For each randomly freeze

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Why does my parallel for each randomly freeze even though each branch has no ui interaction??
Thanks

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Hi @manish.pal ,

Try this approach

  • Use local variables inside each parallel branch
  • Avoid modifying the same collection inside parallel
  • Use ConcurrentDictionary or ConcurrentBag for thread-safe items
  • Or create a local copy for each iteration.
    cheers
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Parallel.ForEach can freeze even without UI interaction because the loop threads may block each other. This usually happens due to hidden async deadlocks, lock contention on shared resources, blocking I/O inside the loop, or exceptions that delay completion. Even if UI is not touched, any blocking call inside the loop can cause the thread pool to stall.

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@manish.pal

May I know what you are doing in parallel for each..are there any shared resources that you are using?

cheers

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Thanks for the inputs.
After debugging the braches invidually, i identified that the freeze was caused by a silent exception inside one of the parallel braches. since Countinue On Error was enabled, the exception didn’t surface, which caused a thread stall at the parallel schedular level. Disabling COE exposed the exception, and onnce that branch was corrected, the parallel forrach executed without blocking.

Thanks again for the help.

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