JDK21 introduces a bunch of useful functionalities around thread management such as virtual thread but it also changes things with regards to thread.stop functionality which affects ColdFusion’s implementation for thread’s functionality around termination.

First up, let’s understand what’s changing in thread terminate.

Why is cfthread.stop handling required?

The next release of ColdFusion upgrades Java to JDK21. JDK21 has removed the thread stop method so to certify it we will have to make changes in cfthread terminate and threadterminate which internally calls Java’s thread.stop.

Why has Java removed thread.stop?

The stop() method was considered unsafe. If a thread was stopped externally, all the monitors that the thread held became unlocked instantaneously. This could leave shared resources and variables in an unsafe, and unstable meta state.

Solution to absorb this change

Remove methods for ThreadTerminate cfthread attribute for terminating a thread.  Introduce a separate method for ThreadInterrupt and attribute for interrupting a thread.

ColdFusion currently exposes the ThreadTerminate method which stops a thread immediately. Internally we use Java’s Thread Stop which is being removed in JDK21 which is being removed so we will have to remove this method too.

Instead, users will be given the option to interrupt a thread using a new method called Thread interrupt method. This method is safer and a more graceful way of stopping a thread. This method will be implementing functionality provided by Java’s thread interrupt functionality.

Proposed code –

<cfscript> thread action="run" name="myThread" {
    while (!ThreadInterrupted()) {
         // execute task....
    }
}
</cfscript>

<cfscript> thread action="run" name="myThread" 
 {    
try { 
        // 1. if the interrupt flag is true, the thread is terminated 
        while (!ThreadInterrupted()) { 
            // execute tasks... 
        } 
    } catch (com.adobe.coldfusion.ThreadInterruptedException ie) {  
        // 2. When catch InterruptedException, thread is ready for gracefull termination 
    } 
} 
</cfscript>

Pros of the solution:

• Futureproofing with Java
• Thread Safety
• No data corruption or resource leaks

Cons of the solution:

• Customers will have to update their code if they had been using terminate method and attribute

While this was about a change that you can expect in CF2025, planning is also underway for the next release post CF2025. Some of the proposals around Java thread management the team has been thinking about are the below ones for the next release after 2025, are these –

• Virtual threads with JDK21 – Virtual threads represent lightweight, stackless threads that can be scheduled by the JVM’s scheduler. They are created and managed at the JVM level rather than relying on the underlying OS threads. Virtual threads offer a more efficient concurrency model compared to traditional OS threads, making it easier to write scalable and responsive applications. More on virtual threads can be found here: https://docs.oracle.com/en/java/javase/21/core/virtual-threads.html#GUID-2BCFC2DD-7D84-4B0C-9222-97F9C7C6C521
• Threadpool – Much older feature in Java but super useful and not present in ColdFusion yet. It entails providing capabilities to create and maintain a pool of pre-initialized threads ready to execute tasks as needed. The approach improves performance by reusing threads and minimizing the overhead of thread creation and destruction. Details about this –  https://docs.oracle.com/javase/tutorial/essential/concurrency/pools.html

Have any thoughts and opinions to share? Please comment or write to me on cdhoot@adobe.com with details about the following:

1. Whether you are using any of the methods (thread terminate & cfthread terminate) and what are you using it for? Some contexts around the application, code samples and notes around intended functionality will be extremely helpful in understanding your use case for these functions better, and thereby understanding the effectiveness of the proposed solution for it.
2. Your thoughts / ideas for the proposed solution for thread interrupt.
3. Your requirements around some thread management features under consideration for the release post CF2025, or any new feature you want us to consider for the same.

Signing off for now! Take care, do write to me. Your feedback is valuable!