From edc7689a7fa4caef1b97a6f0b940b98bf6d74f75 Mon Sep 17 00:00:00 2001
From: Jeffrey Walton <noloader@gmail.com>
Date: Sun, 20 May 2018 08:33:21 -0400
Subject: [PATCH] Fix overcommit resources for Scrypt parallelization (GH #641)

---
 scrypt.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/scrypt.cpp b/scrypt.cpp
index 5a53ca1e..3566c3e1 100644
--- a/scrypt.cpp
+++ b/scrypt.cpp
@@ -245,8 +245,14 @@ size_t Scrypt::DeriveKey(byte*derived, size_t derivedLen, const byte*secret, siz
     // 1: (B_0 ... B_{p-1}) <-- PBKDF2(P, S, 1, p * MFLen)
     PBKDF2_SHA256(B, B.size(), secret, secretLen, salt, saltLen, 1);
 
+    #ifdef _OPENMP
+    int threads = STDMIN(omp_get_max_threads(),
+        static_cast<int>(STDMIN(static_cast<size_t>(parallel),
+        static_cast<size_t>(std::numeric_limits<int>::max()))));
+    #endif
+
     // http://stackoverflow.com/q/49604260/608639
-    #pragma omp parallel
+    #pragma omp parallel num_threads(threads)
     {
         // Each thread gets its own copy
         AlignedSecByteBlock XY(static_cast<size_t>(blockSize * 256U));