# Thread-parallel execution common blocks / DVODE **URL:** \ **Category:** Help\ **Created:** [August 4, 2025, 2:49pm UTC](https://fortran-lang.discourse.group/t/thread-parallel-execution-common-blocks-dvode/9984 "2025-08-04T14:49:15Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Jelle11](https://avatars.discourse-cdn.com/v4/letter/j/f9ae1b/32.png) [@Jelle11](https://fortran-lang.discourse.group/u/Jelle11)\ **Post date:** [August 4, 2025, 2:49pm UTC](https://fortran-lang.discourse.group/t/thread-parallel-execution-common-blocks-dvode/9984/1 "2025-08-04T14:49:15Z")
Hi all, I’m using DVODE to solve stiff differential equations within a finite element simulation in Abaqus. Ideally, the code should run in parallel across multiple CPUs for different cases. However, DVODE’s use of common blocks prevents this, as it isn’t thread-safe. Is there a straightforward way to make DVODE thread-safe? Alternatively, can anyone recommend a good Fortran-based solver for stiff ODEs that doesn’t rely on external libraries and supports parallel execution? Thanks in advance! ---
**Author:** ![jacobwilliams](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/jacobwilliams/32/10_2.png) [@jacobwilliams](https://fortran-lang.discourse.group/u/jacobwilliams)\ **Post date:** [August 4, 2025, 3:41pm UTC](https://fortran-lang.discourse.group/t/thread-parallel-execution-common-blocks-dvode/9984/2 "2025-08-04T15:41:46Z")
I started this a while back: > **[GitHub - jacobwilliams/dvode: Modern Fortran Edition of the DVODE ODE Solver](https://github.com/jacobwilliams/dvode)** > > Modern Fortran Edition of the DVODE ODE Solver I think I removed all the common blocks. But I don’t remember if this was finished or not. If you try it let me know if it works. ---
**Author:** ![CRquantum](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/crquantum/32/730_2.png) [@CRquantum](https://fortran-lang.discourse.group/u/CRquantum)\ **Post date:** [August 12, 2025, 8:19am UTC](https://fortran-lang.discourse.group/t/thread-parallel-execution-common-blocks-dvode/9984/3 "2025-08-12T08:19:32Z")
In 2013, G.D. Byrne Illinois Institute of Technology, Chicago, ILL S. Thompson, Radford University, Radford, VA released a F90 version of DVODE (and possibly some improvements are made) based on the original F77 DVODE. They put dvode solver in a module, and it no longer have the common block issue you mentioned. I used this this F90 DVODE inside a MPI program, it is fine. Initially this F90 dvode was on Thompson’s Radford University website. However, the link no longer work. Fortunately I have a backup of that website. As you can see from @jacobwilliams github link, at the bottom of his github webpage, you can find the backup website. > **[Files · main · Chen Rong / DVODE\_backup · GitLab](https://gitlab.com/CRquantum/dvode_backup/-/tree/main?ref_type=heads)** > > It is a backup of DVODE from https://www.radford.edu/~thompson/vodef90web/vodef90source/misc.html You can download the website, and open the index.html and you will see things like below: ![image](https://global.discourse-cdn.com/free1/uploads/fortran_lang/original/2X/b/b5a29cb0f9ec926841f5ce3663c183238c680dcc.png) In this webpage, if you click VODE\_F90 Source Code Demo Programs gives you access to that F90 dvode version, and there are examples teach you how to use the F90 DVODE. As mentioned, I used them in my MPI program (No OpenMP) and it works fine. if you click Kyle Niemeyer’s OpenMP compatible version of dvode\_f90\_m.f90 It gives a OpenMP compatible version of dvode. Of course, @jacobwilliams modernized DVODE may be even better. ————————————– PS. For your convenience, I upload the code of the F90 version and its examples, as well as the OpenMP compatible version here. [example1.f90](https://fortran-lang.discourse.group/uploads/short-url/sKumyKr3boEi9b24cUDVqzNHmB2.f90) (3.8 KB) [example2.f90](https://fortran-lang.discourse.group/uploads/short-url/8YtGVKwBBxjGlACY1hsvKMQPwqs.f90) (3.8 KB) [dvode\_f90\_m.f90](https://fortran-lang.discourse.group/uploads/short-url/fbkAJDz7FVFXbAN93AMxyhyzrMS.f90) (716.1 KB) [OpenMP\_dvode\_f90\_m.f90](https://fortran-lang.discourse.group/uploads/short-url/4mWiw2dZ6asmog4J3XR5T7o2Nsu.f90) (698.5 KB) ---
**Author:** ![Jelle11](https://avatars.discourse-cdn.com/v4/letter/j/f9ae1b/32.png) [@Jelle11](https://fortran-lang.discourse.group/u/Jelle11)\ **Post date:** [August 12, 2025, 8:41am UTC](https://fortran-lang.discourse.group/t/thread-parallel-execution-common-blocks-dvode/9984/4 "2025-08-12T08:41:00Z")
Thanks a lot to both of you for these answers! I will try to implement it in the near future. ---
**Author:** ![eelis](https://avatars.discourse-cdn.com/v4/letter/e/c6cbf5/32.png) [@eelis](https://fortran-lang.discourse.group/u/eelis)\ **Post date:** [August 12, 2025, 5:14pm UTC](https://fortran-lang.discourse.group/t/thread-parallel-execution-common-blocks-dvode/9984/5 "2025-08-12T17:14:00Z")
Can you give more details about this MPI program with DVODE? (can you share?) What did you do with it? And with MPI? I am interested in ZVODE with MPI, basically having large ODE system and distributing it. ---
**Author:** ![CRquantum](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/crquantum/32/730_2.png) [@CRquantum](https://fortran-lang.discourse.group/u/CRquantum)\ **Post date:** [August 12, 2025, 6:40pm UTC](https://fortran-lang.discourse.group/t/thread-parallel-execution-common-blocks-dvode/9984/6 "2025-08-12T18:40:32Z")
What the MPI code is doing is described in this paper, [https://ascpt.onlinelibrary.wiley.com/doi/full/10.1002/psp4.13113](https://ascpt.onlinelibrary.wiley.com/doi/full/10.1002/psp4.13113) But I don’t feel that I could share the code to be honest, and actually the code itself is not important here for the DVODE F90 version. However, I can describe what the code is doing and what the MPI is doing. It is mostly a Monte Carlo program. So you need a number of samples (say 1000 samples) to calculate the sample average. A sample can be a log-likelihood, which uses a quantity (a predicted value) that is obtained by solving a bunch of ODEs (say 3 ODEs). What the MPI does it, say we have 10 cores and 1000 samples, I let 1 core calculate 100 samples one by one. As mentioned, each sample requires solving say 3 ODEs. The ODEs solving is done by using the F90 version of DVODE solver. All I want to say is, in the MPI code I am doing, there is no need to make any changes to that F90 DVODE code. Because as you can see from my description, I am not trying to parallel the ODE solving process. Of course, if you have a large number of ODEs to solve, say 99999 ODEs, and you want a parallel ODE solver which can utilize all the CPU cores available to solve the 99999 ODEs, then you need a parallel ODE solver. Those DVODE or ZVODE solvers are not such native parallel ODE solvers as far as I know. To make them parallel (if possible), additional works need to be done. I don’t think the DOVDE solver we are discussing here is such a parallel ODE solver. Perhaps you could create a new topic about parallel ODE solvers, and see if people could give you some recommendations. Perhaps PVODE > **[ucrl-jc-132361.pdf](https://computing.llnl.gov/sites/default/files/ucrl-jc-132361.pdf)** > > 228.26 KB [https://journals.sagepub.com/doi/10.1177/109434209901300405](https://journals.sagepub.com/doi/10.1177/109434209901300405) is more relevant with you case? The paper says you may contact Alan Hindmarsh for PVODE code. ![image](https://global.discourse-cdn.com/free1/uploads/fortran_lang/original/2X/1/1ef17ac871d8c79b2646dfce29b34ee687976b86.png)