# HG changeset patch
# User redestad
# Date 1522158105 -7200
#      Tue Mar 27 15:41:45 2018 +0200
# Node ID ff872a47461f9b6f61d471d212477923a193b9f8
# Parent  b39bc2eb8325eafc55b7c0d0f4dd5076b3d44561
8199717: Avoid calculating primordial thread stack bounds on VM startup
Reviewed-by: dholmes, rehn, stuefe

diff --git a/src/hotspot/os/linux/os_linux.cpp b/src/hotspot/os/linux/os_linux.cpp
--- a/src/hotspot/os/linux/os_linux.cpp
+++ b/src/hotspot/os/linux/os_linux.cpp
@@ -152,6 +152,13 @@
 
 static int clock_tics_per_sec = 100;
 
+// If the VM might have been created on the primordial thread, we need to resolve the
+// primordial thread stack bounds and check if the current thread might be the
+// primordial thread in places. If we know that the primordial thread is never used,
+// such as when the VM was created by one of the standard java launchers, we can
+// avoid this
+static bool suppress_primordial_thread_resolution = false;
+
 // For diagnostics to print a message once. see run_periodic_checks
 static sigset_t check_signal_done;
 static bool check_signals = true;
@@ -917,6 +924,9 @@
 
 // Check if current thread is the primordial thread, similar to Solaris thr_main.
 bool os::is_primordial_thread(void) {
+  if (suppress_primordial_thread_resolution) {
+    return false;
+  }
   char dummy;
   // If called before init complete, thread stack bottom will be null.
   // Can be called if fatal error occurs before initialization.
@@ -4936,7 +4946,11 @@
   if (Posix::set_minimum_stack_sizes() == JNI_ERR) {
     return JNI_ERR;
   }
-  Linux::capture_initial_stack(JavaThread::stack_size_at_create());
+
+  suppress_primordial_thread_resolution = Arguments::created_by_java_launcher();
+  if (!suppress_primordial_thread_resolution) {
+    Linux::capture_initial_stack(JavaThread::stack_size_at_create());
+  }
 
 #if defined(IA32)
   workaround_expand_exec_shield_cs_limit();