如何从另一个线程强制关闭JDBC连接？

Question

I have two threads in java application. The first thread runs the JDBC connection logic. The second one is listening to user's command.

    public static void main ... 

    private Connection c; // this is JDBC connection visible to both Thread 1 and 2

    Thread thread1 = new Thread(new Runnable() {
            public void run() {  
    // logic to execute SQL statements on Connection c 
    }
    ); 

    Thread thread2 = new Thread(new Runnable() {
            public void run() { 
      // Here i try to execute connection close on user's demand. 
      c.close(); 
      // this command executes with no error, 
      // but the connection doesnt close immediately. 
      // The SQL statements in thread 1 somehow waits to finish, 
      // and only then will the connection stop. 
      // How to forcefully and abruptly stop the connection ? 
    } 
); 

How to forcefully and abruptly stop the connection ?

Answer 1

You could try calling c.close() in the 2nd thread, but:

• JDBC connection objects are not thread-safe ¹ , so the Java-side behavior is unspecified.

• AFAIK, the JDBC spec doesn't say what will happen on the database server if a database connection is closed while a request is in progress. It is not clear if the request is terminated immediately or a bit later (with a transaction rollback or not).

So my advice would be don't do this. Find another way to do what you are trying to do.

(If you want advice on other ways, tell us the real problem you are trying to solve here rather than your roadblock with your attempted solution to the problem.)

---

^{1 - More precisely, they are not required to be thread-safe by the JDBC spec. They might actually be (sufficiently) thread-safe in some driver implementations, but ... only if the vendor docs say so. From various sources, at least Oracle DB and Derby support multiple threads sharing a logical JDBC connection, though they seem to support different models.}

Answer 2

I don't think you can this way. But you can exit the whole JVM forcely:)