From 4559c8f3af087cfb58d4e37679aeaa5b630b94cf Mon Sep 17 00:00:00 2001
From: Tyson Whitehead <twhitehead@gmail.com>
Date: Sun, 29 Aug 2021 12:35:38 -0400
Subject: [PATCH] fixup! Note MPI fork depletion analysis issues in MPI
 installation guide

---
 docs/source/usersguide/install.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/docs/source/usersguide/install.rst b/docs/source/usersguide/install.rst
index 3090ae69e..d1aa6b6fa 100644
--- a/docs/source/usersguide/install.rst
+++ b/docs/source/usersguide/install.rst
@@ -387,6 +387,17 @@ i.e.
 
     CXX=mpicxx cmake /path/to/openmc
 
+If you are doing depletion analysis, you may have to set
+
+.. code-block:: python
+
+    openmc.deplete.pool.USE_MULTIPROCESSING = False
+
+in your python file before making any calls to the integrator depending on whether
+or not your MPI is compatible with forking (e.g., see the `OpenMPI FAQ entry about
+forking <https://www.open-mpi.org/faq/?category=tuning#fork-warning>`_). If it is
+not compatible, and this in not set, random hangs and crashes can result.
+
 Selecting HDF5 Installation
 +++++++++++++++++++++++++++