[Lldb-commits] [lldb] 20048f3 - [lldb] use one shared ThreadPool and task groups

[Luboš Luňák via lldb-commits]

Author: Luboš Luňák
Date: 2022-05-04T06:18:20+02:00
New Revision: 20048f3150cf6c603c8f5a20912561048a868484

URL: https://github.com/llvm/llvm-project/commit/20048f3150cf6c603c8f5a20912561048a868484
DIFF: https://github.com/llvm/llvm-project/commit/20048f3150cf6c603c8f5a20912561048a868484.diff

LOG: [lldb] use one shared ThreadPool and task groups

As a preparation for parallelizing loading of symbols (D122975),
it is necessary to use just one thread pool to avoid using
a thread pool from inside a task of another thread pool.

Differential Revision: https://reviews.llvm.org/D123226

Added: 
    

Modified: 
    lldb/include/lldb/Core/Debugger.h
    lldb/source/Core/Debugger.cpp
    lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/include/lldb/Core/Debugger.h b/lldb/include/lldb/Core/Debugger.h
index 354230b7a88a3..8005e03071b24 100644
--- a/lldb/include/lldb/Core/Debugger.h
+++ b/lldb/include/lldb/Core/Debugger.h
@@ -49,6 +49,7 @@
 
 namespace llvm {
 class raw_ostream;
+class ThreadPool;
 }
 
 namespace lldb_private {
@@ -379,6 +380,9 @@ class Debugger : public std::enable_shared_from_this<Debugger>,
     return m_broadcaster_manager_sp;
   }
 
+  /// Shared thread poll. Use only with ThreadPoolTaskGroup.
+  static llvm::ThreadPool &GetThreadPool();
+
   /// Report warning events.
   ///
   /// Progress events will be delivered to any debuggers that have listeners

diff  --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
index a0785549e77ec..ff158dd1cfdfe 100644
--- a/lldb/source/Core/Debugger.cpp
+++ b/lldb/source/Core/Debugger.cpp
@@ -66,6 +66,7 @@
 #include "llvm/Support/DynamicLibrary.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Process.h"
+#include "llvm/Support/ThreadPool.h"
 #include "llvm/Support/Threading.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -1970,3 +1971,13 @@ Status Debugger::RunREPL(LanguageType language, const char *repl_options) {
 
   return err;
 }
+
+llvm::ThreadPool &Debugger::GetThreadPool() {
+  // NOTE: intentional leak to avoid issues with C++ destructor chain
+  static llvm::ThreadPool *g_thread_pool = nullptr;
+  static llvm::once_flag g_once_flag;
+  llvm::call_once(g_once_flag, []() {
+    g_thread_pool = new llvm::ThreadPool(llvm::optimal_concurrency());
+  });
+  return *g_thread_pool;
+}

diff  --git a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
index d0d5aead2c2b3..b743c84c10e01 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
@@ -13,6 +13,7 @@
 #include "Plugins/SymbolFile/DWARF/LogChannelDWARF.h"
 #include "Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h"
 #include "lldb/Core/DataFileCache.h"
+#include "lldb/Core/Debugger.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/Progress.h"
 #include "lldb/Symbol/ObjectFile.h"
@@ -94,7 +95,7 @@ void ManualDWARFIndex::Index() {
 
   // Share one thread pool across operations to avoid the overhead of
   // recreating the threads.
-  llvm::ThreadPool pool(llvm::optimal_concurrency(units_to_index.size()));
+  llvm::ThreadPoolTaskGroup task_group(Debugger::GetThreadPool());
 
   // Create a task runner that extracts dies for each DWARF unit in a
   // separate thread.
@@ -105,14 +106,14 @@ void ManualDWARFIndex::Index() {
   // to wait until all units have been indexed in case a DIE in one
   // unit refers to another and the indexes accesses those DIEs.
   for (size_t i = 0; i < units_to_index.size(); ++i)
-    pool.async(extract_fn, i);
-  pool.wait();
+    task_group.async(extract_fn, i);
+  task_group.wait();
 
   // Now create a task runner that can index each DWARF unit in a
   // separate thread so we can index quickly.
   for (size_t i = 0; i < units_to_index.size(); ++i)
-    pool.async(parser_fn, i);
-  pool.wait();
+    task_group.async(parser_fn, i);
+  task_group.wait();
 
   auto finalize_fn = [this, &sets, &progress](NameToDIE(IndexSet::*index)) {
     NameToDIE &result = m_set.*index;
@@ -122,15 +123,15 @@ void ManualDWARFIndex::Index() {
     progress.Increment();
   };
 
-  pool.async(finalize_fn, &IndexSet::function_basenames);
-  pool.async(finalize_fn, &IndexSet::function_fullnames);
-  pool.async(finalize_fn, &IndexSet::function_methods);
-  pool.async(finalize_fn, &IndexSet::function_selectors);
-  pool.async(finalize_fn, &IndexSet::objc_class_selectors);
-  pool.async(finalize_fn, &IndexSet::globals);
-  pool.async(finalize_fn, &IndexSet::types);
-  pool.async(finalize_fn, &IndexSet::namespaces);
-  pool.wait();
+  task_group.async(finalize_fn, &IndexSet::function_basenames);
+  task_group.async(finalize_fn, &IndexSet::function_fullnames);
+  task_group.async(finalize_fn, &IndexSet::function_methods);
+  task_group.async(finalize_fn, &IndexSet::function_selectors);
+  task_group.async(finalize_fn, &IndexSet::objc_class_selectors);
+  task_group.async(finalize_fn, &IndexSet::globals);
+  task_group.async(finalize_fn, &IndexSet::types);
+  task_group.async(finalize_fn, &IndexSet::namespaces);
+  task_group.wait();
 
   SaveToCache();
 }