# While Loop in Binding does not stop the Script when removed **URL:** \ **Category:** Ignition\ **Tags:** perspective, scripting\ **Created:** [September 6, 2023, 4:48pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825 "2023-09-06T16:48:12Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Zachary\_Kacel1](https://avatars.discourse-cdn.com/v4/letter/z/ea666f/32.png) [@Zachary\_Kacel1](https://forum.inductiveautomation.com/u/Zachary_Kacel1)\ **Post date:** [September 6, 2023, 4:48pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/1 "2023-09-06T16:48:12Z")
While experimenting with While loops, I've concluded that I should avoid using them. However, during my usage of While loops, I believe I've identified a bug in Property Binding Scripts. If I unintentionally create an infinite while loop within a Property Binding and then remove it, the script continues to run even after the code is removed. Furthermore, if I create an infinite loop and then hit the apply button, I end up with two threads running even after removing the while loop and clicking apply. I've only allowed these threads to run for a few minutes, so I'm unsure if they will eventually terminate. Is this behavior normal for Property Binding Scripts, or is something unusual happening? I can duplicate this every time by just creating a new property binding and adding an infinite while loop then removing the loop from the script. ![while_loop](https://us1.discourse-cdn.com/inductiveautomation/original/3X/8/7/87b26c8638eb43ad1735aa0ef4a197dbc40cd52d.jpeg) ![while_loop_2](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/d/1d36b19c1ef447ccb8812068d5ecbc321e5718e8.jpeg) ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [September 6, 2023, 4:50pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/2 "2023-09-06T16:50:57Z")
Not a bug in Ignition. It is a bug in your code. An infinite loop (or a very long duration loop) within an event is pathological in an event-driven system. If you can't make your events run in a few milliseconds, then you should be using timers and state machines. (And, no, that doesn't mean using any form of `.sleep()`. The event routine must **exit**.) And no, they won't eventually end. They will burn CPU time until you restart the gateway. ---
**Author:** ![Zachary\_Kacel1](https://avatars.discourse-cdn.com/v4/letter/z/ea666f/32.png) [@Zachary\_Kacel1](https://forum.inductiveautomation.com/u/Zachary_Kacel1)\ **Post date:** [September 6, 2023, 4:54pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/3 "2023-09-06T16:54:53Z")
So even after I correct my mistake in the script I will still need to restart the gateway to free it back up? ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [September 6, 2023, 4:56pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/4 "2023-09-06T16:56:08Z")
Yes, editing an event script doesn't stop threads already running it. (This is true everywhere in Ignition.) ---
**Author:** ![Zachary\_Kacel1](https://avatars.discourse-cdn.com/v4/letter/z/ea666f/32.png) [@Zachary\_Kacel1](https://forum.inductiveautomation.com/u/Zachary_Kacel1)\ **Post date:** [September 6, 2023, 4:57pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/5 "2023-09-06T16:57:04Z")
Thanks ---
**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\ **Post date:** [September 6, 2023, 9:33pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/6 "2023-09-06T21:33:25Z")
> [@pturmel](#): > > And no, they won't eventually end. They will burn CPU time until you restart the gateway. I thought I had been able to kill someone else's infinite loop scripts using the gateway's Status | Diagnostics | Running Scripts | Cancel. This didn't require a gateway restart as far as I can remember. ---
**Author:** ![carlosbqz](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/carlosbqz/32/52324_2.png) [@carlosbqz](https://forum.inductiveautomation.com/u/carlosbqz)\ **Post date:** [September 6, 2023, 9:48pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/7 "2023-09-06T21:48:06Z")
> [@Transistor](#): > > I thought I had been able to kill someone else's infinite loop scripts using the gateway's Status | Diagnostics | Running Scripts | Cancel. I second this, I was able to stop an accidental infinite loop by cancelling it using the _Running Scripts_ tab (clarifying that I am not an expert on how Java works, so not totally sure if it's necessary to restart the gateway 😅). ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [September 6, 2023, 10:35pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/8 "2023-09-06T22:35:15Z")
I wouldn't do it on a production server. The JVM can become unstable, supposedly. Killing threads is a legacy java feature that comes with big warnings. ---
**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\ **Post date:** [September 6, 2023, 10:45pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/9 "2023-09-06T22:45:07Z")
The 'cancel' mechanism hooks into Jython to interrupt the next stack frame/call/etc performed. So, it's not using the same thread death mechanism Java explicitly warns you against... it also won't stop, in theory, a totally pointless busy loop, but as long as there's _some_ statement inside the loop (which there (always?) should be, it will stop just that executing thread. ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [September 6, 2023, 10:47pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/10 "2023-09-06T22:47:29Z")
> [@paul-griffith](#): > > but as long as there's _some_ statement inside the loop The example in this topic did not have any such statement. Just `pass`. (Must be I/O or synchronization/locking operations to be interruptible, IIRC.) ---
**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\ **Post date:** [September 6, 2023, 10:58pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/11 "2023-09-06T22:58:16Z")
Still works. We're adding a `TraceFunction` to the interpreter thread, and the `pass` is hit on `traceLine`, even though it's not actually a 'real' statement, so we're still able to stop there (by simply throwing an unexpected exception). [https://www.javadoc.io/static/org.python/jython-standalone/2.7.1/org/python/core/TraceFunction.html](https://www.javadoc.io/static/org.python/jython-standalone/2.7.1/org/python/core/TraceFunction.html) ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/b/2/b2c121f3382b63ec9a757d98520491f5c85fd5b6.png) ```auto com.inductiveautomation.ignition.common.script.ScriptManager$ScriptCanceledError: Script canceled: at com.inductiveautomation.ignition.common.script.ScriptManager$BreakTraceFunction.doBreak(ScriptManager.java:1043) at com.inductiveautomation.ignition.common.script.ScriptManager$BreakTraceFunction.traceException(ScriptManager.java:1066) at org.python.core.PyException.(PyException.java:55) at org.python.core.PyException.(PyException.java:43) at org.python.core.Py.JavaError(Py.java:547) at org.python.core.PyTableCode.call(PyTableCode.java:182) at org.python.core.PyBaseCode.call(PyBaseCode.java:306) at org.python.core.PyFunction.function ___call__ (PyFunction.java:474) at org.python.core.PyFunction. __call__ (PyFunction.java:469) at org.python.core.PyFunction. __call__ (PyFunction.java:464) at com.inductiveautomation.ignition.common.script.ScriptManager.runFunction(ScriptManager.java:846) at com.inductiveautomation.ignition.client.script.DesignerSystemUtilities.lambda$_invokeAsyncImpl$1(DesignerSystemUtilities.java:140) at java.base/java.lang.Thread.run(Thread.java:829) Ignition v(Dev Version) Java: Azul Systems, Inc. 11.0.17 ``` ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [September 6, 2023, 11:08pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/12 "2023-09-06T23:08:53Z")
> [@paul-griffith](#): > > We're adding a `TraceFunction` to the interpreter thread Sneaky. Wonder what the performance consequences are. ---
**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\ **Post date:** [September 6, 2023, 11:24pm UTC](https://forum.inductiveautomation.com/t/while-loop-in-binding-does-not-stop-the-script-when-removed/78825/13 "2023-09-06T23:24:02Z")
Jython lets you swap in a trace function 'live', so no implication until we try to interrupt.