Revert "Revert "ART: Give JIT thread pool workers a peer""

This reverts commit 9dfb707.

Accept a live Java thread for the JIT, and adjust the tests
accordingly.

(cherry picked from commit 4471e4f)

Bug: 31684920
Test: m ART_TEST_JIT=true ART_TEST_INTERPRETER=true test-art-host
Change-Id: I92cbae1eaae05711b9069335cf1a5f7eb58b9fd8

Author: agampe

runtime/jit/jit.cc

@@ -145,7 +145,12 @@ Jit::Jit() : dump_info_on_shutdown_(false),
              memory_use_("Memory used for compilation", 16),
              lock_("JIT memory use lock"),
              use_jit_compilation_(true),
-             save_profiling_info_(false) {}
+             save_profiling_info_(false),
+             hot_method_threshold_(0),
+             warm_method_threshold_(0),
+             osr_method_threshold_(0),
+             priority_thread_weight_(0),
+             invoke_transition_weight_(0) {}
 
 Jit* Jit::Create(JitOptions* options, std::string* error_msg) {
   DCHECK(options->UseJitCompilation() || options->GetSaveProfilingInfo());
@@ -280,7 +285,11 @@ bool Jit::CompileMethod(ArtMethod* method, Thread* self, bool osr) {
 void Jit::CreateThreadPool() {
   // There is a DCHECK in the 'AddSamples' method to ensure the tread pool
   // is not null when we instrument.
-  thread_pool_.reset(new ThreadPool("Jit thread pool", 1));
+
+  // We need peers as we may report the JIT thread, e.g., in the debugger.
+  constexpr bool kJitPoolNeedsPeers = true;
+  thread_pool_.reset(new ThreadPool("Jit thread pool", 1, kJitPoolNeedsPeers));
+
   thread_pool_->SetPthreadPriority(kJitPoolThreadPthreadPriority);
   thread_pool_->StartWorkers(Thread::Current());
 }

runtime/runtime.cc

@@ -583,24 +583,6 @@ bool Runtime::Start() {
 
   started_ = true;
 
-  // Create the JIT either if we have to use JIT compilation or save profiling info.
-  // TODO(calin): We use the JIT class as a proxy for JIT compilation and for
-  // recoding profiles. Maybe we should consider changing the name to be more clear it's
-  // not only about compiling. b/28295073.
-  if (jit_options_->UseJitCompilation() || jit_options_->GetSaveProfilingInfo()) {
-    std::string error_msg;
-    if (!IsZygote()) {
-    // If we are the zygote then we need to wait until after forking to create the code cache
-    // due to SELinux restrictions on r/w/x memory regions.
-      CreateJit();
-    } else if (jit_options_->UseJitCompilation()) {
-      if (!jit::Jit::LoadCompilerLibrary(&error_msg)) {
-        // Try to load compiler pre zygote to reduce PSS. b/27744947
-        LOG(WARNING) << "Failed to load JIT compiler with error " << error_msg;
-      }
-    }
-  }
-
   if (!IsImageDex2OatEnabled() || !GetHeap()->HasBootImageSpace()) {
     ScopedObjectAccess soa(self);
     StackHandleScope<2> hs(soa.Self());
@@ -625,6 +607,27 @@ bool Runtime::Start() {
 
   Thread::FinishStartup();
 
+  // Create the JIT either if we have to use JIT compilation or save profiling info. This is
+  // done after FinishStartup as the JIT pool needs Java thread peers, which require the main
+  // ThreadGroup to exist.
+  //
+  // TODO(calin): We use the JIT class as a proxy for JIT compilation and for
+  // recoding profiles. Maybe we should consider changing the name to be more clear it's
+  // not only about compiling. b/28295073.
+  if (jit_options_->UseJitCompilation() || jit_options_->GetSaveProfilingInfo()) {
+    std::string error_msg;
+    if (!IsZygote()) {
+    // If we are the zygote then we need to wait until after forking to create the code cache
+    // due to SELinux restrictions on r/w/x memory regions.
+      CreateJit();
+    } else if (jit_options_->UseJitCompilation()) {
+      if (!jit::Jit::LoadCompilerLibrary(&error_msg)) {
+        // Try to load compiler pre zygote to reduce PSS. b/27744947
+        LOG(WARNING) << "Failed to load JIT compiler with error " << error_msg;
+      }
+    }
+  }
+
   system_class_loader_ = CreateSystemClassLoader(this);
 
   if (is_zygote_) {