Don't dlclose if blas_shutdown not found

Author: filikat

highs/util/HighsDynamicLibrary.cpp

@@ -11,6 +11,8 @@
 
 #include "util/HighsDynamicLibrary.h"
 
+#include "HConfig.h"
+
 #if defined(_WIN32) || defined(_WIN64)
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
@@ -65,23 +67,35 @@ bool HighsDynamicLibrary::load(const std::string& filename,
 void HighsDynamicLibrary::unload() {
   if (!handle_) return;
 
-#if defined(_WIN32) || defined(_WIN64)
-  FreeLibrary(static_cast<HMODULE>(handle_));
-#else
-  // check if blas_shutdown exists and potentially use it before dlclose-ing
+#ifdef HIPO_USES_OPENBLAS
+  // Openblas creates a thread pool that may still exist after dlclose-ing the
+  // library, leading to seg fault. blas_shutdown should prevent this, but its
+  // symbol is not always exposed. If the symbol exists, use it and then call
+  // dlclose. If the symbol does not exist, avoid calling dlclose.
 
   using shutdown_t = void (*)();
-
   shutdown_t shutdown_fn = nullptr;
-
   if (auto p = dlsym(handle_, "blas_shutdown"))
     shutdown_fn = reinterpret_cast<shutdown_t>(p);
   else if (auto p = dlsym(handle_, "openblas_shutdown"))
     shutdown_fn = reinterpret_cast<shutdown_t>(p);
 
-  if (shutdown_fn) shutdown_fn();
+  if (shutdown_fn) {
+    shutdown_fn();
+#if defined(_WIN32) || defined(_WIN64)
+    FreeLibrary(static_cast<HMODULE>(handle_));
+#else
+    dlclose(handle_);
+#endif
+  }
+
+#else
 
+#if defined(_WIN32) || defined(_WIN64)
+  FreeLibrary(static_cast<HMODULE>(handle_));
+#else
   dlclose(handle_);
+#endif
 #endif
 
   handle_ = nullptr;