From ccd9a414eb516e020fb74e042c90ed0128ffb890 Mon Sep 17 00:00:00 2001
From: Andrew Hutchings <andrew@linuxjedi.co.uk>
Date: Tue, 16 Oct 2018 17:55:41 +0100
Subject: [PATCH] MCOL-1810 Fix hang on low core count

Anything that links against joblist will spin up a threadpool upon
startup. This includes the tools setConfig/getConfig. It is possible on
a low core count machine or low CPU speed that the signal to the prune
thread to shutdown is sent before the thread has completed startup when
these quick-running tools are used.

This fix adds a mutex so that spin up and shutdown can't happen at the
same time as well as a stop watch in case we are shutting down when
either the thread is running or we haven't fully started.
---
 utils/threadpool/threadpool.cpp | 4 ++++
 utils/threadpool/threadpool.h   | 5 +++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/utils/threadpool/threadpool.cpp b/utils/threadpool/threadpool.cpp
index 0b1546e98..602f868c4 100644
--- a/utils/threadpool/threadpool.cpp
+++ b/utils/threadpool/threadpool.cpp
@@ -55,6 +55,7 @@ ThreadPool::~ThreadPool() throw()
 {
     try
     {
+        boost::mutex::scoped_lock initLock(fInitMutex);
         stop();
     }
     catch (...)
@@ -64,6 +65,7 @@ ThreadPool::~ThreadPool() throw()
 
 void ThreadPool::init()
 {
+    boost::mutex::scoped_lock initLock(fInitMutex);
     fThreadCount = 0;
     fGeneralErrors = 0;
     fFunctorErrors = 0;
@@ -89,6 +91,8 @@ void ThreadPool::pruneThread()
     while(true)
    {
         boost::system_time timeout = boost::get_system_time() + boost::posix_time::minutes(1);
+        if (fStop)
+            return;
         if (!fPruneThreadEnd.timed_wait(fPruneMutex, timeout))
         {
             while(!fPruneThreads.empty())
diff --git a/utils/threadpool/threadpool.h b/utils/threadpool/threadpool.h
index 1f0c6d0aa..4cb703c07 100644
--- a/utils/threadpool/threadpool.h
+++ b/utils/threadpool/threadpool.h
@@ -331,8 +331,9 @@ private:
 	uint32_t 	waitingFunctorsSize;
 	uint64_t fNextHandle;
 
-	std::string fName;  // Optional to add a name to the pool for debugging.
-	bool fDebug;
+    std::string fName;  // Optional to add a name to the pool for debugging.
+    bool fDebug;
+    boost::mutex fInitMutex;
     boost::mutex fPruneMutex;
     boost::condition fPruneThreadEnd;
     boost::thread* fPruneThread;