Limit the number of task s in flight to 2x number of threads in the pool.

3 files changed, 12 insertions, 1 deletions

diff --git a/vespalib/src/vespa/vespalib/util/threadexecutor.h b/vespalib/src/vespa/vespalib/util/threadexecutor.h
index 3ec19ea9a71..c202a0a2373 100644
--- a/vespalib/src/vespa/vespalib/util/threadexecutor.h
+++ b/vespalib/src/vespa/vespalib/util/threadexecutor.h
@@ -15,6 +15,11 @@ class ThreadExecutor : public Executor,
                        public Syncable
 {
 public:
+    /**
+     * Get number of threads in the executor pool.
+     * @return number of threads in the pool
+     */
+    virtual size_t getNumThreads() const = 0;
 };
 
 } // namespace vespalib
diff --git a/vespalib/src/vespa/vespalib/util/threadstackexecutorbase.cpp b/vespalib/src/vespa/vespalib/util/threadstackexecutorbase.cpp
index 76557762479..21d1de2a29b 100644
--- a/vespalib/src/vespa/vespalib/util/threadstackexecutorbase.cpp
+++ b/vespalib/src/vespa/vespalib/util/threadstackexecutorbase.cpp
@@ -155,6 +155,10 @@ ThreadStackExecutorBase::start(uint32_t threads)
     }
 }
 
+size_t ThreadStackExecutorBase::getNumThreads() const {
+    return _pool->GetNumStartedThreads();
+}
+
 void
 ThreadStackExecutorBase::internalSetTaskLimit(uint32_t taskLimit)
 {
diff --git a/vespalib/src/vespa/vespalib/util/threadstackexecutorbase.h b/vespalib/src/vespa/vespalib/util/threadstackexecutorbase.h
index 4ea27a2bcde..ee142659027 100644
--- a/vespalib/src/vespa/vespalib/util/threadstackexecutorbase.h
+++ b/vespalib/src/vespa/vespalib/util/threadstackexecutorbase.h
@@ -98,7 +98,7 @@ private:
         void unblock();
     };
 
-    std::unique_ptr<FastOS_ThreadPool>  _pool;
+    std::unique_ptr<FastOS_ThreadPool>   _pool;
     Monitor                              _monitor;
     Stats                                _stats;
     Gate                                 _executorCompletion;
@@ -223,6 +223,8 @@ public:
      **/
     void wait_for_task_count(uint32_t task_count);
 
+    size_t getNumThreads() const override;
+
     /**
      * Shut down this executor. This will make this executor reject
      * all new tasks.