From a17bcfdced14f36acfec9eaf141120bd5413f7c0 Mon Sep 17 00:00:00 2001
From: Oscar Dowson <odow@users.noreply.github.com>
Date: Mon, 30 Oct 2023 09:10:02 +1300
Subject: [PATCH] Add note on thread-safety to README (#182)

---
 README.md | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/README.md b/README.md
index 90da3fe..03d2ea8 100644
--- a/README.md
+++ b/README.md
@@ -90,3 +90,20 @@ for a full list of the available options.
 
 The C API can be accessed via `HiGHS.Highs_xxx` functions, where the names and
 arguments are identical to the C API.
+
+## Threads
+
+HiGHS uses a global scheduler that is shared between threads.
+
+Before changing the number of theads using `MOI.Threads()`, you must call
+`Highs_resetGlobalScheduler(1)`:
+```julia
+using JuMP, HiGHS
+model = Model(HiGHS.Optimizer)
+Highs_resetGlobalScheduler(1)
+set_attribute(model, MOI.NumberOfThreads(), 1)
+```
+
+If modifying the number of HiGHS threads across different Julia threads, be sure
+to read the docstring of `Highs_resetGlobalScheduler`. In particular, resetting
+the scheduler is not thread-safe.