Merge branch 'devel' of github.com:arangodb/arangodb into devel

CHANGELOG

@@ -1,6 +1,10 @@
 devel
 -----
 
+* Fix strange shutdown hanger which came from the fact that currently
+  libgcc/libmusl wrongly detect multi-threadedness in statically linked
+  executables.
+
 * Enabled IPO with cmake as an option, default is on for release builds without
   google tests.
 

arangod/RestServer/arangod.cpp

@@ -332,10 +332,35 @@ namespace arangodb {
 // *restartAction = myRestartAction;
 // arangodb::application_features::ApplicationServer::server->beginShutdown();
 
+#ifdef __linux__
+
+// The following is a hack which is currently (September 2019) needed to
+// let our static executables compiled with libmusl and gcc 8.3.0 properly
+// detect that we are a multi-threaded application.
+// See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91737 for developments
+// in gcc/libgcc to address this issue.
+
+static void* g(void *p) {
+  return p;
+}
+
+static void gg() {
+}
+
+static void f() {
+  pthread_t t;
+  pthread_create(&t, nullptr, g, nullptr);
+  pthread_cancel(t);
+  pthread_join(t, nullptr);
+  static pthread_once_t once_control = PTHREAD_ONCE_INIT;
+  pthread_once(&once_control, gg);
+}
+#endif
+
 int main(int argc, char* argv[]) {
 #ifdef __linux__
-  // Do not delete this! See lib/Basics/operating-system.h for details.
+  // Do not delete this! See above for an explanation.
-  ThrowSomeException();
+  if (argc >= 1 && strcmp(argv[0], "not a/valid name") == 0) { f(); }
 #endif
 
   std::string workdir(arangodb::basics::FileUtils::currentDirectory().result());

lib/Basics/files.cpp

@@ -2659,20 +2659,3 @@ bool TRI_GETENV(char const* which, std::string& value) {
 #endif
 }
 
-//////////////////////////////////////////////////////////////////////////////
-/// @brief bug fix for some race on libmusl and static linking
-//////////////////////////////////////////////////////////////////////////////
-
-// The following function just throws an exception and catches it. This is
-// used on Linux for the case that we link statically and the underlying
-// C-library is libmusl. This configuration has a bug in libgcc which
-// triggers a shutdown busy loop (after main), provided the very first
-// exception being thrown in the life of the process happens in two threads
-// at the same time. By throwing right at the beginning of main() when the
-// process is still single-threaded, we circumvent this problem.
-#ifdef __linux__
-void ThrowSomeException() {
-  try { throw 42; } catch(int const&) {};
-}
-#endif
-

lib/Basics/operating-system.h

@@ -668,15 +668,6 @@
 #define TRI_uid_t uid_t
 #define TRI_gid_t gid_t
 
-// The following function just throws an exception and catches it. This is
-// used on Linux for the case that we link statically and the underlying
-// C-library is libmusl. This configuration has a bug in libgcc which
-// triggers a shutdown busy loop (after main), provided the very first
-// exception being thrown in the life of the process happens in two threads
-// at the same time. By throwing right at the beginning of main() when the
-// process is still single-threaded, we circumvent this problem.
-void ThrowSomeException();
-
 #endif
 
 // -----------------------------------------------------------------------------