Async threads in Lasso allow code to run asynchronously and in parallel to the currently processing page. They are useful for offloading tasks to improve response times and for recurring events like scheduled jobs. Async threads do not have access to web request data and their output is not available, so alternative methods like logging must be used. Context can be passed into async threads using variables. Debugging async threads requires techniques like testing code outside the async context, trapping for errors, and sending debug messages to external sources.

1. Advanced Track: Asynchronous Threads Bil Corry lasso.pro

2. What Are Async Threads? Code that executes in parallel to the currently processing page.

3. Why Use Async Threads? Off-load tasks Improve response time to enduser by off-loading tasks that do not need to provide immediate feedback to the enduser Recurring events Lasso Scheduled Events, Email Queue, etc all are async threads. Network-hooked services lp_site_restart sets up a TCP listener that receives commands to restart Lasso

4. Typical Lasso Request Model Browser sends HTTP request to the web server

5. Web server determines the request is for Lasso and passes it to the Lasso connector

6. Lasso connector communicates with Lasso Server and sends the request

7. Lasso Server parses request, replies to Lasso connector

8. Lasso connector replies to web server

9. Web server replies to browser

10. Lasso Async Thread Model Lasso page initiates new thread

11. Just like a normal page, the thread will run until: It terminates normally

12. It crashes

13. It is terminated for taking too long

14. Lasso site or server is shut down When configured as such, some threads never terminate

15. Lasso Async Thread Model (cont) Because the request comes from Lasso itself, async threads do NOT have access to the web request info, such as client_headers, action_params, etc.

16. It will also not have access to the variables of the page that created it.

17. All file paths must be absolute from the hard disk root – [include] does not work

18. Lasso Async Thread Model (cont) Output from the async thread is not available, so alternative methods must be used, such as logging to a file, a database, global variable or the Lasso console

19. An async thread will execute according to its priority and the load on Lasso

20. Basic Example Async threads are surrounded by curly-braces and initiated using ->asasyn c: [{'Hello World'}->asasync] The above code doesn't show anything in the browser, but it does run asynchronously.

21. Sending Data to Async Thread ->asasync allows you to add params to pass into the async thread [{ var('p1') = params->find('p1')->get(1)->value } ->asasync(-params=array('p1'=1, 'p2'=2))] Can also use globals (or other shared resources), but take care to correctly send the right message to the right thread and use [thread_atomic] to keep access to the global thread-safe

22. Template For Copying Vars To Async Thread <?LassoScript // from: http://www.lassotech.com/async // stuff on your page not async here... // -------------- BEGIN OF ASYNC CODE -------------- { // -------------- BEGIN OF ASYNC CODE -------------- // -------------------- // process async! // -------------------- // // NOTE: Code below this point is processed in it's own thread! // Lasso_ExecutionTimeLimit(60 * 60); // in seconds, set this to something reasonable Thread_SetPriority(Thread_GetCurrentID, Thread_Priority_Low); // set priority // recreate vars - this makes all the vars on the page available to the async thread iterate: params->(find:'-vars')->(get:1)->value, local:'var'; (var: #var->name) = #var->value; /iterate; // do stuff here that you want in it's own thread... // -------------- END OF ASYNC CODE -------------- }->(asasync: -params=(array: '-vars' = vars)); // -------------- END OF ASYNC CODE -------------- // do more stuff on the current page... ?>