MCOL-5044 Adding EXTRA thread logic into FairThreadPool

primitives/primproc/bppsendthread.h

@@ -24,12 +24,13 @@
 
 #pragma once
 
+#include "fair_threadpool.h"
 #include "umsocketselector.h"
 #include <queue>
 #include <set>
 #include <condition_variable>
 #include "threadnaming.h"
-#include "prioritythreadpool.h"
+#include "fair_threadpool.h"
 
 namespace primitiveprocessor
 {
@@ -84,7 +85,7 @@ class BPPSendThread
   {
     return die;
   }
-  void setProcessorPool(boost::shared_ptr<threadpool::PriorityThreadPool> processorPool)
+  void setProcessorPool(boost::shared_ptr<threadpool::FairThreadPool> processorPool)
   {
     fProcessorPool = processorPool;
   }
@@ -146,9 +147,9 @@ class BPPSendThread
   /* secondary queue size restriction based on byte size */
   volatile uint64_t currentByteSize;
   uint64_t maxByteSize;
-  // Used to tell the PriorityThreadPool It should consider additional threads because a
+  // Used to tell the ThreadPool It should consider additional threads because a
   // queue full event has happened and a thread has been blocked.
-  boost::shared_ptr<threadpool::PriorityThreadPool> fProcessorPool;
+  boost::shared_ptr<threadpool::FairThreadPool> fProcessorPool;
 };
 
 }  // namespace primitiveprocessor

primitives/primproc/primitiveserver.cpp

@@ -1947,7 +1947,7 @@ struct ReadThread
   void operator()()
   {
     utils::setThreadName("PPReadThread");
-    threadpool::FairThreadPool* procPoolPtr = fPrimitiveServerPtr->getProcessorThreadPool();
+    boost::shared_ptr<threadpool::FairThreadPool> procPoolPtr = fPrimitiveServerPtr->getProcessorThreadPool();
     SBS bs;
     UmSocketSelector* pUmSocketSelector = UmSocketSelector::instance();
 
@@ -2322,8 +2322,8 @@ PrimitiveServer::PrimitiveServer(int serverThreads, int serverQueueSize, int pro
   fServerpool.setQueueSize(fServerQueueSize);
   fServerpool.setName("PrimitiveServer");
 
-  fProcessorPool = new threadpool::FairThreadPool(fProcessorWeight, highPriorityThreads,
+  fProcessorPool.reset(new threadpool::FairThreadPool(fProcessorWeight, highPriorityThreads,
-                                                      medPriorityThreads, lowPriorityThreads, 0);
+                                                      medPriorityThreads, lowPriorityThreads, 0));
 
   // We're not using either the priority or the job-clustering features, just need a threadpool
   // that can reschedule jobs, and an unlimited non-blocking queue

primitives/primproc/primitiveserver.h

@@ -36,7 +36,7 @@
 #include <boost/thread.hpp>
 
 #include "threadpool.h"
-#include "../../utils/threadpool/prioritythreadpool.h"
+#include "../../utils/threadpool/fair_threadpool.h"
 #include "fair_threadpool.h"
 #include "messagequeue.h"
 #include "blockrequestprocessor.h"

primitives/primproc/primitiveserverthreadpools.h

@@ -18,29 +18,29 @@
 #pragma once
 
 #include <boost/shared_ptr.hpp>
-#include "prioritythreadpool.h"
+#include "fair_threadpool.h"
 
 class PrimitiveServerThreadPools
 {
  public:
   PrimitiveServerThreadPools() = default;
-  PrimitiveServerThreadPools(boost::shared_ptr<threadpool::PriorityThreadPool> primServerThreadPool,
+  PrimitiveServerThreadPools(boost::shared_ptr<threadpool::FairThreadPool> primServerThreadPool,
-                             boost::shared_ptr<threadpool::PriorityThreadPool> OOBThreadPool)
+                             boost::shared_ptr<threadpool::FairThreadPool> OOBThreadPool)
    : fPrimServerThreadPool(primServerThreadPool), fOOBThreadPool(OOBThreadPool)
   {
   }
 
-  boost::shared_ptr<threadpool::PriorityThreadPool> getPrimitiveServerThreadPool()
+  boost::shared_ptr<threadpool::FairThreadPool> getPrimitiveServerThreadPool()
   {
     return fPrimServerThreadPool;
   }
 
-  boost::shared_ptr<threadpool::PriorityThreadPool> getOOBThreadPool()
+  boost::shared_ptr<threadpool::FairThreadPool> getOOBThreadPool()
   {
     return fOOBThreadPool;
   }
 
  private:
-  boost::shared_ptr<threadpool::PriorityThreadPool> fPrimServerThreadPool;
+  boost::shared_ptr<threadpool::FairThreadPool> fPrimServerThreadPool;
-  boost::shared_ptr<threadpool::PriorityThreadPool> fOOBThreadPool;
+  boost::shared_ptr<threadpool::FairThreadPool> fOOBThreadPool;
 };

primitives/primproc/primproc.h

@@ -35,7 +35,7 @@
 #include <map>
 
 #include "service.h"
-#include "prioritythreadpool.h"
+#include "fair_threadpool.h"
 #include "pp_logger.h"
 
 namespace primitiveprocessor
@@ -172,12 +172,12 @@ class ServicePrimProc : public Service, public Opt
     return startupRaceFlag_;
   }
 
-  boost::shared_ptr<threadpool::PriorityThreadPool> getPrimitiveServerThreadPool()
+  boost::shared_ptr<threadpool::FairThreadPool> getPrimitiveServerThreadPool()
   {
     return primServerThreadPool;
   }
 
-  boost::shared_ptr<threadpool::PriorityThreadPool> getOOBThreadPool()
+  boost::shared_ptr<threadpool::FairThreadPool> getOOBThreadPool()
   {
     return OOBThreadPool;
   }
@@ -190,6 +190,6 @@ class ServicePrimProc : public Service, public Opt
   static ServicePrimProc* fInstance;
   // Since C++20 flag's init value is false.
   std::atomic_flag startupRaceFlag_{false};
-  boost::shared_ptr<threadpool::PriorityThreadPool> primServerThreadPool;
+  boost::shared_ptr<threadpool::FairThreadPool> primServerThreadPool;
-  boost::shared_ptr<threadpool::PriorityThreadPool> OOBThreadPool;
+  boost::shared_ptr<threadpool::FairThreadPool> OOBThreadPool;
 };

utils/threadpool/fair_threadpool.cpp

@@ -35,7 +35,7 @@ namespace threadpool
 {
 FairThreadPool::FairThreadPool(uint targetWeightPerRun, uint highThreads, uint midThreads, uint lowThreads,
                                uint ID)
- : weightPerRun(targetWeightPerRun), id(ID)
+ : weightPerRun(targetWeightPerRun), id(ID), stopExtra_(false)
 {
   boost::thread* newThread;
   size_t numberOfThreads = highThreads + midThreads + lowThreads;
@@ -74,6 +74,20 @@ void FairThreadPool::addJob_(const Job& job, bool useLock)
 
   if (useLock)
     lk.lock();
+  // If some threads have blocked (because of output queue full)
+  // Temporarily add some extra worker threads to make up for the blocked threads.
+  if (blockedThreads_ > extraThreads_)
+  {
+    stopExtra_ = false;
+    newThread = threads.create_thread(ThreadHelper(this, PriorityThreadPool::Priority::EXTRA));
+    newThread->detach();
+    ++extraThreads_;
+  }
+  else if (blockedThreads_ == 0)
+  {
+    // Release the temporary threads -- some threads have become unblocked.
+    stopExtra_ = true;
+  }
 
   auto jobsListMapIter = txn2JobsListMap_.find(job.txnIdx_);
   if (jobsListMapIter == txn2JobsListMap_.end())  // there is no txn in the map
@@ -140,6 +154,13 @@ void FairThreadPool::threadFcn(const PriorityThreadPool::Priority preferredQueue
 
       if (weightedTxnsQueue_.empty())
       {
+        // If this is an EXTRA thread due toother threads blocking, and all blockers are unblocked,
+        // we don't want this one any more.
+        if (preferredQueue == PriorityThreadPool::Priority::EXTRA && stopExtra_)
+        {
+          --extraThreads_;
+          return;
+        }
         newJob.wait(lk);
         continue;  // just go on w/o re-taking the lock
       }

utils/threadpool/fair_threadpool.h

@@ -107,6 +107,23 @@ class FairThreadPool
   {
     return jobsRunning_.load(std::memory_order_relaxed);
   }
+  // If a job is blocked, we want to temporarily increase the number of threads managed by the pool
+  // A problem can occur if all threads are running long or blocked for a single query. Other
+  // queries won't get serviced, even though there are cpu cycles available.
+  // These calls are currently protected by respondLock in sendThread(). If you call from other
+  // places, you need to consider atomicity.
+  void incBlockedThreads()
+  {
+    ++blockedThreads_;
+  }
+  void decBlockedThreads()
+  {
+    --blockedThreads_;
+  }
+  uint32_t blockedThreadCount()
+  {
+    return blockedThreads_;
+  }
 
  protected:
  private:
@@ -160,6 +177,10 @@ class FairThreadPool
   std::atomic<size_t> jobsRunning_{0};
   std::atomic<size_t> threadCounts_{0};
   std::atomic<bool> stop_{false};
+
+  std::atomic<uint32_t> blockedThreads_{0};
+  std::atomic<uint32_t> extraThreads_{0};
+  bool stopExtra_;
 };
 
 }  // namespace threadpool