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Parfor hangs during execution

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Andrea Stevanato
Andrea Stevanato on 13 Jul 2018
Answered: DeepSea on 15 Aug 2021
How i can solve this problem that freeze parfor during execution?
Operation terminated by user during distcomp.remoteparfor/getCompleteIntervals (line 225)
In parallel_function>distributed_execution (line 823)
[tags, out] = P.getCompleteIntervals(chunkSize);
In parallel_function (line 590)
R = distributed_execution(...
Andrea Stevanato
Andrea Stevanato on 14 Jul 2018
I know what is deadlook but there aren't. My code works fine for first 10 iteration and after this hangs execution. Two days ago all works fine, yesterday no. Now I'm looking what are the situation for today.
Andrea Stevanato
Andrea Stevanato on 14 Jul 2018
I'm trying to install previous version of matlab, maybe 2017a/b. I am really disappointed of MATLAB's behavior

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Answers (6)

Muhammad Adil Raja
Muhammad Adil Raja on 27 Jan 2019
I am having this same issue for the last couple of days.

Gergely Papp
Gergely Papp on 2 Jul 2019
I have encountered the same issue, both with 2017/b and 2019/a. The calculations launch in the parallel workers, but along the way they hang 1-by-1. They would hang for days if I don't kill them manually.

Andrea Stevanato
Andrea Stevanato on 16 Jul 2018
It's possible to restart all workers without delete(gcp)?

Jayaram Theegala
Jayaram Theegala on 16 Jul 2018
Edited: Jayaram Theegala on 16 Jul 2018
Hello Andrea,
In order to understand the issue better, can you try reducing the number of iterations on your first loop, by setting "it" variable used in your first "for" loop to 1. Also, it may be helpful to just start your pool with 1 worker, and see if the issue still persists.
If the issue continues to happen even after the above changes, provide the following information:
1) Brief information about the function used within the parfor loop: Algorithms.TeMA.evolution
2) Does the issue happen without the above function?
3) Finally, it is generally advisable for outer-most loop to be parfor and the inner loops being for loops.

Zachary Eilon
Zachary Eilon on 26 Jun 2019
I am having a similar problem. A simple demo code is shown below, which enters an infinite loop within the parfor. This is on a 2-core MacBook Pro with 3.3 GHz Intel i7 processor. Running Matlab R2017b, but the same code seems to cause problems on a machine running R2019a.
k = 1e10;
for i = 1:k
parfor i = 1:k
lingyan yang
lingyan yang on 3 Jan 2021
is ther any updates I am encountering same issue with both matlab2019a and matlab 2020b. I am using particle swarm parallel setting, the optimization hangs in the middle of optimization, and won't continue untill i restart the system, very annoying
Nick on 25 May 2021
Same with me. Particle swarm function on Matlab 2020b in parallel macbook with 6 cores.

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DeepSea on 15 Aug 2021
I've been stucked in this problem for couples of weeks, and fixed it by removing "continue" in an if-judgement and a for-loop.
for CondA
if CondB
continue; % Avoid using "continue"


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