# Optimistic Lock Exception

**URL:** https://forum.flowable.org/t/optimistic-lock-exception/10485
**Category:** Flowable Engine
**Created:** [May 8, 2023, 5:32pm UTC](https://forum.flowable.org/t/optimistic-lock-exception/10485 "2023-05-08T17:32:37Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![adityav](https://avatars.discourse-cdn.com/v4/letter/a/82dd89/32.png) [@adityav](https://forum.flowable.org/u/adityav)
#### Post date: [May 8, 2023, 5:32pm UTC](https://forum.flowable.org/t/optimistic-lock-exception/10485/1 "2023-05-08T17:32:37Z")

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Flow :  
Triggerable Task0(Async Triggerable Task) ----- Parallel Gateway ----\> Concurrent Future Delegate (Asyn Task 1) , Concurrent Future Delegate (Async Task2)

Task 0 - It is a triggerable task , Call Rest Apis(Spring Reactive) and then runtimeservice.trigger(execution, variables) is invoked once rest API invocation is completed.

Task 0 invokes parallel gateway which then invokes Task 1 and Task2 parallely .

Optimistic Lock Exception occurs when runtimeservice.trigger(execution, variables) in trigger method (Task0)