[Caffe2] Handle cpuinfo_initialize() failure (#114418)

malfet · web-flow · commit d62c7575338b · 2023-11-23T14:01:16.000-05:00
It can fail on ARM platform if `/sys` folder is not accessible. In that case, call `std::thread::hardware_concurrency()`, which is aligned with the thread_pool initialization logic of `c10::TaskThreadPoolBase:defaultNumThreads()` Further addresses issue raised in #113568 This is a cherry-pick of #114011 into release/2.1 branch (cherry picked from commit 310e306)
diff --git a/caffe2/utils/threadpool/ThreadPool.cc b/caffe2/utils/threadpool/ThreadPool.cc
@@ -41,8 +41,13 @@ namespace {
 }
 
 size_t getDefaultNumThreads() {
-  CAFFE_ENFORCE(cpuinfo_initialize(), "cpuinfo initialization failed");
-  int numThreads = cpuinfo_get_processors_count();
+  auto numThreads = 1U;
+  if (cpuinfo_initialize()) {
+    numThreads = std::max(cpuinfo_get_processors_count(), 1U);
+  } else {
+    LOG(WARNING) << "cpuinfo initialization failed";
+    numThreads = std::max(std::thread::hardware_concurrency(), 1U);
+  }
 
   bool applyCap = false;
 #if defined(C10_ANDROID)
@@ -109,7 +114,7 @@ size_t getDefaultNumThreads() {
    * detect if we are running under tsan, for now capping the default
    * threadcount to the tsan limit unconditionally.
    */
-  int tsanThreadLimit = 63;
+  auto tsanThreadLimit = 63U;
   numThreads = std::min(numThreads, tsanThreadLimit);
 
   return numThreads;
