From 1bcc689324bdee090eed035353724abc3fa7c909 Mon Sep 17 00:00:00 2001
From: Jan Niklas Hasse <jhasse@bixense.com>
Date: Tue, 26 Feb 2019 14:37:19 +0100
Subject: Take CPU set limitations into account when calculating processor
 count

Fixes #1278.
---
 src/util.cc | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/util.cc b/src/util.cc
index 47a5de2..ee810d6 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -485,6 +485,15 @@ int GetProcessorCount() {
   GetNativeSystemInfo(&info);
   return info.dwNumberOfProcessors;
 #else
+#ifdef CPU_COUNT
+  // The number of exposed processors might not represent the actual number of
+  // processors threads can run on. This happens when a CPU set limitation is
+  // active, see https://github.com/ninja-build/ninja/issues/1278
+  cpu_set_t set;
+  if (sched_getaffinity(getpid(), sizeof(set), &set) == 0) {
+    return CPU_COUNT(&set);
+  }
+#endif
   return sysconf(_SC_NPROCESSORS_ONLN);
 #endif
 }
-- 
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