below is sample code:
public static void main(String[] args) {
    try {
        System.setProperty("javax.net.debug","all");
        // Set up the environment for creating the initial context
        Hashtable env = new Hashtable();
         env.put(Context.INITIAL_CONTEXT_FACTORY,"com.sun.jndi.ldap.LdapCtxFactory");
        env.put(Context.SECURITY_PRINCIPAL, "[USER DN]");
        env.put(Context.SECURITY_CREDENTIALS, "[PWD]");
        //NON SSL
        //env.put(Context.PROVIDER_URL, "ldap://[server]:389");
        //SSL
        env.put(Context.PROVIDER_URL, "ldap://[server]:636");
        env.put(Context.SECURITY_PROTOCOL, "ssl");
        env.put(Context.SECURITY_AUTHENTICATION, "simple");
        // Create the initial context
        DirContext ctx = null;
        DirContext ctx2 = null;
        DirContext ctx3 = null;
        DirContext ctx4 = null;
        try {
            //Works every time...
            ctx = new InitialDirContext(env);
        } catch (NamingException e) {
            e.printStackTrace();
        try {
        //Fails on port 636, works on port 389
        ctx2 = new InitialDirContext(env);
        } catch (NamingException e) {
            e.printStackTrace(); 
        try {
        //Works on port 636 (after 2nd attempt fails) and port 389
        ctx3 = new InitialDirContext(env);
        } catch (NamingException e) {
            e.printStackTrace();
        try {
        //Fails on port 636, works on port 389
        ctx4 = new InitialDirContext(env);
        } catch (NamingException e) {
            e.printStackTrace();
        Attributes attrs = ctx.getAttributes("[A USER DN]");
        System.out.println("Total attributes returned: " + attrs.size());
        try {
            ctx.close();
            ctx2.close();
            ctx3.close();
            ctx4.close();
        } catch (NamingException e) {
            e.printStackTrace();
    } catch (Exception ex) {
        ex.printStackTrace();
    System.exit(0);
}The java debug statements at the second exception:
Thread-1, WRITE: TLSv1 Handshake, length = 121
Thread-1, received EOFException: ignored
Thread-1, called closeInternal(false)
Thread-1, SEND TLSv1 ALERT:  warning, description = close_notify
Plaintext before ENCRYPTION:  len = 18
0000: 01 00 0F 78 84 EE 16 24   F6 99 B0 83 52 14 FF 86  ...x...$....R...
0010: 29 3C                                              )<
Thread-1, WRITE: TLSv1 Alert, length = 18
Thread-1, called close()
Thread-1, called closeInternal(true)Again, any assistance is appreciated.

Answer 1

Multiple contexts are desired to establish a connection pool.The JNDI LDAP provider already does connection pooling so you don't need multiple initial contexts at all.